...

81 files changed, 1619 insertions, 7172 deletions

diff --git a/src/core/src/tonkadur/fate/v1/lang/computation/Access.java b/src/core/src/tonkadur/fate/v1/lang/computation/Access.java
deleted file mode 100644
index 843874c..0000000
--- a/src/core/src/tonkadur/fate/v1/lang/computation/Access.java
+++ /dev/null
@@ -1,139 +0,0 @@
-package tonkadur.fate.v1.lang.computation;
-
-import java.util.Collections;
-import java.util.List;
-
-import tonkadur.parser.Origin;
-
-import tonkadur.error.ErrorManager;
-
-import tonkadur.fate.v1.error.InvalidTypeException;
-
-import tonkadur.fate.v1.lang.meta.ComputationVisitor;
-import tonkadur.fate.v1.lang.meta.Computation;
-import tonkadur.fate.v1.lang.meta.Reference;
-
-import tonkadur.fate.v1.lang.type.CollectionType;
-import tonkadur.fate.v1.lang.type.Type;
-
-public class Access extends Computation
-{
-   /***************************************************************************/
-   /**** MEMBERS **************************************************************/
-   /***************************************************************************/
-   protected final Computation parent;
-   protected final Computation index;
-
-   /***************************************************************************/
-   /**** PROTECTED ************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   protected Access
-   (
-      final Origin origin,
-      final Computation parent,
-      final Type type,
-      final Computation index
-   )
-   {
-      super(origin, type);
-
-      this.parent = parent;
-      this.index = index;
-   }
-
-   /***************************************************************************/
-   /**** PUBLIC ***************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   public static Access build
-   (
-      final Origin origin,
-      Computation parent,
-      final Computation index
-   )
-   throws InvalidTypeException
-   {
-      Type current_type;
-
-      current_type = parent.get_type();
-
-      while (current_type.get_act_as_type().equals(Type.PTR))
-      {
-         parent = AtReference.build(origin, parent);
-         current_type = parent.get_type();
-      }
-
-      if (!index.get_type().can_be_used_as(Type.INT))
-      {
-         ErrorManager.handle
-         (
-            new InvalidTypeException
-            (
-               index.get_origin(),
-               current_type,
-               Collections.singleton(Type.INT),
-               index.toString()
-            )
-         );
-      }
-
-      if (!(current_type instanceof CollectionType))
-      {
-         ErrorManager.handle
-         (
-            new InvalidTypeException
-            (
-               origin,
-               current_type,
-               Collections.singleton(Type.LIST),
-               parent.toString()
-            )
-         );
-
-         current_type = Type.ANY;
-      }
-      else
-      {
-         current_type = ((CollectionType) current_type).get_content_type();
-      }
-
-      return new Access(origin, parent, current_type, index);
-   }
-
-
-   /**** Accessors ************************************************************/
-   @Override
-   public void get_visited_by (final ComputationVisitor cv)
-   throws Throwable
-   {
-      cv.visit_access(this);
-   }
-
-   public Computation get_index ()
-   {
-      return index;
-   }
-
-   public Computation get_parent ()
-   {
-      return parent;
-   }
-
-   /**** Misc. ****************************************************************/
-   @Override
-   public String toString ()
-   {
-      final StringBuilder sb = new StringBuilder();
-
-      sb.append("(Access (");
-      sb.append(type.get_name());
-      sb.append(") ");
-      sb.append(parent.toString());
-      sb.append(".");
-      sb.append(index.toString());
-      sb.append(")");
-
-      return sb.toString();
-   }
-}
diff --git a/src/core/src/tonkadur/fate/v1/lang/computation/AccessPointer.java b/src/core/src/tonkadur/fate/v1/lang/computation/AccessPointer.java
deleted file mode 100644
index fbc2ab7..0000000
--- a/src/core/src/tonkadur/fate/v1/lang/computation/AccessPointer.java
+++ /dev/null
@@ -1,144 +0,0 @@
-package tonkadur.fate.v1.lang.computation;
-
-import java.util.Collections;
-import java.util.List;
-
-import tonkadur.parser.Origin;
-
-import tonkadur.error.ErrorManager;
-
-import tonkadur.fate.v1.error.InvalidTypeException;
-
-import tonkadur.fate.v1.lang.meta.ComputationVisitor;
-import tonkadur.fate.v1.lang.meta.Computation;
-import tonkadur.fate.v1.lang.meta.Computation;
-
-import tonkadur.fate.v1.lang.type.CollectionType;
-import tonkadur.fate.v1.lang.type.PointerType;
-import tonkadur.fate.v1.lang.type.Type;
-
-public class AccessPointer extends Computation
-{
-   /***************************************************************************/
-   /**** MEMBERS **************************************************************/
-   /***************************************************************************/
-   protected final Computation parent;
-   protected final Computation index;
-
-   /***************************************************************************/
-   /**** PROTECTED ************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   protected AccessPointer
-   (
-      final Origin origin,
-      final Computation parent,
-      final Type type,
-      final Computation index
-   )
-   {
-      super
-      (
-         origin,
-         new PointerType(origin, type, "(ptr " + type.toString() + ") autogen")
-      );
-
-      this.parent = parent;
-      this.index = index;
-   }
-
-   /***************************************************************************/
-   /**** PUBLIC ***************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   public static AccessPointer build
-   (
-      final Origin origin,
-      Computation parent,
-      final Computation index
-   )
-   throws InvalidTypeException
-   {
-      Type current_type;
-
-      current_type = parent.get_type();
-
-      while (current_type.get_act_as_type().equals(Type.PTR))
-      {
-         parent = AtComputation.build(origin, parent);
-         current_type = parent.get_type();
-      }
-
-      if (!index.get_type().can_be_used_as(Type.INT))
-      {
-         ErrorManager.handle
-         (
-            new InvalidTypeException
-            (
-               index.get_origin(),
-               current_type,
-               Collections.singleton(Type.INT),
-               index.toString()
-            )
-         );
-      }
-
-      if (!(current_type instanceof CollectionType))
-      {
-         ErrorManager.handle
-         (
-            new InvalidTypeException
-            (
-               origin,
-               current_type,
-               Collections.singleton(Type.LIST),
-               parent.toString()
-            )
-         );
-
-         current_type = Type.ANY;
-      }
-      else
-      {
-         current_type = ((CollectionType) current_type).get_content_type();
-      }
-
-      return new AccessPointer(origin, parent, current_type, index);
-   }
-
-
-   /**** Accessors ************************************************************/
-   @Override
-   public void get_visited_by (final ComputationVisitor cv)
-   throws Throwable
-   {
-      cv.visit_access_pointer(this);
-   }
-
-   public Computation get_index ()
-   {
-      return index;
-   }
-
-   public Computation get_parent ()
-   {
-      return parent;
-   }
-
-   /**** Misc. ****************************************************************/
-   @Override
-   public String toString ()
-   {
-      final StringBuilder sb = new StringBuilder();
-
-      sb.append("(AccessPointer (");
-      sb.append(type.get_name());
-      sb.append(") ");
-      sb.append(parent.get_name());
-      sb.append(".");
-      sb.append(index.toString());
-      sb.append(")");
-
-      return sb.toString();
-   }
-}
diff --git a/src/core/src/tonkadur/fate/v1/lang/computation/AddElementAtComputation.java b/src/core/src/tonkadur/fate/v1/lang/computation/AddElementAtComputation.java
deleted file mode 100644
index 2b0c06a..0000000
--- a/src/core/src/tonkadur/fate/v1/lang/computation/AddElementAtComputation.java
+++ /dev/null
@@ -1,113 +0,0 @@
-package tonkadur.fate.v1.lang.computation;
-
-import tonkadur.parser.Origin;
-import tonkadur.parser.ParsingError;
-
-import tonkadur.fate.v1.lang.type.Type;
-
-import tonkadur.fate.v1.lang.meta.ComputationVisitor;
-import tonkadur.fate.v1.lang.meta.Computation;
-import tonkadur.fate.v1.lang.meta.RecurrentChecks;
-
-public class AddElementAtComputation extends Computation
-{
-   /***************************************************************************/
-   /**** MEMBERS **************************************************************/
-   /***************************************************************************/
-   protected final Computation index;
-   protected final Computation element;
-   protected final Computation collection;
-
-   /***************************************************************************/
-   /**** PROTECTED ************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   protected AddElementAtComputation
-   (
-      final Origin origin,
-      final Computation index,
-      final Computation element,
-      final Computation collection
-   )
-   {
-      super(origin, collection.get_type());
-
-      this.index = index;
-      this.collection = collection;
-      this.element = element;
-   }
-
-   /***************************************************************************/
-   /**** PUBLIC ***************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   public static AddElementAtComputation build
-   (
-      final Origin origin,
-      final Computation index,
-      final Computation element,
-      final Computation collection
-   )
-   throws ParsingError
-   {
-      RecurrentChecks.assert_is_a_list_of(collection, element);
-      RecurrentChecks.assert_can_be_used_as(index, Type.INT);
-
-      return new AddElementAtComputation(origin, index, element, collection);
-   }
-
-   /**** Accessors ************************************************************/
-   @Override
-   public void get_visited_by (final ComputationVisitor cv)
-   throws Throwable
-   {
-      cv.visit_add_element_at(this);
-   }
-
-   public Computation get_collection ()
-   {
-      return collection;
-   }
-
-   public Computation get_index ()
-   {
-      return index;
-   }
-
-   public Computation get_element ()
-   {
-      return element;
-   }
-
-
-   /**** Misc. ****************************************************************/
-   @Override
-   public String toString ()
-   {
-      final StringBuilder sb = new StringBuilder();
-
-      sb.append("(AddElementAt");
-      sb.append(System.lineSeparator());
-      sb.append(System.lineSeparator());
-
-      sb.append("index:");
-      sb.append(System.lineSeparator());
-      sb.append(index.toString());
-      sb.append(System.lineSeparator());
-      sb.append(System.lineSeparator());
-
-      sb.append("element:");
-      sb.append(System.lineSeparator());
-      sb.append(element.toString());
-      sb.append(System.lineSeparator());
-      sb.append(System.lineSeparator());
-
-      sb.append("collection:");
-      sb.append(System.lineSeparator());
-      sb.append(collection.toString());
-
-      sb.append(")");
-
-      return sb.toString();
-   }
-}
diff --git a/src/core/src/tonkadur/fate/v1/lang/computation/AddElementComputation.java b/src/core/src/tonkadur/fate/v1/lang/computation/AddElementComputation.java
deleted file mode 100644
index b99d94c..0000000
--- a/src/core/src/tonkadur/fate/v1/lang/computation/AddElementComputation.java
+++ /dev/null
@@ -1,94 +0,0 @@
-package tonkadur.fate.v1.lang.computation;
-
-import tonkadur.parser.Origin;
-import tonkadur.parser.ParsingError;
-
-import tonkadur.fate.v1.lang.meta.ComputationVisitor;
-import tonkadur.fate.v1.lang.meta.Computation;
-import tonkadur.fate.v1.lang.meta.RecurrentChecks;
-
-public class AddElementComputation extends Computation
-{
-   /***************************************************************************/
-   /**** MEMBERS **************************************************************/
-   /***************************************************************************/
-   protected final Computation element;
-   protected final Computation collection;
-
-   /***************************************************************************/
-   /**** PROTECTED ************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   protected AddElementComputation
-   (
-      final Origin origin,
-      final Computation element,
-      final Computation collection
-   )
-   {
-      super(origin, collection.get_type());
-
-      this.collection = collection;
-      this.element = element;
-   }
-
-   /***************************************************************************/
-   /**** PUBLIC ***************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   public static AddElementComputation build
-   (
-      final Origin origin,
-      final Computation element,
-      final Computation collection
-   )
-   throws ParsingError
-   {
-      RecurrentChecks.assert_is_a_collection_of(collection, element);
-
-      return new AddElementComputation(origin, element, collection);
-   }
-
-   /**** Accessors ************************************************************/
-   @Override
-   public void get_visited_by (final ComputationVisitor cv)
-   throws Throwable
-   {
-      cv.visit_add_element(this);
-   }
-
-   public Computation get_collection ()
-   {
-      return collection;
-   }
-
-   public Computation get_element ()
-   {
-      return element;
-   }
-
-   /**** Misc. ****************************************************************/
-   @Override
-   public String toString ()
-   {
-      final StringBuilder sb = new StringBuilder();
-
-      sb.append("(AddElement");
-      sb.append(System.lineSeparator());
-      sb.append(System.lineSeparator());
-
-      sb.append("element:");
-      sb.append(System.lineSeparator());
-      sb.append(element.toString());
-      sb.append(System.lineSeparator());
-      sb.append(System.lineSeparator());
-
-      sb.append("collection:");
-      sb.append(System.lineSeparator());
-      sb.append(collection.toString());
-
-      sb.append(")");
-
-      return sb.toString();
-   }
-}
diff --git a/src/core/src/tonkadur/fate/v1/lang/computation/AddElementsOfComputation.java b/src/core/src/tonkadur/fate/v1/lang/computation/AddElementsOfComputation.java
deleted file mode 100644
index 1538fcb..0000000
--- a/src/core/src/tonkadur/fate/v1/lang/computation/AddElementsOfComputation.java
+++ /dev/null
@@ -1,104 +0,0 @@
-package tonkadur.fate.v1.lang.computation;
-
-import tonkadur.parser.Origin;
-import tonkadur.parser.ParsingError;
-
-import tonkadur.fate.v1.lang.type.CollectionType;
-
-import tonkadur.fate.v1.lang.meta.ComputationVisitor;
-import tonkadur.fate.v1.lang.meta.Computation;
-import tonkadur.fate.v1.lang.meta.RecurrentChecks;
-
-public class AddElementsOfComputation extends Computation
-{
-   /***************************************************************************/
-   /**** MEMBERS **************************************************************/
-   /***************************************************************************/
-   protected final Computation other_collection;
-   protected final Computation collection;
-
-   /***************************************************************************/
-   /**** PROTECTED ************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   protected AddElementsOfComputation
-   (
-      final Origin origin,
-      final Computation other_collection,
-      final Computation collection
-   )
-   {
-      super(origin, collection.get_type());
-
-      this.collection = collection;
-      this.other_collection = other_collection;
-   }
-
-   /***************************************************************************/
-   /**** PUBLIC ***************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   public static AddElementsOfComputation build
-   (
-      final Origin origin,
-      final Computation other_collection,
-      final Computation collection
-   )
-   throws ParsingError
-   {
-      RecurrentChecks.assert_is_a_collection(collection);
-      RecurrentChecks.assert_is_a_collection(other_collection);
-      RecurrentChecks.assert_can_be_used_as
-      (
-         other_collection.get_origin(),
-         ((CollectionType) other_collection.get_type()).get_content_type(),
-         ((CollectionType) collection.get_type()).get_content_type()
-      );
-
-      return new AddElementsOfComputation(origin, other_collection, collection);
-   }
-
-   /**** Accessors ************************************************************/
-   @Override
-   public void get_visited_by (final ComputationVisitor cv)
-   throws Throwable
-   {
-      cv.visit_add_elements_of(this);
-   }
-
-   public Computation get_source_collection ()
-   {
-      return other_collection;
-   }
-
-   public Computation get_target_collection ()
-   {
-      return collection;
-   }
-
-   /**** Misc. ****************************************************************/
-   @Override
-   public String toString ()
-   {
-      final StringBuilder sb = new StringBuilder();
-
-      sb.append("(AddElementsOf");
-      sb.append(System.lineSeparator());
-      sb.append(System.lineSeparator());
-
-      sb.append("other_collection:");
-      sb.append(System.lineSeparator());
-      sb.append(other_collection.toString());
-      sb.append(System.lineSeparator());
-      sb.append(System.lineSeparator());
-
-      sb.append("collection:");
-      sb.append(System.lineSeparator());
-      sb.append(collection.toString());
-
-      sb.append(")");
-
-      return sb.toString();
-   }
-
-}
diff --git a/src/core/src/tonkadur/fate/v1/lang/computation/AddressOperator.java b/src/core/src/tonkadur/fate/v1/lang/computation/AddressOperator.java
deleted file mode 100644
index a4482b3..0000000
--- a/src/core/src/tonkadur/fate/v1/lang/computation/AddressOperator.java
+++ /dev/null
@@ -1,60 +0,0 @@
-package tonkadur.fate.v1.lang.computation;
-
-import tonkadur.parser.Origin;
-
-import tonkadur.fate.v1.lang.type.PointerType;
-
-import tonkadur.fate.v1.lang.meta.ComputationVisitor;
-import tonkadur.fate.v1.lang.meta.Reference;
-import tonkadur.fate.v1.lang.meta.Computation;
-
-public class AddressOperator extends Computation
-{
-   /***************************************************************************/
-   /**** MEMBERS **************************************************************/
-   /***************************************************************************/
-   protected final Reference referred;
-
-   /***************************************************************************/
-   /**** PROTECTED ************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   public AddressOperator (final Origin origin, final Reference referred)
-   {
-      super
-      (
-         origin,
-         new PointerType(origin, referred.get_type(), "auto generated")
-      );
-      this.referred = referred;
-   }
-
-   /***************************************************************************/
-   /**** PUBLIC ***************************************************************/
-   /***************************************************************************/
-   /**** Accessors ************************************************************/
-   @Override
-   public void get_visited_by (final ComputationVisitor cv)
-   throws Throwable
-   {
-      cv.visit_address_operator(this);
-   }
-
-   public Reference get_target ()
-   {
-      return referred;
-   }
-
-   /**** Misc. ****************************************************************/
-   @Override
-   public String toString ()
-   {
-      final StringBuilder sb = new StringBuilder();
-
-      sb.append("(AddressOf ");
-      sb.append(referred.get_name());
-      sb.append(") ");
-
-      return sb.toString();
-   }
-}
diff --git a/src/core/src/tonkadur/fate/v1/lang/computation/CarCdr.java b/src/core/src/tonkadur/fate/v1/lang/computation/CarCdr.java
deleted file mode 100644
index 58e099d..0000000
--- a/src/core/src/tonkadur/fate/v1/lang/computation/CarCdr.java
+++ /dev/null
@@ -1,125 +0,0 @@
-package tonkadur.fate.v1.lang.computation;
-
-import java.util.Collections;
-
-import tonkadur.parser.Origin;
-
-import tonkadur.error.ErrorManager;
-
-import tonkadur.fate.v1.error.InvalidTypeException;
-
-import tonkadur.fate.v1.lang.meta.ComputationVisitor;
-import tonkadur.fate.v1.lang.meta.Computation;
-
-import tonkadur.fate.v1.lang.type.ConsType;
-import tonkadur.fate.v1.lang.type.Type;
-
-public class CarCdr extends Computation
-{
-   /***************************************************************************/
-   /**** MEMBERS **************************************************************/
-   /***************************************************************************/
-   protected final Computation parent;
-   protected final boolean is_car;
-
-   /***************************************************************************/
-   /**** PROTECTED ************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   protected CarCdr
-   (
-      final Origin origin,
-      final Computation parent,
-      final boolean is_car,
-      final Type type
-   )
-   {
-      super(origin, type);
-
-      this.parent = parent;
-      this.is_car = is_car;
-   }
-
-   /***************************************************************************/
-   /**** PUBLIC ***************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   public static CarCdr build
-   (
-      final Origin origin,
-      final Computation parent,
-      final boolean is_car
-   )
-   throws InvalidTypeException
-   {
-      Type current_type;
-
-      current_type = parent.get_type();
-
-      if (!(current_type instanceof ConsType))
-      {
-         ErrorManager.handle
-         (
-            new InvalidTypeException
-            (
-               origin,
-               current_type,
-               Collections.singletonList(Type.CONS)
-            )
-         );
-
-         current_type = Type.ANY;
-      }
-      else if (is_car)
-      {
-         current_type = ((ConsType) current_type).get_car_type();
-      }
-      else
-      {
-         current_type = ((ConsType) current_type).get_cdr_type();
-      }
-
-      return new CarCdr(origin, parent, is_car, current_type);
-   }
-
-   /**** Accessors ************************************************************/
-   @Override
-   public void get_visited_by (final ComputationVisitor cv)
-   throws Throwable
-   {
-      cv.visit_car_cdr(this);
-   }
-
-   public Computation get_parent ()
-   {
-      return parent;
-   }
-
-   public boolean is_car ()
-   {
-      return is_car;
-   }
-
-   /**** Misc. ****************************************************************/
-   @Override
-   public String toString ()
-   {
-      final StringBuilder sb = new StringBuilder();
-
-      if (is_car)
-      {
-         sb.append("(car (");
-      }
-      else
-      {
-         sb.append("(cdr (");
-      }
-
-      sb.append(type.get_name());
-      sb.append(") ");
-      sb.append(parent);
-      sb.append(")");
-
-      return sb.toString();
-   }
-}
diff --git a/src/core/src/tonkadur/fate/v1/lang/computation/ConsComputation.java b/src/core/src/tonkadur/fate/v1/lang/computation/ConsComputation.java
deleted file mode 100644
index 04d58ff..0000000
--- a/src/core/src/tonkadur/fate/v1/lang/computation/ConsComputation.java
+++ /dev/null
@@ -1,74 +0,0 @@
-package tonkadur.fate.v1.lang.computation;
-
-import tonkadur.parser.Origin;
-
-import tonkadur.fate.v1.lang.type.ConsType;
-
-import tonkadur.fate.v1.lang.meta.ComputationVisitor;
-import tonkadur.fate.v1.lang.meta.Computation;
-
-public class ConsComputation extends Computation
-{
-   /***************************************************************************/
-   /**** MEMBERS **************************************************************/
-   /***************************************************************************/
-   protected final Computation car;
-   protected final Computation cdr;
-
-   /***************************************************************************/
-   /**** PROTECTED ************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   public ConsComputation
-   (
-      final Origin origin,
-      final Computation car,
-      final Computation cdr
-   )
-   {
-      super
-      (
-         origin,
-         new ConsType(origin, car.get_type(), cdr.get_type(), "auto generated")
-      );
-
-      this.car = car;
-      this.cdr = cdr;
-   }
-
-   /***************************************************************************/
-   /**** PUBLIC ***************************************************************/
-   /***************************************************************************/
-   /**** Accessors ************************************************************/
-   @Override
-   public void get_visited_by (final ComputationVisitor cv)
-   throws Throwable
-   {
-      cv.visit_cons(this);
-   }
-
-   public Computation get_car ()
-   {
-      return car;
-   }
-
-   public Computation get_cdr ()
-   {
-      return cdr;
-   }
-
-   /**** Misc. ****************************************************************/
-   @Override
-   public String toString ()
-   {
-      final StringBuilder sb = new StringBuilder();
-
-      sb.append("(Cons ");
-      sb.append(car.toString());
-      sb.append(" ");
-      sb.append(car.toString());
-      sb.append(") ");
-
-      return sb.toString();
-   }
-}
diff --git a/src/core/src/tonkadur/fate/v1/lang/computation/CountOperator.java b/src/core/src/tonkadur/fate/v1/lang/computation/CountOperator.java
deleted file mode 100644
index a46387d..0000000
--- a/src/core/src/tonkadur/fate/v1/lang/computation/CountOperator.java
+++ /dev/null
@@ -1,98 +0,0 @@
-package tonkadur.fate.v1.lang.computation;
-
-import tonkadur.error.ErrorManager;
-
-import tonkadur.parser.Origin;
-import tonkadur.parser.ParsingError;
-
-import tonkadur.fate.v1.lang.type.Type;
-
-import tonkadur.fate.v1.lang.meta.ComputationVisitor;
-import tonkadur.fate.v1.lang.meta.Computation;
-import tonkadur.fate.v1.lang.meta.RecurrentChecks;
-
-public class CountOperator extends Computation
-{
-   /***************************************************************************/
-   /**** MEMBERS **************************************************************/
-   /***************************************************************************/
-   protected final Computation element;
-   protected final Computation collection;
-
-   /***************************************************************************/
-   /**** PROTECTED ************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   protected CountOperator
-   (
-      final Origin origin,
-      final Computation element,
-      final Computation collection
-   )
-   {
-      super(origin, Type.INT);
-
-      this.collection = collection;
-      this.element = element;
-   }
-
-   /***************************************************************************/
-   /**** PUBLIC ***************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   public static CountOperator build
-   (
-      final Origin origin,
-      final Computation element,
-      final Computation collection
-   )
-   throws ParsingError
-   {
-      RecurrentChecks.assert_is_a_collection_of(collection, element);
-
-      return new CountOperator(origin, element, collection);
-   }
-
-   /**** Accessors ************************************************************/
-   public Computation get_collection ()
-   {
-      return collection;
-   }
-
-   public Computation get_element ()
-   {
-      return element;
-   }
-
-   @Override
-   public void get_visited_by (final ComputationVisitor cv)
-   throws Throwable
-   {
-      cv.visit_count_operator(this);
-   }
-
-   /**** Misc. ****************************************************************/
-   @Override
-   public String toString ()
-   {
-      final StringBuilder sb = new StringBuilder();
-
-      sb.append("(CountOperator");
-      sb.append(System.lineSeparator());
-      sb.append(System.lineSeparator());
-
-      sb.append("element:");
-      sb.append(System.lineSeparator());
-      sb.append(element.toString());
-      sb.append(System.lineSeparator());
-      sb.append(System.lineSeparator());
-
-      sb.append("collection:");
-      sb.append(System.lineSeparator());
-      sb.append(collection.toString());
-
-      sb.append(")");
-
-      return sb.toString();
-   }
-}
diff --git a/src/core/src/tonkadur/fate/v1/lang/computation/ExtraComputationInstance.java b/src/core/src/tonkadur/fate/v1/lang/computation/ExtraComputationInstance.java
index 5f5b572..7cb5178 100644
--- a/src/core/src/tonkadur/fate/v1/lang/computation/ExtraComputationInstance.java
+++ b/src/core/src/tonkadur/fate/v1/lang/computation/ExtraComputationInstance.java
@@ -11,7 +11,7 @@ import tonkadur.fate.v1.lang.meta.ComputationVisitor;
 import tonkadur.fate.v1.lang.meta.ExtraComputation;
 import tonkadur.fate.v1.lang.meta.RecurrentChecks;
 
-public class ExtraComputationInstance extends Computation
+public class ExtraComputationInstance extends GenericComputation
 {
    protected final ExtraComputation computation;
    protected final List<Computation> parameters;
@@ -27,7 +27,7 @@ public class ExtraComputationInstance extends Computation
       final List<Computation> parameters
    )
    {
-      super(origin, computation.get_returned_type());
+      super(origin, computation.get_returned_type(), computation.get_name());
 
       this.computation = computation;
       this.parameters = parameters;
diff --git a/src/core/src/tonkadur/fate/v1/lang/computation/FieldAccess.java b/src/core/src/tonkadur/fate/v1/lang/computation/FieldAccess.java
index 56708ff..3949aca 100644
--- a/src/core/src/tonkadur/fate/v1/lang/computation/FieldAccess.java
+++ b/src/core/src/tonkadur/fate/v1/lang/computation/FieldAccess.java
@@ -11,12 +11,13 @@ import tonkadur.fate.v1.error.InvalidTypeException;
 import tonkadur.fate.v1.error.UnknownStructureFieldException;
 
 import tonkadur.fate.v1.lang.meta.ComputationVisitor;
-import tonkadur.fate.v1.lang.meta.Reference;
 import tonkadur.fate.v1.lang.meta.Computation;
 
 import tonkadur.fate.v1.lang.type.StructType;
 import tonkadur.fate.v1.lang.type.Type;
 
+import tonkadur.fate.v1.lang.computation.generic.AtReference;
+
 public class FieldAccess extends Computation
 {
    /***************************************************************************/
@@ -53,9 +54,7 @@ public class FieldAccess extends Computation
       Computation parent,
       final String field
    )
-   throws
-      InvalidTypeException,
-      UnknownStructureFieldException
+   throws Throwable
    {
       Type current_type;
 
@@ -63,7 +62,14 @@ public class FieldAccess extends Computation
 
       while (current_type.get_act_as_type().equals(Type.PTR))
       {
-         parent = AtReference.build(origin, (Reference) parent);
+         parent =
+            GenericComputation.build
+            (
+               origin,
+               "at",
+               Collections.singletonList(parent)
+            );
+
          current_type = parent.get_type();
       }
 
@@ -96,9 +102,7 @@ public class FieldAccess extends Computation
       Computation parent,
       final List<String> field_sequence
    )
-   throws
-      InvalidTypeException,
-      UnknownStructureFieldException
+   throws Throwable
    {
       for (final String field: field_sequence)
       {
diff --git a/src/core/src/tonkadur/fate/v1/lang/computation/FilterComputation.java b/src/core/src/tonkadur/fate/v1/lang/computation/FilterComputation.java
deleted file mode 100644
index 821c231..0000000
--- a/src/core/src/tonkadur/fate/v1/lang/computation/FilterComputation.java
+++ /dev/null
@@ -1,136 +0,0 @@
-package tonkadur.fate.v1.lang.computation;
-
-import java.util.Collections;
-import java.util.List;
-import java.util.ArrayList;
-
-import tonkadur.parser.Origin;
-import tonkadur.parser.ParsingError;
-
-import tonkadur.fate.v1.lang.type.Type;
-import tonkadur.fate.v1.lang.type.CollectionType;
-
-import tonkadur.fate.v1.lang.meta.ComputationVisitor;
-import tonkadur.fate.v1.lang.meta.Computation;
-import tonkadur.fate.v1.lang.meta.Computation;
-import tonkadur.fate.v1.lang.meta.RecurrentChecks;
-
-public class FilterComputation extends Computation
-{
-   /***************************************************************************/
-   /**** MEMBERS **************************************************************/
-   /***************************************************************************/
-   protected final List<Computation> extra_params;
-   protected final Computation lambda_function;
-   protected final Computation collection;
-
-   /***************************************************************************/
-   /**** PROTECTED ************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   protected FilterComputation
-   (
-      final Origin origin,
-      final Computation lambda_function,
-      final Computation collection,
-      final List<Computation> extra_params
-   )
-   {
-      super(origin, collection.get_type());
-
-      this.lambda_function = lambda_function;
-      this.collection = collection;
-      this.extra_params = extra_params;
-   }
-
-   /***************************************************************************/
-   /**** PUBLIC ***************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   public static FilterComputation build
-   (
-      final Origin origin,
-      final Computation lambda_function,
-      final Computation collection,
-      final List<Computation> extra_params
-   )
-   throws ParsingError
-   {
-      final List<Type> target_signature;
-
-      target_signature = new ArrayList<Type>();
-
-      RecurrentChecks.assert_is_a_collection(collection);
-
-      target_signature.add
-      (
-         ((CollectionType) collection.get_type()).get_content_type()
-      );
-
-      for (final Computation c: extra_params)
-      {
-         target_signature.add(c.get_type());
-      }
-
-      RecurrentChecks.assert_lambda_matches_types
-      (
-         lambda_function,
-         Type.BOOL,
-         target_signature
-      );
-
-      return
-         new FilterComputation
-         (
-            origin,
-            lambda_function,
-            collection,
-            extra_params
-         );
-   }
-
-   /**** Accessors ************************************************************/
-   @Override
-   public void get_visited_by (final ComputationVisitor cv)
-   throws Throwable
-   {
-      cv.visit_filter(this);
-   }
-
-   public Computation get_lambda_function ()
-   {
-      return lambda_function;
-   }
-
-   public Computation get_collection ()
-   {
-      return collection;
-   }
-
-   public List<Computation> get_extra_parameters ()
-   {
-      return extra_params;
-   }
-
-   /**** Misc. ****************************************************************/
-   @Override
-   public String toString ()
-   {
-      final StringBuilder sb = new StringBuilder();
-
-      sb.append("(Filter ");
-      sb.append(lambda_function.toString());
-      sb.append(" ");
-      sb.append(collection.toString());
-
-      for (final Computation c: extra_params)
-      {
-         sb.append(" ");
-         sb.append(c.toString());
-      }
-
-      sb.append(")");
-
-      return sb.toString();
-   }
-}
diff --git a/src/core/src/tonkadur/fate/v1/lang/computation/Fold.java b/src/core/src/tonkadur/fate/v1/lang/computation/Fold.java
deleted file mode 100644
index 1e9041b..0000000
--- a/src/core/src/tonkadur/fate/v1/lang/computation/Fold.java
+++ /dev/null
@@ -1,170 +0,0 @@
-package tonkadur.fate.v1.lang.computation;
-
-import java.util.ArrayList;
-import java.util.List;
-
-import tonkadur.parser.Origin;
-import tonkadur.parser.ParsingError;
-
-import tonkadur.fate.v1.lang.type.Type;
-import tonkadur.fate.v1.lang.type.LambdaType;
-import tonkadur.fate.v1.lang.type.CollectionType;
-
-import tonkadur.fate.v1.lang.meta.ComputationVisitor;
-import tonkadur.fate.v1.lang.meta.Computation;
-import tonkadur.fate.v1.lang.meta.Computation;
-import tonkadur.fate.v1.lang.meta.RecurrentChecks;
-
-public class Fold extends Computation
-{
-   /***************************************************************************/
-   /**** MEMBERS **************************************************************/
-   /***************************************************************************/
-   protected final List<Computation> extra_params;
-   protected final Computation lambda_function;
-   protected final Computation initial_value;
-   protected final Computation collection;
-   protected final boolean is_foldl;
-
-   /***************************************************************************/
-   /**** PROTECTED ************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   protected Fold
-   (
-      final Origin origin,
-      final Computation lambda_function,
-      final Computation initial_value,
-      final Computation collection,
-      final boolean is_foldl,
-      final List<Computation> extra_params,
-      final Type act_as
-   )
-   {
-      super(origin, act_as);
-
-      this.lambda_function = lambda_function;
-      this.initial_value = initial_value;
-      this.collection = collection;
-      this.is_foldl = is_foldl;
-      this.extra_params = extra_params;
-   }
-
-   /***************************************************************************/
-   /**** PUBLIC ***************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   public static Fold build
-   (
-      final Origin origin,
-      final Computation lambda_function,
-      final Computation initial_value,
-      final Computation collection,
-      final boolean is_foldl,
-      final List<Computation> extra_params
-   )
-   throws ParsingError
-   {
-      final List<Type> types_in;
-
-      types_in = new ArrayList<Type>();
-
-      RecurrentChecks.assert_is_a_collection(collection);
-
-      types_in.add(initial_value.get_type());
-      types_in.add
-      (
-         ((CollectionType) collection.get_type()).get_content_type()
-      );
-
-      for (final Computation c: extra_params)
-      {
-         types_in.add(c.get_type());
-      }
-
-      RecurrentChecks.assert_lambda_matches_types
-      (
-         lambda_function,
-         initial_value.get_type(),
-         types_in
-      );
-
-      return
-         new Fold
-         (
-            origin,
-            lambda_function,
-            initial_value,
-            collection,
-            is_foldl,
-            extra_params,
-            initial_value.get_type()
-         );
-   }
-
-   /**** Accessors ************************************************************/
-   @Override
-   public void get_visited_by (final ComputationVisitor cv)
-   throws Throwable
-   {
-      cv.visit_fold(this);
-   }
-
-   public Computation get_lambda_function ()
-   {
-      return lambda_function;
-   }
-
-   public Computation get_initial_value ()
-   {
-      return initial_value;
-   }
-
-   public Computation get_collection ()
-   {
-      return collection;
-   }
-
-   public boolean is_foldl ()
-   {
-      return is_foldl;
-   }
-
-   public List<Computation> get_extra_parameters ()
-   {
-      return extra_params;
-   }
-
-   /**** Misc. ****************************************************************/
-   @Override
-   public String toString ()
-   {
-      final StringBuilder sb = new StringBuilder();
-
-      if (is_foldl)
-      {
-         sb.append("(Foldl ");
-      }
-      else
-      {
-         sb.append("(Foldr ");
-      }
-
-      sb.append(lambda_function.toString());
-
-      sb.append(" ");
-      sb.append(initial_value.toString());
-      sb.append(" ");
-      sb.append(collection.toString());
-
-      for (final Computation c: extra_params)
-      {
-         sb.append(" ");
-         sb.append(c.toString());
-      }
-
-      sb.append(")");
-
-      return sb.toString();
-   }
-}
diff --git a/src/core/src/tonkadur/fate/v1/lang/computation/GenericComputation.java b/src/core/src/tonkadur/fate/v1/lang/computation/GenericComputation.java
new file mode 100644
index 0000000..84b5739
--- /dev/null
+++ b/src/core/src/tonkadur/fate/v1/lang/computation/GenericComputation.java
@@ -0,0 +1,162 @@
+package tonkadur.fate.v1.lang.computation;
+
+import java.util.Collection;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+import tonkadur.parser.Origin;
+
+import tonkadur.functional.Cons;
+
+import tonkadur.fate.v1.lang.type.Type;
+
+import tonkadur.fate.v1.lang.meta.ComputationVisitor;
+import tonkadur.fate.v1.lang.meta.Computation;
+
+public class GenericComputation extends Computation
+{
+   /***************************************************************************/
+   /**** STATIC ***************************************************************/
+   /***************************************************************************/
+   protected static final Map<String, Cons<GenericComputation, Object>>
+      REGISTERED;
+
+   static
+   {
+      REGISTERED = new HashMap<String, Cons<GenericComputation, Object>>();
+   }
+
+   public static GenericComputation build
+   (
+      final Origin origin,
+      final String name,
+      final List<Computation> call_parameters
+   )
+   throws Throwable
+   {
+      final Cons<GenericComputation, Object> target;
+
+      target = REGISTERED.get(name);
+
+      if (target == null)
+      {
+         // TODO Exception handling.
+      }
+
+      return target.get_car().build(origin, call_parameters, target.get_cdr());
+   }
+
+   /***************************************************************************/
+   /**** MEMBERS **************************************************************/
+   /***************************************************************************/
+   protected final String name;
+
+   /***************************************************************************/
+   /**** PROTECTED ************************************************************/
+   /***************************************************************************/
+   /**** Constructors *********************************************************/
+   protected GenericComputation
+   (
+      final Origin origin,
+      final Type type,
+      final String name
+   )
+   {
+      super(origin, type);
+
+      this.name = name;
+   }
+
+   protected GenericComputation build
+   (
+      final Origin origin,
+      final List<Computation> call_parameters,
+      final Object constructor_parameter
+   )
+   throws Throwable
+   {
+      throw
+         new Exception
+         (
+            "Missing build function for GenericComputation '"
+            + name
+            + "'."
+         );
+   }
+
+   protected void register
+   (
+      final String name,
+      final Object constructor_parameter
+   )
+   throws Exception
+   {
+      if (REGISTERED.containsKey(name))
+      {
+         // TODO Exception handling.
+         new Exception
+         (
+            "There already is a GenericComputation with the name '"
+            + name
+            + "'."
+         );
+
+         return;
+      }
+
+      REGISTERED.put(name, new Cons(this, constructor_parameter));
+   }
+
+   protected void register (final Object constructor_parameter)
+   throws Exception
+   {
+      register(get_name(), constructor_parameter);
+   }
+
+   protected void register
+   (
+      final Collection<String> names,
+      final Object constructor_parameter
+   )
+   throws Exception
+   {
+      for (final String name: names)
+      {
+         register(name, constructor_parameter);
+      }
+   }
+
+   /***************************************************************************/
+   /**** PUBLIC ***************************************************************/
+   /***************************************************************************/
+   /**** Constructors *********************************************************/
+
+   /**** Accessors ************************************************************/
+   @Override
+   public void get_visited_by (final ComputationVisitor cv)
+   throws Throwable
+   {
+      cv.visit_generic_computation(this);
+   }
+
+   public String get_name ()
+   {
+      return name;
+   }
+
+   /**** Misc. ****************************************************************/
+   @Override
+   public String toString ()
+   {
+      final StringBuilder sb = new StringBuilder();
+
+      sb.append("(GenericInstruction (");
+      sb.append(type.get_name());
+      sb.append(") ");
+      sb.append(get_name());
+      sb.append(")");
+
+      return sb.toString();
+   }
+}
diff --git a/src/core/src/tonkadur/fate/v1/lang/computation/IndexOfOperator.java b/src/core/src/tonkadur/fate/v1/lang/computation/IndexOfOperator.java
deleted file mode 100644
index 3269dbb..0000000
--- a/src/core/src/tonkadur/fate/v1/lang/computation/IndexOfOperator.java
+++ /dev/null
@@ -1,96 +0,0 @@
-package tonkadur.fate.v1.lang.computation;
-
-import tonkadur.parser.Origin;
-import tonkadur.parser.ParsingError;
-
-import tonkadur.fate.v1.lang.type.Type;
-
-import tonkadur.fate.v1.lang.meta.ComputationVisitor;
-import tonkadur.fate.v1.lang.meta.Computation;
-import tonkadur.fate.v1.lang.meta.RecurrentChecks;
-
-public class IndexOfOperator extends Computation
-{
-   /***************************************************************************/
-   /**** MEMBERS **************************************************************/
-   /***************************************************************************/
-   protected final Computation element;
-   protected final Computation collection;
-
-   /***************************************************************************/
-   /**** PROTECTED ************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   protected IndexOfOperator
-   (
-      final Origin origin,
-      final Computation element,
-      final Computation collection
-   )
-   {
-      super(origin, Type.INT);
-
-      this.collection = collection;
-      this.element = element;
-   }
-
-   /***************************************************************************/
-   /**** PUBLIC ***************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   public static IndexOfOperator build
-   (
-      final Origin origin,
-      final Computation element,
-      final Computation collection
-   )
-   throws ParsingError
-   {
-      RecurrentChecks.assert_is_a_collection_of(collection, element);
-
-      return new IndexOfOperator(origin, element, collection);
-   }
-
-   /**** Accessors ************************************************************/
-   @Override
-   public void get_visited_by (final ComputationVisitor cv)
-   throws Throwable
-   {
-      cv.visit_index_of_operator(this);
-   }
-
-   public Computation get_collection ()
-   {
-      return collection;
-   }
-
-   public Computation get_element ()
-   {
-      return element;
-   }
-
-   /**** Misc. ****************************************************************/
-   @Override
-   public String toString ()
-   {
-      final StringBuilder sb = new StringBuilder();
-
-      sb.append("(IndexOfOperator");
-      sb.append(System.lineSeparator());
-      sb.append(System.lineSeparator());
-
-      sb.append("element:");
-      sb.append(System.lineSeparator());
-      sb.append(element.toString());
-      sb.append(System.lineSeparator());
-      sb.append(System.lineSeparator());
-
-      sb.append("collection:");
-      sb.append(System.lineSeparator());
-      sb.append(collection.toString());
-
-      sb.append(")");
-
-      return sb.toString();
-   }
-}
diff --git a/src/core/src/tonkadur/fate/v1/lang/computation/IndexedFilterComputation.java b/src/core/src/tonkadur/fate/v1/lang/computation/IndexedFilterComputation.java
deleted file mode 100644
index 573a78f..0000000
--- a/src/core/src/tonkadur/fate/v1/lang/computation/IndexedFilterComputation.java
+++ /dev/null
@@ -1,137 +0,0 @@
-package tonkadur.fate.v1.lang.computation;
-
-import java.util.Collections;
-import java.util.List;
-import java.util.ArrayList;
-
-import tonkadur.parser.Origin;
-import tonkadur.parser.ParsingError;
-
-import tonkadur.fate.v1.lang.type.Type;
-import tonkadur.fate.v1.lang.type.CollectionType;
-
-import tonkadur.fate.v1.lang.meta.ComputationVisitor;
-import tonkadur.fate.v1.lang.meta.Computation;
-import tonkadur.fate.v1.lang.meta.Computation;
-import tonkadur.fate.v1.lang.meta.RecurrentChecks;
-
-public class IndexedFilterComputation extends Computation
-{
-   /***************************************************************************/
-   /**** MEMBERS **************************************************************/
-   /***************************************************************************/
-   protected final List<Computation> extra_params;
-   protected final Computation lambda_function;
-   protected final Computation collection;
-
-   /***************************************************************************/
-   /**** PROTECTED ************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   protected IndexedFilterComputation
-   (
-      final Origin origin,
-      final Computation lambda_function,
-      final Computation collection,
-      final List<Computation> extra_params
-   )
-   {
-      super(origin, collection.get_type());
-
-      this.lambda_function = lambda_function;
-      this.collection = collection;
-      this.extra_params = extra_params;
-   }
-
-   /***************************************************************************/
-   /**** PUBLIC ***************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   public static IndexedFilterComputation build
-   (
-      final Origin origin,
-      final Computation lambda_function,
-      final Computation collection,
-      final List<Computation> extra_params
-   )
-   throws ParsingError
-   {
-      final List<Type> target_signature;
-
-      target_signature = new ArrayList<Type>();
-
-      RecurrentChecks.assert_is_a_collection(collection);
-
-      target_signature.add(Type.INT);
-      target_signature.add
-      (
-         ((CollectionType) collection.get_type()).get_content_type()
-      );
-
-      for (final Computation c: extra_params)
-      {
-         target_signature.add(c.get_type());
-      }
-
-      RecurrentChecks.assert_lambda_matches_types
-      (
-         lambda_function,
-         Type.BOOL,
-         target_signature
-      );
-
-      return
-         new IndexedFilterComputation
-         (
-            origin,
-            lambda_function,
-            collection,
-            extra_params
-         );
-   }
-
-   /**** Accessors ************************************************************/
-   @Override
-   public void get_visited_by (final ComputationVisitor cv)
-   throws Throwable
-   {
-      cv.visit_indexed_filter(this);
-   }
-
-   public Computation get_lambda_function ()
-   {
-      return lambda_function;
-   }
-
-   public Computation get_collection ()
-   {
-      return collection;
-   }
-
-   public List<Computation> get_extra_parameters ()
-   {
-      return extra_params;
-   }
-
-   /**** Misc. ****************************************************************/
-   @Override
-   public String toString ()
-   {
-      final StringBuilder sb = new StringBuilder();
-
-      sb.append("(IndexedFilter ");
-      sb.append(lambda_function.toString());
-      sb.append(" ");
-      sb.append(collection.toString());
-
-      for (final Computation c: extra_params)
-      {
-         sb.append(" ");
-         sb.append(c.toString());
-      }
-
-      sb.append(")");
-
-      return sb.toString();
-   }
-}
diff --git a/src/core/src/tonkadur/fate/v1/lang/computation/IndexedMapComputation.java b/src/core/src/tonkadur/fate/v1/lang/computation/IndexedMapComputation.java
deleted file mode 100644
index f85616a..0000000
--- a/src/core/src/tonkadur/fate/v1/lang/computation/IndexedMapComputation.java
+++ /dev/null
@@ -1,140 +0,0 @@
-package tonkadur.fate.v1.lang.computation;
-
-import java.util.List;
-import java.util.ArrayList;
-
-import tonkadur.parser.Origin;
-import tonkadur.parser.ParsingError;
-
-import tonkadur.fate.v1.lang.type.Type;
-import tonkadur.fate.v1.lang.type.LambdaType;
-import tonkadur.fate.v1.lang.type.CollectionType;
-
-import tonkadur.fate.v1.lang.meta.ComputationVisitor;
-import tonkadur.fate.v1.lang.meta.Computation;
-import tonkadur.fate.v1.lang.meta.Computation;
-import tonkadur.fate.v1.lang.meta.RecurrentChecks;
-
-public class IndexedMapComputation extends Computation
-{
-   /***************************************************************************/
-   /**** MEMBERS **************************************************************/
-   /***************************************************************************/
-   protected final List<Computation> extra_params;
-   protected final Computation lambda_function;
-   protected final Computation collection;
-
-   /***************************************************************************/
-   /**** PROTECTED ************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   protected IndexedMapComputation
-   (
-      final Origin origin,
-      final Computation lambda_function,
-      final Computation collection,
-      final List<Computation> extra_params,
-      final Type output_type
-   )
-   {
-      super(origin, output_type);
-
-      this.lambda_function = lambda_function;
-      this.collection = collection;
-      this.extra_params = extra_params;
-   }
-
-   /***************************************************************************/
-   /**** PUBLIC ***************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   public static IndexedMapComputation build
-   (
-      final Origin origin,
-      final Computation lambda_function,
-      final Computation collection,
-      final List<Computation> extra_params
-   )
-   throws Throwable
-   {
-      final List<Type> in_types;
-
-      in_types = new ArrayList<Type>();
-
-      RecurrentChecks.assert_is_a_collection(collection);
-
-      in_types.add(Type.INT);
-      in_types.add
-      (
-         ((CollectionType) collection.get_type()).get_content_type()
-      );
-
-      for (final Computation c: extra_params)
-      {
-         in_types.add(c.get_type());
-      }
-
-      RecurrentChecks.assert_lambda_matches_types(lambda_function, in_types);
-
-      return
-         new IndexedMapComputation
-         (
-            origin,
-            lambda_function,
-            collection,
-            extra_params,
-            CollectionType.build
-            (
-               origin,
-               ((LambdaType) lambda_function.get_type()).get_return_type(),
-               ((CollectionType) collection.get_type()).is_set(),
-               "auto generated"
-            )
-         );
-   }
-
-   /**** Accessors ************************************************************/
-   @Override
-   public void get_visited_by (final ComputationVisitor cv)
-   throws Throwable
-   {
-      cv.visit_indexed_map(this);
-   }
-
-   public Computation get_lambda_function ()
-   {
-      return lambda_function;
-   }
-
-   public Computation get_collection ()
-   {
-      return collection;
-   }
-
-   public List<Computation> get_extra_parameters ()
-   {
-      return extra_params;
-   }
-
-   /**** Misc. ****************************************************************/
-   @Override
-   public String toString ()
-   {
-      final StringBuilder sb = new StringBuilder();
-
-      sb.append("(IndexedMap ");
-      sb.append(lambda_function.toString());
-      sb.append(" ");
-      sb.append(collection.toString());
-
-      for (final Computation c: extra_params)
-      {
-         sb.append(" ");
-         sb.append(c.toString());
-      }
-
-      sb.append(")");
-
-      return sb.toString();
-   }
-}
diff --git a/src/core/src/tonkadur/fate/v1/lang/computation/IndexedMergeComputation.java b/src/core/src/tonkadur/fate/v1/lang/computation/IndexedMergeComputation.java
deleted file mode 100644
index f9f8ae4..0000000
--- a/src/core/src/tonkadur/fate/v1/lang/computation/IndexedMergeComputation.java
+++ /dev/null
@@ -1,242 +0,0 @@
-package tonkadur.fate.v1.lang.computation;
-
-import java.util.ArrayList;
-import java.util.List;
-
-import tonkadur.parser.Origin;
-import tonkadur.parser.ParsingError;
-
-import tonkadur.fate.v1.lang.type.Type;
-import tonkadur.fate.v1.lang.type.LambdaType;
-import tonkadur.fate.v1.lang.type.CollectionType;
-
-import tonkadur.fate.v1.lang.meta.ComputationVisitor;
-import tonkadur.fate.v1.lang.meta.Computation;
-import tonkadur.fate.v1.lang.meta.Computation;
-import tonkadur.fate.v1.lang.meta.RecurrentChecks;
-
-public class IndexedMergeComputation extends Computation
-{
-   /***************************************************************************/
-   /**** MEMBERS **************************************************************/
-   /***************************************************************************/
-   protected final List<Computation> extra_params;
-   protected final Computation lambda_function;
-   protected final Computation collection_in_a;
-   protected final Computation default_a;
-   protected final Computation collection_in_b;
-   protected final Computation default_b;
-   protected final boolean to_set;
-
-   /***************************************************************************/
-   /**** PROTECTED ************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   protected IndexedMergeComputation
-   (
-      final Origin origin,
-      final Computation lambda_function,
-      final Computation collection_in_a,
-      final Computation default_a,
-      final Computation collection_in_b,
-      final Computation default_b,
-      final boolean to_set,
-      final List<Computation> extra_params,
-      final Type output_type
-   )
-   {
-      super(origin, output_type);
-
-      this.lambda_function = lambda_function;
-      this.collection_in_a = collection_in_a;
-      this.default_a = default_a;
-      this.collection_in_b = collection_in_b;
-      this.default_b = default_b;
-      this.to_set = to_set;
-      this.extra_params = extra_params;
-   }
-
-   /***************************************************************************/
-   /**** PUBLIC ***************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   public static IndexedMergeComputation build
-   (
-      final Origin origin,
-      final Computation lambda_function,
-      final Computation collection_in_a,
-      final Computation default_a,
-      final Computation collection_in_b,
-      final Computation default_b,
-      final boolean to_set,
-      final List<Computation> extra_params
-   )
-   throws Throwable
-   {
-      final List<Type> types_in;
-
-      types_in = new ArrayList<Type>();
-
-      if (default_a == null)
-      {
-         RecurrentChecks.assert_is_a_collection(collection_in_a);
-      }
-      else
-      {
-         RecurrentChecks.assert_is_a_collection_of(collection_in_a, default_a);
-      }
-
-      if (default_b == null)
-      {
-         RecurrentChecks.assert_is_a_collection(collection_in_b);
-      }
-      else
-      {
-         RecurrentChecks.assert_is_a_collection_of(collection_in_b, default_b);
-      }
-
-      types_in.add(Type.INT);
-
-      types_in.add
-      (
-         ((CollectionType) collection_in_a.get_type()).get_content_type()
-      );
-
-      if (default_b != null)
-      {
-         /*
-          * Safe-Mode: two indices.
-          * Unsafe-Mode: only one index, since out-of-bound means stopping.
-          */
-         types_in.add(Type.INT);
-      }
-
-      types_in.add
-      (
-         ((CollectionType) collection_in_b.get_type()).get_content_type()
-      );
-
-      for (final Computation c: extra_params)
-      {
-         types_in.add(c.get_type());
-      }
-
-      RecurrentChecks.assert_lambda_matches_types(lambda_function, types_in);
-
-      return
-         new IndexedMergeComputation
-         (
-            origin,
-            lambda_function,
-            collection_in_a,
-            default_a,
-            collection_in_b,
-            default_b,
-            to_set,
-            extra_params,
-            CollectionType.build
-            (
-               origin,
-               ((LambdaType) lambda_function.get_type()).get_return_type(),
-               to_set,
-               "auto generated"
-            )
-         );
-   }
-
-   /**** Accessors ************************************************************/
-   @Override
-   public void get_visited_by (final ComputationVisitor cv)
-   throws Throwable
-   {
-      cv.visit_indexed_merge(this);
-   }
-
-   public Computation get_lambda_function ()
-   {
-      return lambda_function;
-   }
-
-   public Computation get_collection_in_a ()
-   {
-      return collection_in_a;
-   }
-
-   public Computation get_default_a ()
-   {
-      return default_a;
-   }
-
-   public Computation get_collection_in_b ()
-   {
-      return collection_in_b;
-   }
-
-   public Computation get_default_b ()
-   {
-      return default_b;
-   }
-
-   public List<Computation> get_extra_parameters ()
-   {
-      return extra_params;
-   }
-
-   public boolean to_set ()
-   {
-      return to_set;
-   }
-
-   /**** Misc. ****************************************************************/
-   @Override
-   public String toString ()
-   {
-      final StringBuilder sb = new StringBuilder();
-
-      if (to_set)
-      {
-         sb.append("(IndexedMergeToSet ");
-      }
-      else
-      {
-         sb.append("(IndexedMergeToList ");
-      }
-
-      sb.append(lambda_function.toString());
-      sb.append(" ");
-      sb.append(collection_in_a.toString());
-      sb.append(" ");
-
-      if (default_a == null)
-      {
-         sb.append("null");
-      }
-      else
-      {
-         sb.append(default_a.toString());
-      }
-
-      sb.append(" ");
-      sb.append(collection_in_b.toString());
-      sb.append(" ");
-
-      if (default_b == null)
-      {
-         sb.append("null");
-      }
-      else
-      {
-         sb.append(default_b.toString());
-      }
-
-      for (final Computation c: extra_params)
-      {
-         sb.append(" ");
-         sb.append(c.toString());
-      }
-
-      sb.append(")");
-
-      return sb.toString();
-   }
-}
diff --git a/src/core/src/tonkadur/fate/v1/lang/computation/IndexedPartitionComputation.java b/src/core/src/tonkadur/fate/v1/lang/computation/IndexedPartitionComputation.java
deleted file mode 100644
index d192f36..0000000
--- a/src/core/src/tonkadur/fate/v1/lang/computation/IndexedPartitionComputation.java
+++ /dev/null
@@ -1,151 +0,0 @@
-package tonkadur.fate.v1.lang.computation;
-
-import java.util.Collections;
-import java.util.List;
-import java.util.ArrayList;
-
-import tonkadur.parser.Origin;
-import tonkadur.parser.ParsingError;
-
-import tonkadur.fate.v1.lang.type.CollectionType;
-import tonkadur.fate.v1.lang.type.ConsType;
-import tonkadur.fate.v1.lang.type.Type;
-
-import tonkadur.fate.v1.lang.meta.ComputationVisitor;
-import tonkadur.fate.v1.lang.meta.Computation;
-import tonkadur.fate.v1.lang.meta.Computation;
-import tonkadur.fate.v1.lang.meta.RecurrentChecks;
-
-public class IndexedPartitionComputation extends Computation
-{
-   /***************************************************************************/
-   /**** MEMBERS **************************************************************/
-   /***************************************************************************/
-   protected final List<Computation> extra_params;
-   protected final Computation lambda_function;
-   protected final Computation collection;
-
-   /***************************************************************************/
-   /**** PROTECTED ************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   protected IndexedPartitionComputation
-   (
-      final Origin origin,
-      final Computation lambda_function,
-      final Computation collection,
-      final List<Computation> extra_params,
-      final Type output_type
-   )
-   {
-      super(origin, output_type);
-
-      this.lambda_function = lambda_function;
-      this.collection = collection;
-      this.extra_params = extra_params;
-   }
-
-   /***************************************************************************/
-   /**** PUBLIC ***************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   public static IndexedPartitionComputation build
-   (
-      final Origin origin,
-      final Computation lambda_function,
-      final Computation collection,
-      final List<Computation> extra_params
-   )
-   throws Throwable
-   {
-      final Type type;
-      final List<Type> target_signature;
-
-      target_signature = new ArrayList<Type>();
-
-      RecurrentChecks.assert_is_a_collection(collection);
-
-      target_signature.add(Type.INT);
-
-      target_signature.add
-      (
-         ((CollectionType) collection.get_type()).get_content_type()
-      );
-
-      for (final Computation c: extra_params)
-      {
-         target_signature.add(c.get_type());
-      }
-
-      RecurrentChecks.assert_lambda_matches_types
-      (
-         lambda_function,
-         Type.BOOL,
-         target_signature
-      );
-
-      type =
-         new ConsType
-         (
-            origin,
-            collection.get_type(),
-            collection.get_type(),
-            "auto generated"
-         );
-
-      return
-         new IndexedPartitionComputation
-         (
-            origin,
-            lambda_function,
-            collection,
-            extra_params,
-            type
-         );
-   }
-
-   /**** Accessors ************************************************************/
-   @Override
-   public void get_visited_by (final ComputationVisitor cv)
-   throws Throwable
-   {
-      cv.visit_indexed_partition(this);
-   }
-
-   public Computation get_lambda_function ()
-   {
-      return lambda_function;
-   }
-
-   public Computation get_collection ()
-   {
-      return collection;
-   }
-
-   public List<Computation> get_extra_parameters ()
-   {
-      return extra_params;
-   }
-
-   /**** Misc. ****************************************************************/
-   @Override
-   public String toString ()
-   {
-      final StringBuilder sb = new StringBuilder();
-
-      sb.append("(IndexedPartition ");
-      sb.append(lambda_function.toString());
-      sb.append(" ");
-      sb.append(collection.toString());
-
-      for (final Computation c: extra_params)
-      {
-         sb.append(" ");
-         sb.append(c.toString());
-      }
-
-      sb.append(")");
-
-      return sb.toString();
-   }
-}
diff --git a/src/core/src/tonkadur/fate/v1/lang/computation/IsEmpty.java b/src/core/src/tonkadur/fate/v1/lang/computation/IsEmpty.java
deleted file mode 100644
index 054447b..0000000
--- a/src/core/src/tonkadur/fate/v1/lang/computation/IsEmpty.java
+++ /dev/null
@@ -1,81 +0,0 @@
-package tonkadur.fate.v1.lang.computation;
-
-import tonkadur.parser.Origin;
-import tonkadur.parser.ParsingError;
-
-import tonkadur.fate.v1.lang.type.Type;
-
-import tonkadur.fate.v1.lang.meta.ComputationVisitor;
-import tonkadur.fate.v1.lang.meta.Computation;
-import tonkadur.fate.v1.lang.meta.RecurrentChecks;
-
-public class IsEmpty extends Computation
-{
-   /***************************************************************************/
-   /**** MEMBERS **************************************************************/
-   /***************************************************************************/
-   protected final Computation collection;
-
-   /***************************************************************************/
-   /**** PROTECTED ************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   protected IsEmpty
-   (
-      final Origin origin,
-      final Computation collection
-   )
-   {
-      super(origin, Type.BOOL);
-
-      this.collection = collection;
-   }
-
-   /***************************************************************************/
-   /**** PUBLIC ***************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   public static IsEmpty build
-   (
-      final Origin origin,
-      final Computation collection
-   )
-   throws ParsingError
-   {
-      RecurrentChecks.assert_is_a_collection(collection);
-
-      return new IsEmpty(origin, collection);
-   }
-
-   /**** Accessors ************************************************************/
-   @Override
-   public void get_visited_by (final ComputationVisitor cv)
-   throws Throwable
-   {
-      cv.visit_is_empty(this);
-   }
-
-   public Computation get_collection ()
-   {
-      return collection;
-   }
-
-   /**** Misc. ****************************************************************/
-   @Override
-   public String toString ()
-   {
-      final StringBuilder sb = new StringBuilder();
-
-      sb.append("(IsEmpty");
-      sb.append(System.lineSeparator());
-      sb.append(System.lineSeparator());
-
-      sb.append("collection:");
-      sb.append(System.lineSeparator());
-      sb.append(collection.toString());
-
-      sb.append(")");
-
-      return sb.toString();
-   }
-}
diff --git a/src/core/src/tonkadur/fate/v1/lang/computation/IsMemberOperator.java b/src/core/src/tonkadur/fate/v1/lang/computation/IsMemberOperator.java
deleted file mode 100644
index e909213..0000000
--- a/src/core/src/tonkadur/fate/v1/lang/computation/IsMemberOperator.java
+++ /dev/null
@@ -1,96 +0,0 @@
-package tonkadur.fate.v1.lang.computation;
-
-import tonkadur.parser.Origin;
-import tonkadur.parser.ParsingError;
-
-import tonkadur.fate.v1.lang.type.Type;
-
-import tonkadur.fate.v1.lang.meta.ComputationVisitor;
-import tonkadur.fate.v1.lang.meta.Computation;
-import tonkadur.fate.v1.lang.meta.RecurrentChecks;
-
-public class IsMemberOperator extends Computation
-{
-   /***************************************************************************/
-   /**** MEMBERS **************************************************************/
-   /***************************************************************************/
-   protected final Computation element;
-   protected final Computation collection;
-
-   /***************************************************************************/
-   /**** PROTECTED ************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   protected IsMemberOperator
-   (
-      final Origin origin,
-      final Computation element,
-      final Computation collection
-   )
-   {
-      super(origin, Type.BOOL);
-
-      this.collection = collection;
-      this.element = element;
-   }
-
-   /***************************************************************************/
-   /**** PUBLIC ***************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   public static IsMemberOperator build
-   (
-      final Origin origin,
-      final Computation element,
-      final Computation collection
-   )
-   throws ParsingError
-   {
-      RecurrentChecks.assert_is_a_collection_of(collection, element);
-
-      return new IsMemberOperator(origin, element, collection);
-   }
-
-   /**** Accessors ************************************************************/
-   @Override
-   public void get_visited_by (final ComputationVisitor cv)
-   throws Throwable
-   {
-      cv.visit_is_member_operator(this);
-   }
-
-   public Computation get_collection ()
-   {
-      return collection;
-   }
-
-   public Computation get_element ()
-   {
-      return element;
-   }
-
-   /**** Misc. ****************************************************************/
-   @Override
-   public String toString ()
-   {
-      final StringBuilder sb = new StringBuilder();
-
-      sb.append("(IsMemberOperator");
-      sb.append(System.lineSeparator());
-      sb.append(System.lineSeparator());
-
-      sb.append("element:");
-      sb.append(System.lineSeparator());
-      sb.append(element.toString());
-      sb.append(System.lineSeparator());
-      sb.append(System.lineSeparator());
-
-      sb.append("collection:");
-      sb.append(System.lineSeparator());
-      sb.append(collection.toString());
-
-      sb.append(")");
-
-      return sb.toString();
-   }
-}
diff --git a/src/core/src/tonkadur/fate/v1/lang/computation/MapComputation.java b/src/core/src/tonkadur/fate/v1/lang/computation/MapComputation.java
deleted file mode 100644
index 86bd6e4..0000000
--- a/src/core/src/tonkadur/fate/v1/lang/computation/MapComputation.java
+++ /dev/null
@@ -1,144 +0,0 @@
-package tonkadur.fate.v1.lang.computation;
-
-import java.util.Collections;
-import java.util.List;
-import java.util.ArrayList;
-
-import tonkadur.parser.Origin;
-import tonkadur.parser.ParsingError;
-
-import tonkadur.fate.v1.lang.type.Type;
-import tonkadur.fate.v1.lang.type.LambdaType;
-import tonkadur.fate.v1.lang.type.CollectionType;
-
-import tonkadur.fate.v1.lang.meta.ComputationVisitor;
-import tonkadur.fate.v1.lang.meta.Computation;
-import tonkadur.fate.v1.lang.meta.Computation;
-import tonkadur.fate.v1.lang.meta.RecurrentChecks;
-
-public class MapComputation extends Computation
-{
-   /***************************************************************************/
-   /**** MEMBERS **************************************************************/
-   /***************************************************************************/
-   protected final List<Computation> extra_params;
-   protected final Computation lambda_function;
-   protected final Computation collection;
-
-   /***************************************************************************/
-   /**** PROTECTED ************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   protected MapComputation
-   (
-      final Origin origin,
-      final Computation lambda_function,
-      final Computation collection,
-      final List<Computation> extra_params,
-      final Type output_type
-   )
-   {
-      super(origin, output_type);
-
-      this.lambda_function = lambda_function;
-      this.collection = collection;
-      this.extra_params = extra_params;
-   }
-
-   /***************************************************************************/
-   /**** PUBLIC ***************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   public static MapComputation build
-   (
-      final Origin origin,
-      final Computation lambda_function,
-      final Computation collection,
-      final List<Computation> extra_params
-   )
-   throws ParsingError
-   {
-      final List<Type> target_signature;
-
-      target_signature = new ArrayList<Type>();
-
-      RecurrentChecks.assert_is_a_collection(collection);
-
-      target_signature.add
-      (
-         ((CollectionType) collection.get_type()).get_content_type()
-      );
-
-      for (final Computation c: extra_params)
-      {
-         target_signature.add(c.get_type());
-      }
-
-      RecurrentChecks.assert_lambda_matches_types
-      (
-         lambda_function,
-         target_signature
-      );
-
-      return
-         new MapComputation
-         (
-            origin,
-            lambda_function,
-            collection,
-            extra_params,
-            CollectionType.build
-            (
-               origin,
-               ((LambdaType) lambda_function.get_type()).get_return_type(),
-               ((CollectionType) collection.get_type()).is_set(),
-               "auto generated"
-            )
-         );
-   }
-
-   /**** Accessors ************************************************************/
-   @Override
-   public void get_visited_by (final ComputationVisitor cv)
-   throws Throwable
-   {
-      cv.visit_map(this);
-   }
-
-   public Computation get_lambda_function ()
-   {
-      return lambda_function;
-   }
-
-   public Computation get_collection ()
-   {
-      return collection;
-   }
-
-   public List<Computation> get_extra_parameters ()
-   {
-      return extra_params;
-   }
-
-   /**** Misc. ****************************************************************/
-   @Override
-   public String toString ()
-   {
-      final StringBuilder sb = new StringBuilder();
-
-      sb.append("(Map ");
-      sb.append(lambda_function.toString());
-      sb.append(" ");
-      sb.append(collection.toString());
-
-      for (final Computation c: extra_params)
-      {
-         sb.append(" ");
-         sb.append(c.toString());
-      }
-
-      sb.append(")");
-
-      return sb.toString();
-   }
-}
diff --git a/src/core/src/tonkadur/fate/v1/lang/computation/MergeComputation.java b/src/core/src/tonkadur/fate/v1/lang/computation/MergeComputation.java
deleted file mode 100644
index 4df3d3b..0000000
--- a/src/core/src/tonkadur/fate/v1/lang/computation/MergeComputation.java
+++ /dev/null
@@ -1,233 +0,0 @@
-package tonkadur.fate.v1.lang.computation;
-
-import java.util.ArrayList;
-import java.util.List;
-
-import tonkadur.parser.Origin;
-import tonkadur.parser.ParsingError;
-
-import tonkadur.fate.v1.lang.type.Type;
-import tonkadur.fate.v1.lang.type.LambdaType;
-import tonkadur.fate.v1.lang.type.CollectionType;
-
-import tonkadur.fate.v1.lang.instruction.Merge;
-
-import tonkadur.fate.v1.lang.meta.ComputationVisitor;
-import tonkadur.fate.v1.lang.meta.Computation;
-import tonkadur.fate.v1.lang.meta.Computation;
-import tonkadur.fate.v1.lang.meta.RecurrentChecks;
-
-public class MergeComputation extends Computation
-{
-   /***************************************************************************/
-   /**** MEMBERS **************************************************************/
-   /***************************************************************************/
-   protected final List<Computation> extra_params;
-   protected final Computation lambda_function;
-   protected final Computation collection_in_a;
-   protected final Computation default_a;
-   protected final Computation collection_in_b;
-   protected final Computation default_b;
-   protected final boolean to_set;
-
-   /***************************************************************************/
-   /**** PROTECTED ************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   protected MergeComputation
-   (
-      final Origin origin,
-      final Computation lambda_function,
-      final Computation collection_in_a,
-      final Computation default_a,
-      final Computation collection_in_b,
-      final Computation default_b,
-      final boolean to_set,
-      final List<Computation> extra_params,
-      final Type output_type
-   )
-   {
-      super(origin, output_type);
-
-      this.lambda_function = lambda_function;
-      this.collection_in_a = collection_in_a;
-      this.default_a = default_a;
-      this.collection_in_b = collection_in_b;
-      this.default_b = default_b;
-      this.to_set = to_set;
-      this.extra_params = extra_params;
-   }
-
-   /***************************************************************************/
-   /**** PUBLIC ***************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   public static MergeComputation build
-   (
-      final Origin origin,
-      final Computation lambda_function,
-      final Computation collection_in_a,
-      final Computation default_a,
-      final Computation collection_in_b,
-      final Computation default_b,
-      final boolean to_set,
-      final List<Computation> extra_params
-   )
-   throws Throwable
-   {
-      final List<Type> types_in;
-
-      types_in = new ArrayList<Type>();
-
-      if (default_a == null)
-      {
-         RecurrentChecks.assert_is_a_collection(collection_in_a);
-      }
-      else
-      {
-         RecurrentChecks.assert_is_a_collection_of(collection_in_a, default_a);
-      }
-
-      if (default_b == null)
-      {
-         RecurrentChecks.assert_is_a_collection(collection_in_b);
-      }
-      else
-      {
-         RecurrentChecks.assert_is_a_collection_of(collection_in_b, default_b);
-      }
-
-      types_in.add
-      (
-         ((CollectionType) collection_in_a.get_type()).get_content_type()
-      );
-
-      types_in.add
-      (
-         ((CollectionType) collection_in_b.get_type()).get_content_type()
-      );
-
-      for (final Computation c: extra_params)
-      {
-         types_in.add(c.get_type());
-      }
-
-      RecurrentChecks.assert_lambda_matches_types(lambda_function, types_in);
-
-      return
-         new MergeComputation
-         (
-            origin,
-            lambda_function,
-            collection_in_a,
-            default_a,
-            collection_in_b,
-            default_b,
-            to_set,
-            extra_params,
-            CollectionType.build
-            (
-               origin,
-               ((LambdaType) lambda_function.get_type()).get_return_type(),
-               to_set,
-               "auto generated"
-            )
-         );
-   }
-
-   /**** Accessors ************************************************************/
-   @Override
-   public void get_visited_by (final ComputationVisitor cv)
-   throws Throwable
-   {
-      cv.visit_merge(this);
-   }
-
-   public Computation get_lambda_function ()
-   {
-      return lambda_function;
-   }
-
-   public Computation get_collection_in_a ()
-   {
-      return collection_in_a;
-   }
-
-   public Computation get_default_a ()
-   {
-      return default_a;
-   }
-
-   public Computation get_collection_in_b ()
-   {
-      return collection_in_b;
-   }
-
-   public Computation get_default_b ()
-   {
-      return default_b;
-   }
-
-   public List<Computation> get_extra_parameters ()
-   {
-      return extra_params;
-   }
-
-   public boolean to_set ()
-   {
-      return to_set;
-   }
-
-   /**** Misc. ****************************************************************/
-   @Override
-   public String toString ()
-   {
-      final StringBuilder sb = new StringBuilder();
-
-      if (to_set)
-      {
-         sb.append("(MergeToSet ");
-      }
-      else
-      {
-         sb.append("(MergeToList ");
-      }
-
-      sb.append(lambda_function.toString());
-      sb.append(" ");
-      sb.append(collection_in_a.toString());
-      sb.append(" ");
-
-      if (default_a == null)
-      {
-         sb.append("null");
-      }
-      else
-      {
-         sb.append(default_a.toString());
-      }
-
-      sb.append(" ");
-      sb.append(collection_in_b.toString());
-      sb.append(" ");
-
-      if (default_b == null)
-      {
-         sb.append("null");
-      }
-      else
-      {
-         sb.append(default_b.toString());
-      }
-
-      for (final Computation c: extra_params)
-      {
-         sb.append(" ");
-         sb.append(c.toString());
-      }
-
-      sb.append(")");
-
-      return sb.toString();
-   }
-}
diff --git a/src/core/src/tonkadur/fate/v1/lang/computation/Operation.java b/src/core/src/tonkadur/fate/v1/lang/computation/Operation.java
deleted file mode 100644
index d83fe85..0000000
--- a/src/core/src/tonkadur/fate/v1/lang/computation/Operation.java
+++ /dev/null
@@ -1,188 +0,0 @@
-package tonkadur.fate.v1.lang.computation;
-
-import java.util.Collection;
-import java.util.List;
-
-import tonkadur.error.ErrorManager;
-
-import tonkadur.parser.Origin;
-
-//import tonkadur.fate.v1.error.ConflictingTypeException;
-import tonkadur.fate.v1.error.IncomparableTypeException;
-import tonkadur.fate.v1.error.IncompatibleTypeException;
-import tonkadur.fate.v1.error.InvalidArityException;
-import tonkadur.fate.v1.error.InvalidTypeException;
-
-import tonkadur.fate.v1.lang.type.Type;
-
-import tonkadur.fate.v1.lang.meta.ComputationVisitor;
-import tonkadur.fate.v1.lang.meta.Computation;
-
-public class Operation extends Computation
-{
-   protected final Operator operator;
-   protected final List<Computation> operands;
-
-   protected Operation
-   (
-      final Origin origin,
-      final Type result_type,
-      final Operator operator,
-      final List<Computation> operands
-   )
-   {
-      super(origin, result_type);
-
-      this.operator = operator;
-      this.operands = operands;
-   }
-
-   public static Operation build
-   (
-      final Origin origin,
-      final Operator operator,
-      final List<Computation> operands
-   )
-   throws
-      //ConflictingTypeException,
-      IncomparableTypeException,
-      IncompatibleTypeException,
-      InvalidArityException,
-      InvalidTypeException
-   {
-      final Collection<Type> allowed_base_types;
-      final int operator_max_arity;
-      final int operator_min_arity;
-      final int operands_size;
-      Type computed_type, previous_computed_type;
-
-      allowed_base_types = operator.get_allowed_base_types();
-      operator_max_arity = operator.get_maximum_arity();
-      operator_min_arity = operator.get_minimum_arity();
-      operands_size = operands.size();
-
-      if
-      (
-         (operands_size < operator_min_arity)
-         ||
-         (
-            (operator_max_arity != 0)
-            && (operator_max_arity < operands_size)
-         )
-      )
-      {
-         ErrorManager.handle
-         (
-            new InvalidArityException
-            (
-               origin,
-               operands_size,
-               operator_min_arity,
-               operator_max_arity
-            )
-         );
-      }
-
-      computed_type = operands.get(0).get_type();
-
-      for (final Computation operand: operands)
-      {
-         final Type operand_type;
-
-         operand_type = operand.get_type();
-
-         if (!allowed_base_types.contains(operand_type.get_act_as_type()))
-         {
-            ErrorManager.handle
-            (
-               new InvalidTypeException
-               (
-                  operand.get_origin(),
-                  operand_type,
-                  allowed_base_types
-               )
-            );
-         }
-
-         /*
-
-         if (computed_type.equals(operand_type))
-         {
-            continue;
-         }
-
-         ErrorManager.handle
-         (
-            new ConflictingTypeException
-            (
-               operand.get_origin(),
-               operand_type,
-               computed_type
-            )
-         );
-
-         */
-
-         if (operand_type.can_be_used_as(computed_type))
-         {
-            continue;
-         }
-
-         previous_computed_type = computed_type;
-         computed_type = computed_type.try_merging_with(operand_type);
-
-         if (computed_type != null)
-         {
-            continue;
-         }
-
-         ErrorManager.handle
-         (
-            new IncompatibleTypeException
-            (
-               operand.get_origin(),
-               operand_type,
-               previous_computed_type
-            )
-         );
-
-         computed_type =
-            (Type) previous_computed_type.generate_comparable_to(operand_type);
-
-         if (computed_type.equals(Type.ANY))
-         {
-            ErrorManager.handle
-            (
-               new IncomparableTypeException
-               (
-                  operand.get_origin(),
-                  operand_type,
-                  previous_computed_type
-               )
-            );
-         }
-      }
-
-      computed_type = operator.transform_type(computed_type);
-
-      return new Operation(origin, computed_type, operator, operands);
-   }
-
-   /**** Accessors ************************************************************/
-   @Override
-   public void get_visited_by (final ComputationVisitor cv)
-   throws Throwable
-   {
-      cv.visit_operation(this);
-   }
-
-   public Operator get_operator ()
-   {
-      return operator;
-   }
-
-   public List<Computation> get_operands ()
-   {
-      return operands;
-   }
-}
diff --git a/src/core/src/tonkadur/fate/v1/lang/computation/PartitionComputation.java b/src/core/src/tonkadur/fate/v1/lang/computation/PartitionComputation.java
deleted file mode 100644
index b240915..0000000
--- a/src/core/src/tonkadur/fate/v1/lang/computation/PartitionComputation.java
+++ /dev/null
@@ -1,149 +0,0 @@
-package tonkadur.fate.v1.lang.computation;
-
-import java.util.Collections;
-import java.util.List;
-import java.util.ArrayList;
-
-import tonkadur.parser.Origin;
-import tonkadur.parser.ParsingError;
-
-import tonkadur.fate.v1.lang.type.CollectionType;
-import tonkadur.fate.v1.lang.type.ConsType;
-import tonkadur.fate.v1.lang.type.Type;
-
-import tonkadur.fate.v1.lang.meta.ComputationVisitor;
-import tonkadur.fate.v1.lang.meta.Computation;
-import tonkadur.fate.v1.lang.meta.Computation;
-import tonkadur.fate.v1.lang.meta.RecurrentChecks;
-
-public class PartitionComputation extends Computation
-{
-   /***************************************************************************/
-   /**** MEMBERS **************************************************************/
-   /***************************************************************************/
-   protected final List<Computation> extra_params;
-   protected final Computation lambda_function;
-   protected final Computation collection;
-
-   /***************************************************************************/
-   /**** PROTECTED ************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   protected PartitionComputation
-   (
-      final Origin origin,
-      final Computation lambda_function,
-      final Computation collection,
-      final List<Computation> extra_params,
-      final Type output_type
-   )
-   {
-      super(origin, output_type);
-
-      this.lambda_function = lambda_function;
-      this.collection = collection;
-      this.extra_params = extra_params;
-   }
-
-   /***************************************************************************/
-   /**** PUBLIC ***************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   public static PartitionComputation build
-   (
-      final Origin origin,
-      final Computation lambda_function,
-      final Computation collection,
-      final List<Computation> extra_params
-   )
-   throws Throwable
-   {
-      final Type type;
-      final List<Type> target_signature;
-
-      target_signature = new ArrayList<Type>();
-
-      RecurrentChecks.assert_is_a_collection(collection);
-
-      target_signature.add
-      (
-         ((CollectionType) collection.get_type()).get_content_type()
-      );
-
-      for (final Computation c: extra_params)
-      {
-         target_signature.add(c.get_type());
-      }
-
-      RecurrentChecks.assert_lambda_matches_types
-      (
-         lambda_function,
-         Type.BOOL,
-         target_signature
-      );
-
-      type =
-         new ConsType
-         (
-            origin,
-            collection.get_type(),
-            collection.get_type(),
-            "auto generated"
-         );
-
-      return
-         new PartitionComputation
-         (
-            origin,
-            lambda_function,
-            collection,
-            extra_params,
-            type
-         );
-   }
-
-   /**** Accessors ************************************************************/
-   @Override
-   public void get_visited_by (final ComputationVisitor cv)
-   throws Throwable
-   {
-      cv.visit_partition(this);
-   }
-
-   public Computation get_lambda_function ()
-   {
-      return lambda_function;
-   }
-
-   public Computation get_collection ()
-   {
-      return collection;
-   }
-
-   public List<Computation> get_extra_parameters ()
-   {
-      return extra_params;
-   }
-
-   /**** Misc. ****************************************************************/
-   @Override
-   public String toString ()
-   {
-      final StringBuilder sb = new StringBuilder();
-
-      sb.append("(Partition ");
-      sb.append(lambda_function.toString());
-      sb.append(" ");
-      sb.append(collection.toString());
-
-      for (final Computation c: extra_params)
-      {
-         sb.append(" ");
-         sb.append(c.toString());
-      }
-
-      sb.append(")");
-
-      return sb.toString();
-   }
-}
diff --git a/src/core/src/tonkadur/fate/v1/lang/computation/PopElementComputation.java b/src/core/src/tonkadur/fate/v1/lang/computation/PopElementComputation.java
deleted file mode 100644
index 5d50018..0000000
--- a/src/core/src/tonkadur/fate/v1/lang/computation/PopElementComputation.java
+++ /dev/null
@@ -1,91 +0,0 @@
-package tonkadur.fate.v1.lang.computation;
-
-import tonkadur.parser.Origin;
-import tonkadur.parser.ParsingError;
-
-import tonkadur.fate.v1.lang.meta.ComputationVisitor;
-import tonkadur.fate.v1.lang.meta.Computation;
-import tonkadur.fate.v1.lang.meta.RecurrentChecks;
-
-public class PopElementComputation extends Computation
-{
-   /***************************************************************************/
-   /**** MEMBERS **************************************************************/
-   /***************************************************************************/
-   protected final Computation collection;
-   protected final boolean is_from_left;
-
-   /***************************************************************************/
-   /**** PROTECTED ************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   protected PopElementComputation
-   (
-      final Origin origin,
-      final Computation collection,
-      final boolean is_from_left
-   )
-   {
-      super(origin, collection.get_type());
-
-      this.collection = collection;
-      this.is_from_left = is_from_left;
-   }
-
-   /***************************************************************************/
-   /**** PUBLIC ***************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   public static PopElementComputation build
-   (
-      final Origin origin,
-      final Computation collection,
-      final boolean is_from_left
-   )
-   throws ParsingError
-   {
-      RecurrentChecks.assert_is_a_collection(collection);
-
-      return new PopElementComputation(origin, collection, is_from_left);
-   }
-
-   /**** Accessors ************************************************************/
-   @Override
-   public void get_visited_by (final ComputationVisitor cv)
-   throws Throwable
-   {
-      cv.visit_pop_element(this);
-   }
-
-   public Computation get_collection ()
-   {
-      return collection;
-   }
-
-   public boolean is_from_left ()
-   {
-      return is_from_left;
-   }
-
-   /**** Misc. ****************************************************************/
-   @Override
-   public String toString ()
-   {
-      final StringBuilder sb = new StringBuilder();
-
-      if (is_from_left)
-      {
-         sb.append("(PopLeftElement ");
-      }
-      else
-      {
-         sb.append("(PopRightElement ");
-      }
-
-      sb.append(collection.toString());
-
-      sb.append(")");
-
-      return sb.toString();
-   }
-}
diff --git a/src/core/src/tonkadur/fate/v1/lang/computation/PushElementComputation.java b/src/core/src/tonkadur/fate/v1/lang/computation/PushElementComputation.java
deleted file mode 100644
index f13e1c7..0000000
--- a/src/core/src/tonkadur/fate/v1/lang/computation/PushElementComputation.java
+++ /dev/null
@@ -1,116 +0,0 @@
-package tonkadur.fate.v1.lang.computation;
-
-import tonkadur.parser.Origin;
-import tonkadur.parser.ParsingError;
-
-import tonkadur.fate.v1.lang.meta.ComputationVisitor;
-import tonkadur.fate.v1.lang.meta.Computation;
-import tonkadur.fate.v1.lang.meta.RecurrentChecks;
-
-public class PushElementComputation extends Computation
-{
-   /***************************************************************************/
-   /**** MEMBERS **************************************************************/
-   /***************************************************************************/
-   protected final Computation element;
-   protected final Computation collection;
-   protected final boolean is_from_left;
-
-   /***************************************************************************/
-   /**** PROTECTED ************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   protected PushElementComputation
-   (
-      final Origin origin,
-      final Computation element,
-      final Computation collection,
-      final boolean is_from_left
-   )
-   {
-      super(origin, collection.get_type());
-
-      this.collection = collection;
-      this.element = element;
-      this.is_from_left = is_from_left;
-   }
-
-   /***************************************************************************/
-   /**** PUBLIC ***************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   public static PushElementComputation build
-   (
-      final Origin origin,
-      final Computation element,
-      final Computation collection,
-      final boolean is_from_left
-   )
-   throws ParsingError
-   {
-      return
-         new PushElementComputation
-         (
-            origin,
-            element,
-            collection,
-            is_from_left
-         );
-   }
-
-   /**** Accessors ************************************************************/
-   @Override
-   public void get_visited_by (final ComputationVisitor cv)
-   throws Throwable
-   {
-      cv.visit_push_element(this);
-   }
-
-   public Computation get_collection ()
-   {
-      return collection;
-   }
-
-   public Computation get_element ()
-   {
-      return element;
-   }
-
-   public boolean  is_from_left ()
-   {
-      return is_from_left;
-   }
-
-   /**** Misc. ****************************************************************/
-   @Override
-   public String toString ()
-   {
-      final StringBuilder sb = new StringBuilder();
-
-      if (is_from_left)
-      {
-         sb.append("(LeftPushElement");
-      }
-      else
-      {
-         sb.append("(RightPushElement");
-      }
-
-      sb.append(System.lineSeparator());
-      sb.append(System.lineSeparator());
-
-      sb.append("element:");
-      sb.append(System.lineSeparator());
-      sb.append(element.toString());
-      sb.append(System.lineSeparator());
-      sb.append(System.lineSeparator());
-
-      sb.append("collection:");
-      sb.append(System.lineSeparator());
-      sb.append(collection.toString());
-
-      sb.append(")");
-
-      return sb.toString();
-   }
-}
diff --git a/src/core/src/tonkadur/fate/v1/lang/computation/Range.java b/src/core/src/tonkadur/fate/v1/lang/computation/Range.java
deleted file mode 100644
index 736ecf7..0000000
--- a/src/core/src/tonkadur/fate/v1/lang/computation/Range.java
+++ /dev/null
@@ -1,109 +0,0 @@
-package tonkadur.fate.v1.lang.computation;
-
-import tonkadur.parser.Origin;
-import tonkadur.parser.ParsingError;
-
-import tonkadur.fate.v1.lang.type.CollectionType;
-import tonkadur.fate.v1.lang.type.Type;
-
-import tonkadur.fate.v1.lang.meta.ComputationVisitor;
-import tonkadur.fate.v1.lang.meta.Computation;
-import tonkadur.fate.v1.lang.meta.RecurrentChecks;
-
-public class Range extends Computation
-{
-   /***************************************************************************/
-   /**** MEMBERS **************************************************************/
-   /***************************************************************************/
-   protected final Computation start;
-   protected final Computation end;
-   protected final Computation increment;
-
-   /***************************************************************************/
-   /**** PROTECTED ************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   protected Range
-   (
-      final Origin origin,
-      final Computation start,
-      final Computation end,
-      final Computation increment,
-      final Type target_type
-   )
-   {
-      super(origin, target_type);
-
-      this.start = start;
-      this.end = end;
-      this.increment = increment;
-   }
-
-   /***************************************************************************/
-   /**** PUBLIC ***************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   public static Range build
-   (
-      final Origin origin,
-      final Computation start,
-      final Computation end,
-      final Computation increment
-   )
-   throws ParsingError
-   {
-      RecurrentChecks.assert_can_be_used_as(start, Type.INT);
-      RecurrentChecks.assert_can_be_used_as(end, Type.INT);
-      RecurrentChecks.assert_can_be_used_as(increment, Type.INT);
-
-      return
-         new Range
-         (
-            origin,
-            start,
-            end,
-            increment,
-            CollectionType.build(origin, Type.INT, false, "auto generated")
-         );
-   }
-
-   /**** Accessors ************************************************************/
-   @Override
-   public void get_visited_by (final ComputationVisitor cv)
-   throws Throwable
-   {
-      cv.visit_range(this);
-   }
-
-   public Computation get_start ()
-   {
-      return start;
-   }
-
-   public Computation get_end ()
-   {
-      return end;
-   }
-
-   public Computation get_increment ()
-   {
-      return increment;
-   }
-
-   /**** Misc. ****************************************************************/
-   @Override
-   public String toString ()
-   {
-      final StringBuilder sb = new StringBuilder();
-
-      sb.append("(Range ");
-      sb.append(start.toString());
-      sb.append(" ");
-      sb.append(end.toString());
-      sb.append(" ");
-      sb.append(increment.toString());
-      sb.append(")");
-
-      return sb.toString();
-   }
-}
diff --git a/src/core/src/tonkadur/fate/v1/lang/computation/RemoveAllOfElementComputation.java b/src/core/src/tonkadur/fate/v1/lang/computation/RemoveAllOfElementComputation.java
deleted file mode 100644
index a3fd529..0000000
--- a/src/core/src/tonkadur/fate/v1/lang/computation/RemoveAllOfElementComputation.java
+++ /dev/null
@@ -1,94 +0,0 @@
-package tonkadur.fate.v1.lang.computation;
-
-import tonkadur.parser.Origin;
-import tonkadur.parser.ParsingError;
-
-import tonkadur.fate.v1.lang.meta.ComputationVisitor;
-import tonkadur.fate.v1.lang.meta.Computation;
-import tonkadur.fate.v1.lang.meta.Computation;
-import tonkadur.fate.v1.lang.meta.RecurrentChecks;
-
-public class RemoveAllOfElementComputation extends Computation
-{
-   /***************************************************************************/
-   /**** MEMBERS **************************************************************/
-   /***************************************************************************/
-   protected final Computation element;
-   protected final Computation collection;
-
-   /***************************************************************************/
-   /**** PROTECTED ************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   protected RemoveAllOfElementComputation
-   (
-      final Origin origin,
-      final Computation element,
-      final Computation collection
-   )
-   {
-      super(origin, collection.get_type());
-
-      this.collection = collection;
-      this.element = element;
-   }
-   /***************************************************************************/
-   /**** PUBLIC ***************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   public static RemoveAllOfElementComputation build
-   (
-      final Origin origin,
-      final Computation element,
-      final Computation collection
-   )
-   throws ParsingError
-   {
-      RecurrentChecks.assert_is_a_collection_of(collection, element);
-
-      return new RemoveAllOfElementComputation(origin, element, collection);
-   }
-
-   /**** Accessors ************************************************************/
-   @Override
-   public void get_visited_by (final ComputationVisitor cv)
-   throws Throwable
-   {
-      cv.visit_remove_all_of_element(this);
-   }
-
-   public Computation get_element ()
-   {
-      return element;
-   }
-
-   public Computation get_collection ()
-   {
-      return collection;
-   }
-
-   /**** Misc. ****************************************************************/
-   @Override
-   public String toString ()
-   {
-      final StringBuilder sb = new StringBuilder();
-
-      sb.append("(RemoveAllOfElement");
-      sb.append(System.lineSeparator());
-      sb.append(System.lineSeparator());
-
-      sb.append("element:");
-      sb.append(System.lineSeparator());
-      sb.append(element.toString());
-      sb.append(System.lineSeparator());
-      sb.append(System.lineSeparator());
-
-      sb.append("collection:");
-      sb.append(System.lineSeparator());
-      sb.append(collection.toString());
-
-      sb.append(")");
-
-      return sb.toString();
-   }
-}
diff --git a/src/core/src/tonkadur/fate/v1/lang/computation/RemoveElementAtComputation.java b/src/core/src/tonkadur/fate/v1/lang/computation/RemoveElementAtComputation.java
deleted file mode 100644
index 4863992..0000000
--- a/src/core/src/tonkadur/fate/v1/lang/computation/RemoveElementAtComputation.java
+++ /dev/null
@@ -1,98 +0,0 @@
-package tonkadur.fate.v1.lang.computation;
-
-import tonkadur.parser.Origin;
-import tonkadur.parser.ParsingError;
-
-import tonkadur.fate.v1.lang.type.Type;
-
-import tonkadur.fate.v1.lang.meta.ComputationVisitor;
-import tonkadur.fate.v1.lang.meta.Computation;
-import tonkadur.fate.v1.lang.meta.Computation;
-import tonkadur.fate.v1.lang.meta.RecurrentChecks;
-
-public class RemoveElementAtComputation extends Computation
-{
-   /***************************************************************************/
-   /**** MEMBERS **************************************************************/
-   /***************************************************************************/
-   protected final Computation index;
-   protected final Computation collection;
-
-   /***************************************************************************/
-   /**** PROTECTED ************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   protected RemoveElementAtComputation
-   (
-      final Origin origin,
-      final Computation index,
-      final Computation collection
-   )
-   {
-      super(origin, collection.get_type());
-
-      this.collection = collection;
-      this.index = index;
-   }
-
-   /***************************************************************************/
-   /**** PUBLIC ***************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   public static RemoveElementAtComputation build
-   (
-      final Origin origin,
-      final Computation index,
-      final Computation collection
-   )
-   throws ParsingError
-   {
-      RecurrentChecks.assert_is_a_collection(collection);
-      RecurrentChecks.assert_can_be_used_as(index, Type.INT);
-
-      return new RemoveElementAtComputation(origin, index, collection);
-   }
-
-   /**** Accessors ************************************************************/
-   @Override
-   public void get_visited_by (final ComputationVisitor cv)
-   throws Throwable
-   {
-      cv.visit_remove_element_at(this);
-   }
-
-   public Computation get_index ()
-   {
-      return index;
-   }
-
-   public Computation get_collection ()
-   {
-      return collection;
-   }
-
-   /**** Misc. ****************************************************************/
-   @Override
-   public String toString ()
-   {
-      final StringBuilder sb = new StringBuilder();
-
-      sb.append("(RemoveElementAt");
-      sb.append(System.lineSeparator());
-      sb.append(System.lineSeparator());
-
-      sb.append("index:");
-      sb.append(System.lineSeparator());
-      sb.append(index.toString());
-      sb.append(System.lineSeparator());
-      sb.append(System.lineSeparator());
-
-      sb.append("collection:");
-      sb.append(System.lineSeparator());
-      sb.append(collection.toString());
-
-      sb.append(")");
-
-      return sb.toString();
-   }
-}
diff --git a/src/core/src/tonkadur/fate/v1/lang/computation/RemoveElementComputation.java b/src/core/src/tonkadur/fate/v1/lang/computation/RemoveElementComputation.java
deleted file mode 100644
index a484de3..0000000
--- a/src/core/src/tonkadur/fate/v1/lang/computation/RemoveElementComputation.java
+++ /dev/null
@@ -1,93 +0,0 @@
-package tonkadur.fate.v1.lang.computation;
-
-import tonkadur.parser.Origin;
-import tonkadur.parser.ParsingError;
-
-import tonkadur.fate.v1.lang.meta.ComputationVisitor;
-import tonkadur.fate.v1.lang.meta.Computation;
-import tonkadur.fate.v1.lang.meta.RecurrentChecks;
-
-public class RemoveElementComputation extends Computation
-{
-   /***************************************************************************/
-   /**** MEMBERS **************************************************************/
-   /***************************************************************************/
-   protected final Computation element;
-   protected final Computation collection;
-
-   /***************************************************************************/
-   /**** PROTECTED ************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   protected RemoveElementComputation
-   (
-      final Origin origin,
-      final Computation element,
-      final Computation collection
-   )
-   {
-      super(origin, collection.get_type());
-
-      this.collection = collection;
-      this.element = element;
-   }
-   /***************************************************************************/
-   /**** PUBLIC ***************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   public static RemoveElementComputation build
-   (
-      final Origin origin,
-      final Computation element,
-      final Computation collection
-   )
-   throws ParsingError
-   {
-      RecurrentChecks.assert_is_a_collection_of(collection, element);
-
-      return new RemoveElementComputation(origin, element, collection);
-   }
-
-   /**** Accessors ************************************************************/
-   @Override
-   public void get_visited_by (final ComputationVisitor cv)
-   throws Throwable
-   {
-      cv.visit_remove_element(this);
-   }
-
-   public Computation get_element ()
-   {
-      return element;
-   }
-
-   public Computation get_collection ()
-   {
-      return collection;
-   }
-
-   /**** Misc. ****************************************************************/
-   @Override
-   public String toString ()
-   {
-      final StringBuilder sb = new StringBuilder();
-
-      sb.append("(RemoveElement");
-      sb.append(System.lineSeparator());
-      sb.append(System.lineSeparator());
-
-      sb.append("element:");
-      sb.append(System.lineSeparator());
-      sb.append(element.toString());
-      sb.append(System.lineSeparator());
-      sb.append(System.lineSeparator());
-
-      sb.append("collection:");
-      sb.append(System.lineSeparator());
-      sb.append(collection.toString());
-
-      sb.append(")");
-
-      return sb.toString();
-   }
-}
diff --git a/src/core/src/tonkadur/fate/v1/lang/computation/RemoveElementsOfComputation.java b/src/core/src/tonkadur/fate/v1/lang/computation/RemoveElementsOfComputation.java
deleted file mode 100644
index f32acc4..0000000
--- a/src/core/src/tonkadur/fate/v1/lang/computation/RemoveElementsOfComputation.java
+++ /dev/null
@@ -1,105 +0,0 @@
-package tonkadur.fate.v1.lang.computation;
-
-import tonkadur.parser.Origin;
-import tonkadur.parser.ParsingError;
-
-import tonkadur.fate.v1.lang.type.CollectionType;
-
-import tonkadur.fate.v1.lang.meta.ComputationVisitor;
-import tonkadur.fate.v1.lang.meta.Computation;
-import tonkadur.fate.v1.lang.meta.RecurrentChecks;
-
-public class RemoveElementsOfComputation extends Computation
-{
-   /***************************************************************************/
-   /**** MEMBERS **************************************************************/
-   /***************************************************************************/
-   protected final Computation other_collection;
-   protected final Computation collection;
-
-   /***************************************************************************/
-   /**** PROTECTED ************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   protected RemoveElementsOfComputation
-   (
-      final Origin origin,
-      final Computation other_collection,
-      final Computation collection
-   )
-   {
-      super(origin, collection.get_type());
-
-      this.collection = collection;
-      this.other_collection = other_collection;
-   }
-
-   /***************************************************************************/
-   /**** PUBLIC ***************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   public static RemoveElementsOfComputation build
-   (
-      final Origin origin,
-      final Computation other_collection,
-      final Computation collection
-   )
-   throws ParsingError
-   {
-      RecurrentChecks.assert_is_a_collection(collection);
-      RecurrentChecks.assert_is_a_collection(other_collection);
-      RecurrentChecks.assert_can_be_used_as
-      (
-         other_collection.get_origin(),
-         ((CollectionType) other_collection.get_type()).get_content_type(),
-         ((CollectionType) collection.get_type()).get_content_type()
-      );
-
-      return
-         new RemoveElementsOfComputation(origin, other_collection, collection);
-   }
-
-   /**** Accessors ************************************************************/
-   @Override
-   public void get_visited_by (final ComputationVisitor cv)
-   throws Throwable
-   {
-      cv.visit_remove_elements_of(this);
-   }
-
-   public Computation get_source_collection ()
-   {
-      return other_collection;
-   }
-
-   public Computation get_target_collection ()
-   {
-      return collection;
-   }
-
-   /**** Misc. ****************************************************************/
-   @Override
-   public String toString ()
-   {
-      final StringBuilder sb = new StringBuilder();
-
-      sb.append("(RemoveElementsOf");
-      sb.append(System.lineSeparator());
-      sb.append(System.lineSeparator());
-
-      sb.append("other_collection:");
-      sb.append(System.lineSeparator());
-      sb.append(other_collection.toString());
-      sb.append(System.lineSeparator());
-      sb.append(System.lineSeparator());
-
-      sb.append("collection:");
-      sb.append(System.lineSeparator());
-      sb.append(collection.toString());
-
-      sb.append(")");
-
-      return sb.toString();
-   }
-
-}
diff --git a/src/core/src/tonkadur/fate/v1/lang/computation/ReverseListComputation.java b/src/core/src/tonkadur/fate/v1/lang/computation/ReverseListComputation.java
deleted file mode 100644
index 2d23e5c..0000000
--- a/src/core/src/tonkadur/fate/v1/lang/computation/ReverseListComputation.java
+++ /dev/null
@@ -1,90 +0,0 @@
-package tonkadur.fate.v1.lang.computation;
-
-import tonkadur.parser.Origin;
-import tonkadur.parser.ParsingError;
-
-import tonkadur.fate.v1.lang.type.CollectionType;
-import tonkadur.fate.v1.lang.type.Type;
-
-import tonkadur.fate.v1.lang.meta.ComputationVisitor;
-import tonkadur.fate.v1.lang.meta.Computation;
-import tonkadur.fate.v1.lang.meta.RecurrentChecks;
-
-public class ReverseListComputation extends Computation
-{
-   /***************************************************************************/
-   /**** MEMBERS **************************************************************/
-   /***************************************************************************/
-   protected final Computation collection;
-
-   /***************************************************************************/
-   /**** PROTECTED ************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   protected ReverseListComputation
-   (
-      final Origin origin,
-      final Computation collection,
-      final Type result_type
-   )
-   {
-      super(origin, result_type);
-
-      this.collection = collection;
-   }
-
-   /***************************************************************************/
-   /**** PUBLIC ***************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   public static ReverseListComputation build
-   (
-      final Origin origin,
-      final Computation collection
-   )
-   throws ParsingError
-   {
-      RecurrentChecks.assert_is_a_collection(collection);
-
-      return
-         new ReverseListComputation
-         (
-            origin,
-            collection,
-            CollectionType.build
-            (
-               origin,
-               (((CollectionType) collection.get_type()).get_content_type()),
-               false,
-               "auto generated"
-            )
-         );
-   }
-
-   /**** Accessors ************************************************************/
-   @Override
-   public void get_visited_by (final ComputationVisitor cv)
-   throws Throwable
-   {
-      cv.visit_reverse_list(this);
-   }
-
-   public Computation get_collection ()
-   {
-      return collection;
-   }
-
-   /**** Misc. ****************************************************************/
-   @Override
-   public String toString ()
-   {
-      final StringBuilder sb = new StringBuilder();
-
-      sb.append("(ReverseList ");
-      sb.append(collection.toString());
-
-      sb.append(")");
-
-      return sb.toString();
-   }
-}
diff --git a/src/core/src/tonkadur/fate/v1/lang/computation/ShuffleComputation.java b/src/core/src/tonkadur/fate/v1/lang/computation/ShuffleComputation.java
deleted file mode 100644
index 41a747e..0000000
--- a/src/core/src/tonkadur/fate/v1/lang/computation/ShuffleComputation.java
+++ /dev/null
@@ -1,90 +0,0 @@
-package tonkadur.fate.v1.lang.computation;
-
-import tonkadur.parser.Origin;
-import tonkadur.parser.ParsingError;
-
-import tonkadur.fate.v1.lang.type.CollectionType;
-import tonkadur.fate.v1.lang.type.Type;
-
-import tonkadur.fate.v1.lang.meta.ComputationVisitor;
-import tonkadur.fate.v1.lang.meta.Computation;
-import tonkadur.fate.v1.lang.meta.RecurrentChecks;
-
-public class ShuffleComputation extends Computation
-{
-   /***************************************************************************/
-   /**** MEMBERS **************************************************************/
-   /***************************************************************************/
-   protected final Computation collection;
-
-   /***************************************************************************/
-   /**** PROTECTED ************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   protected ShuffleComputation
-   (
-      final Origin origin,
-      final Computation collection,
-      final Type result_type
-   )
-   {
-      super(origin, result_type);
-
-      this.collection = collection;
-   }
-
-   /***************************************************************************/
-   /**** PUBLIC ***************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   public static ShuffleComputation build
-   (
-      final Origin origin,
-      final Computation collection
-   )
-   throws ParsingError
-   {
-      RecurrentChecks.assert_is_a_collection(collection);
-
-      return
-         new ShuffleComputation
-         (
-            origin,
-            collection,
-            CollectionType.build
-            (
-               origin,
-               (((CollectionType) collection.get_type()).get_content_type()),
-               false,
-               "auto generated"
-            )
-         );
-   }
-
-   /**** Accessors ************************************************************/
-   @Override
-   public void get_visited_by (final ComputationVisitor cv)
-   throws Throwable
-   {
-      cv.visit_shuffle(this);
-   }
-
-   public Computation get_collection ()
-   {
-      return collection;
-   }
-
-   /**** Misc. ****************************************************************/
-   @Override
-   public String toString ()
-   {
-      final StringBuilder sb = new StringBuilder();
-
-      sb.append("(Shuffle ");
-      sb.append(collection.toString());
-
-      sb.append(")");
-
-      return sb.toString();
-   }
-}
diff --git a/src/core/src/tonkadur/fate/v1/lang/computation/SizeOperator.java b/src/core/src/tonkadur/fate/v1/lang/computation/SizeOperator.java
deleted file mode 100644
index b0bf57f..0000000
--- a/src/core/src/tonkadur/fate/v1/lang/computation/SizeOperator.java
+++ /dev/null
@@ -1,81 +0,0 @@
-package tonkadur.fate.v1.lang.computation;
-
-import tonkadur.parser.Origin;
-import tonkadur.parser.ParsingError;
-
-import tonkadur.fate.v1.lang.type.Type;
-
-import tonkadur.fate.v1.lang.meta.ComputationVisitor;
-import tonkadur.fate.v1.lang.meta.Computation;
-import tonkadur.fate.v1.lang.meta.RecurrentChecks;
-
-public class SizeOperator extends Computation
-{
-   /***************************************************************************/
-   /**** MEMBERS **************************************************************/
-   /***************************************************************************/
-   protected final Computation collection;
-
-   /***************************************************************************/
-   /**** PROTECTED ************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   protected SizeOperator
-   (
-      final Origin origin,
-      final Computation collection
-   )
-   {
-      super(origin, Type.INT);
-
-      this.collection = collection;
-   }
-
-   /***************************************************************************/
-   /**** PUBLIC ***************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   public static SizeOperator build
-   (
-      final Origin origin,
-      final Computation collection
-   )
-   throws ParsingError
-   {
-      RecurrentChecks.assert_is_a_collection(collection);
-
-      return new SizeOperator(origin, collection);
-   }
-
-   /**** Accessors ************************************************************/
-   @Override
-   public void get_visited_by (final ComputationVisitor cv)
-   throws Throwable
-   {
-      cv.visit_size_operator(this);
-   }
-
-   public Computation get_collection ()
-   {
-      return collection;
-   }
-
-   /**** Misc. ****************************************************************/
-   @Override
-   public String toString ()
-   {
-      final StringBuilder sb = new StringBuilder();
-
-      sb.append("(SizeOperator");
-      sb.append(System.lineSeparator());
-      sb.append(System.lineSeparator());
-
-      sb.append("collection:");
-      sb.append(System.lineSeparator());
-      sb.append(collection.toString());
-
-      sb.append(")");
-
-      return sb.toString();
-   }
-}
diff --git a/src/core/src/tonkadur/fate/v1/lang/computation/SortComputation.java b/src/core/src/tonkadur/fate/v1/lang/computation/SortComputation.java
deleted file mode 100644
index ebb9279..0000000
--- a/src/core/src/tonkadur/fate/v1/lang/computation/SortComputation.java
+++ /dev/null
@@ -1,129 +0,0 @@
-package tonkadur.fate.v1.lang.computation;
-
-import java.util.ArrayList;
-import java.util.List;
-
-import tonkadur.parser.Origin;
-import tonkadur.parser.ParsingError;
-
-import tonkadur.fate.v1.lang.type.Type;
-import tonkadur.fate.v1.lang.type.CollectionType;
-
-import tonkadur.fate.v1.lang.instruction.Sort;
-
-import tonkadur.fate.v1.lang.meta.ComputationVisitor;
-import tonkadur.fate.v1.lang.meta.Computation;
-import tonkadur.fate.v1.lang.meta.Computation;
-import tonkadur.fate.v1.lang.meta.RecurrentChecks;
-
-public class SortComputation extends Computation
-{
-   /***************************************************************************/
-   /**** MEMBERS **************************************************************/
-   /***************************************************************************/
-   protected final List<Computation> extra_params;
-   protected final Computation lambda_function;
-   protected final Computation collection;
-
-   /***************************************************************************/
-   /**** PROTECTED ************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   protected SortComputation
-   (
-      final Origin origin,
-      final Computation lambda_function,
-      final Computation collection,
-      final List<Computation> extra_params
-   )
-   {
-      super(origin, collection.get_type());
-
-      this.lambda_function = lambda_function;
-      this.collection = collection;
-      this.extra_params = extra_params;
-   }
-
-   /***************************************************************************/
-   /**** PUBLIC ***************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   public static SortComputation build
-   (
-      final Origin origin,
-      final Computation lambda_function,
-      final Computation collection,
-      final List<Computation> extra_params
-   )
-   throws ParsingError
-   {
-      final List<Type> types_in;
-
-      types_in = new ArrayList<Type>();
-
-      RecurrentChecks.assert_is_a_list(collection);
-
-      types_in.add(((CollectionType) collection.get_type()).get_content_type());
-      types_in.add(types_in.get(0));
-
-      for (final Computation c: extra_params)
-      {
-         types_in.add(c.get_type());
-      }
-
-      RecurrentChecks.assert_lambda_matches_types
-      (
-         lambda_function,
-         Type.INT,
-         types_in
-      );
-
-      return
-         new SortComputation(origin, lambda_function, collection, extra_params);
-   }
-
-   /**** Accessors ************************************************************/
-   @Override
-   public void get_visited_by (final ComputationVisitor cv)
-   throws Throwable
-   {
-      cv.visit_sort(this);
-   }
-
-   public Computation get_lambda_function ()
-   {
-      return lambda_function;
-   }
-
-   public Computation get_collection ()
-   {
-      return collection;
-   }
-
-   public List<Computation> get_extra_parameters ()
-   {
-      return extra_params;
-   }
-
-   /**** Misc. ****************************************************************/
-   @Override
-   public String toString ()
-   {
-      final StringBuilder sb = new StringBuilder();
-
-      sb.append("(Sort ");
-      sb.append(lambda_function.toString());
-      sb.append(" ");
-      sb.append(collection.toString());
-
-      for (final Computation c: extra_params)
-      {
-         sb.append(" ");
-         sb.append(c.toString());
-      }
-
-      sb.append(")");
-
-      return sb.toString();
-   }
-}
diff --git a/src/core/src/tonkadur/fate/v1/lang/computation/SubListComputation.java b/src/core/src/tonkadur/fate/v1/lang/computation/SubListComputation.java
deleted file mode 100644
index 23304b1..0000000
--- a/src/core/src/tonkadur/fate/v1/lang/computation/SubListComputation.java
+++ /dev/null
@@ -1,100 +0,0 @@
-package tonkadur.fate.v1.lang.computation;
-
-import tonkadur.parser.Origin;
-import tonkadur.parser.ParsingError;
-
-import tonkadur.fate.v1.lang.type.Type;
-
-import tonkadur.fate.v1.lang.meta.ComputationVisitor;
-import tonkadur.fate.v1.lang.meta.Computation;
-import tonkadur.fate.v1.lang.meta.Computation;
-import tonkadur.fate.v1.lang.meta.RecurrentChecks;
-
-public class SubListComputation extends Computation
-{
-   /***************************************************************************/
-   /**** MEMBERS **************************************************************/
-   /***************************************************************************/
-   protected final Computation start;
-   protected final Computation end;
-   protected final Computation collection;
-
-   /***************************************************************************/
-   /**** PROTECTED ************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   protected SubListComputation
-   (
-      final Origin origin,
-      final Computation start,
-      final Computation end,
-      final Computation collection
-   )
-   {
-      super(origin, collection.get_type());
-
-      this.start = start;
-      this.end = end;
-      this.collection = collection;
-   }
-
-   /***************************************************************************/
-   /**** PUBLIC ***************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   public static SubListComputation build
-   (
-      final Origin origin,
-      final Computation start,
-      final Computation end,
-      final Computation collection
-   )
-   throws ParsingError
-   {
-      RecurrentChecks.assert_can_be_used_as(start, Type.INT);
-      RecurrentChecks.assert_can_be_used_as(end, Type.INT);
-      RecurrentChecks.assert_is_a_collection(collection);
-
-      return new SubListComputation(origin, start, end, collection);
-   }
-
-   /**** Accessors ************************************************************/
-   @Override
-   public void get_visited_by (final ComputationVisitor cv)
-   throws Throwable
-   {
-      cv.visit_sublist(this);
-   }
-
-   public Computation get_collection ()
-   {
-      return collection;
-   }
-
-   public Computation get_start_index ()
-   {
-      return start;
-   }
-
-   public Computation get_end_index ()
-   {
-      return end;
-   }
-
-   /**** Misc. ****************************************************************/
-   @Override
-   public String toString ()
-   {
-      final StringBuilder sb = new StringBuilder();
-
-      sb.append("(SubList ");
-      sb.append(start.toString());
-      sb.append(" ");
-      sb.append(end.toString());
-      sb.append(" ");
-      sb.append(collection.toString());
-      sb.append(")");
-
-      return sb.toString();
-   }
-}
diff --git a/src/core/src/tonkadur/fate/v1/lang/computation/TextJoin.java b/src/core/src/tonkadur/fate/v1/lang/computation/TextJoin.java
deleted file mode 100644
index 831bd8f..0000000
--- a/src/core/src/tonkadur/fate/v1/lang/computation/TextJoin.java
+++ /dev/null
@@ -1,102 +0,0 @@
-package tonkadur.fate.v1.lang.computation;
-
-import java.util.List;
-
-import tonkadur.parser.Origin;
-import tonkadur.parser.ParsingError;
-
-import tonkadur.fate.v1.lang.type.Type;
-
-import tonkadur.fate.v1.lang.meta.ComputationVisitor;
-import tonkadur.fate.v1.lang.meta.TextNode;
-import tonkadur.fate.v1.lang.meta.Computation;
-import tonkadur.fate.v1.lang.meta.RecurrentChecks;
-
-public class TextJoin extends TextNode
-{
-   /***************************************************************************/
-   /**** MEMBERS **************************************************************/
-   /***************************************************************************/
-   protected final Computation text_collection;
-   protected final Computation link;
-
-   /***************************************************************************/
-   /**** PROTECTED ************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   protected TextJoin
-   (
-      final Origin origin,
-      final Computation text_collection,
-      final Computation link
-   )
-   {
-      super(origin);
-
-      this.text_collection = text_collection;
-      this.link = link;
-   }
-
-   /***************************************************************************/
-   /**** PUBLIC ***************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   public static TextJoin build
-   (
-      final Origin origin,
-      final Computation text_collection,
-      final Computation link
-   )
-   throws ParsingError
-   {
-      RecurrentChecks.assert_is_a_collection_of
-      (
-         origin,
-         text_collection.get_type(),
-         origin,
-         Type.TEXT
-      );
-
-      RecurrentChecks.assert_can_be_used_as
-      (
-         link,
-         Type.TEXT
-      );
-
-      return new TextJoin (origin, text_collection, link);
-   }
-
-   /**** Accessors ************************************************************/
-   @Override
-   public void get_visited_by (final ComputationVisitor cv)
-   throws Throwable
-   {
-      cv.visit_text_join(this);
-   }
-
-   public Computation get_text_collection ()
-   {
-      return text_collection;
-   }
-
-   public Computation get_link ()
-   {
-      return link;
-   }
-
-   /**** Misc. ****************************************************************/
-   @Override
-   public String toString ()
-   {
-      final StringBuilder sb = new StringBuilder();
-
-      sb.append("(TextJoin ");
-      sb.append(link.toString());
-      sb.append(" ");
-      sb.append(text_collection.toString());
-
-      sb.append(")");
-
-      return sb.toString();
-   }
-}
diff --git a/src/core/src/tonkadur/fate/v1/lang/computation/VariableReference.java b/src/core/src/tonkadur/fate/v1/lang/computation/VariableReference.java
index 72b6068..6a8e428 100644
--- a/src/core/src/tonkadur/fate/v1/lang/computation/VariableReference.java
+++ b/src/core/src/tonkadur/fate/v1/lang/computation/VariableReference.java
@@ -5,11 +5,11 @@ import tonkadur.parser.Origin;
 import tonkadur.fate.v1.lang.Variable;
 
 import tonkadur.fate.v1.lang.meta.ComputationVisitor;
-import tonkadur.fate.v1.lang.meta.Reference;
+import tonkadur.fate.v1.lang.meta.Computation;
 
 import tonkadur.fate.v1.lang.type.Type;
 
-public class VariableReference extends Reference
+public class VariableReference extends Computation
 {
    /***************************************************************************/
    /**** MEMBERS **************************************************************/
@@ -26,7 +26,7 @@ public class VariableReference extends Reference
       final Variable variable
    )
    {
-      super(origin, reported_type, variable.get_name());
+      super(origin, reported_type);
       this.variable = variable;
    }
    /**** Constructors *********************************************************/
@@ -41,7 +41,7 @@ public class VariableReference extends Reference
       final Variable variable
    )
    {
-      super(origin, variable.get_type(), variable.get_name());
+      super(origin, variable.get_type());
       this.variable = variable;
    }
 
diff --git a/src/core/src/tonkadur/fate/v1/lang/computation/generic/AddressOperator.java b/src/core/src/tonkadur/fate/v1/lang/computation/generic/AddressOperator.java
new file mode 100644
index 0000000..5f51f1d
--- /dev/null
+++ b/src/core/src/tonkadur/fate/v1/lang/computation/generic/AddressOperator.java
@@ -0,0 +1,133 @@
+package tonkadur.fate.v1.lang.computation.generic;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import tonkadur.parser.Origin;
+
+import tonkadur.fate.v1.lang.type.PointerType;
+
+import tonkadur.fate.v1.lang.meta.ComputationVisitor;
+import tonkadur.fate.v1.lang.meta.Computation;
+
+import tonkadur.fate.v1.lang.computation.GenericComputation;
+import tonkadur.fate.v1.lang.computation.Constant;
+
+
+public class AddressOperator extends GenericComputation
+{
+   protected static final AddressOperator ARCHETYPE;
+
+   static
+   {
+      final List<String> aliases;
+
+      ARCHETYPE =
+         new AddressOperator
+         (
+            Origin.BASE_LANGUAGE,
+            Constant.build_boolean(Origin.BASE_LANGUAGE, true)
+         );
+
+      aliases = new ArrayList<String>();
+
+      aliases.add("address_of");
+      aliases.add("addressof");
+      aliases.add("addressOf");
+
+      aliases.add("address");
+      aliases.add("addr");
+
+      aliases.add("pointer_to");
+      aliases.add("pointerto");
+      aliases.add("pointerTo");
+
+      aliases.add("pointer");
+      aliases.add("ptr");
+
+      aliases.add("reference_to");
+      aliases.add("referenceto");
+      aliases.add("referenceTo");
+
+      aliases.add("reference");
+      aliases.add("ref");
+
+      try
+      {
+         ARCHETYPE.register(aliases, null);
+      }
+      catch (final Exception e)
+      {
+         e.printStackTrace();
+
+         System.exit(-1);
+      }
+   }
+
+   public static void initialize_class ()
+   {
+   }
+
+   /***************************************************************************/
+   /**** MEMBERS **************************************************************/
+   /***************************************************************************/
+   protected final Computation referred;
+
+   /***************************************************************************/
+   /**** PROTECTED ************************************************************/
+   /***************************************************************************/
+
+   /***************************************************************************/
+   /**** PUBLIC ***************************************************************/
+   /***************************************************************************/
+   /**** Constructors *********************************************************/
+   public AddressOperator (final Origin origin, final Computation referred)
+   {
+      super
+      (
+         origin,
+         new PointerType(origin, referred.get_type(), "auto generated"),
+         "address_of"
+      );
+
+      this.referred = referred;
+   }
+
+   @Override
+   public GenericComputation build
+   (
+      final Origin origin,
+      final List<Computation> call_parameters,
+      final Object _registered_parameter
+   )
+   throws Throwable
+   {
+      if (call_parameters.size() != 1)
+      {
+         // TODO: Error.
+      }
+
+      call_parameters.get(0).expect_non_string();
+
+      return new AddressOperator(origin, call_parameters.get(0));
+   }
+
+   /**** Accessors ************************************************************/
+   public Computation get_target ()
+   {
+      return referred;
+   }
+
+   /**** Misc. ****************************************************************/
+   @Override
+   public String toString ()
+   {
+      final StringBuilder sb = new StringBuilder();
+
+      sb.append("(AddressOf ");
+      sb.append(referred.toString());
+      sb.append(") ");
+
+      return sb.toString();
+   }
+}
diff --git a/src/core/src/tonkadur/fate/v1/lang/computation/AtReference.java b/src/core/src/tonkadur/fate/v1/lang/computation/generic/AtReference.java
index 7ae1e1f..ec81da7 100644
--- a/src/core/src/tonkadur/fate/v1/lang/computation/AtReference.java
+++ b/src/core/src/tonkadur/fate/v1/lang/computation/generic/AtReference.java
@@ -1,6 +1,8 @@
-package tonkadur.fate.v1.lang.computation;
+package tonkadur.fate.v1.lang.computation.generic;
 
 import java.util.Collections;
+import java.util.List;
+import java.util.ArrayList;
 
 import tonkadur.parser.Origin;
 
@@ -9,17 +11,63 @@ import tonkadur.error.ErrorManager;
 import tonkadur.fate.v1.error.InvalidTypeException;
 import tonkadur.fate.v1.error.UnknownStructureFieldException;
 
+
 import tonkadur.fate.v1.lang.Variable;
 
 import tonkadur.fate.v1.lang.meta.ComputationVisitor;
-import tonkadur.fate.v1.lang.meta.Reference;
 import tonkadur.fate.v1.lang.meta.Computation;
 
 import tonkadur.fate.v1.lang.type.PointerType;
 import tonkadur.fate.v1.lang.type.Type;
 
-public class AtReference extends Reference
+import tonkadur.fate.v1.lang.computation.Default;
+import tonkadur.fate.v1.lang.computation.GenericComputation;
+
+public class AtReference extends GenericComputation
 {
+   protected static final AtReference ARCHETYPE;
+
+   static
+   {
+      final List<String> aliases;
+
+      ARCHETYPE =
+         new AtReference
+         (
+            Origin.BASE_LANGUAGE,
+            Type.INT,
+            new Default
+            (
+               Origin.BASE_LANGUAGE,
+               new PointerType
+               (
+                  Origin.BASE_LANGUAGE,
+                  Type.INT,
+                  "(ptr int)"
+               )
+            )
+         );
+
+      aliases = new ArrayList<String>();
+
+      aliases.add("at");
+
+      try
+      {
+         ARCHETYPE.register(aliases, null);
+      }
+      catch (final Exception e)
+      {
+         e.printStackTrace();
+
+         System.exit(-1);
+      }
+   }
+
+   public static void initialize_class ()
+   {
+   }
+
    /***************************************************************************/
    /**** MEMBERS **************************************************************/
    /***************************************************************************/
@@ -35,7 +83,7 @@ public class AtReference extends Reference
       final Computation parent
    )
    {
-      super(origin, reported_type, ("(At " + parent.toString() + ")"));
+      super(origin, reported_type, "at");
 
       this.parent = parent;
    }
@@ -45,16 +93,24 @@ public class AtReference extends Reference
    /**** PUBLIC ***************************************************************/
    /***************************************************************************/
    /**** Constructors *********************************************************/
-   public static AtReference build
+   @Override
+   public GenericComputation build
    (
       final Origin origin,
-      final Computation parent
+      final List<Computation> call_parameters,
+      final Object _registered_parameter
    )
-   throws
-      InvalidTypeException
+   throws Throwable
    {
       Type current_type;
 
+      if (call_parameters.size() != 1)
+      {
+         // TODO: Error.
+      }
+
+      call_parameters.get(0).expect_non_string();
+
       current_type = parent.get_type();
 
       if (!(current_type instanceof PointerType))
@@ -80,13 +136,6 @@ public class AtReference extends Reference
    }
 
    /**** Accessors ************************************************************/
-   @Override
-   public void get_visited_by (final ComputationVisitor cv)
-   throws Throwable
-   {
-      cv.visit_at_reference(this);
-   }
-
    public Computation get_parent ()
    {
       return parent;
diff --git a/src/core/src/tonkadur/fate/v1/lang/computation/LambdaEvaluation.java b/src/core/src/tonkadur/fate/v1/lang/computation/generic/LambdaEvaluation.java
index fc66a49..dc5fcb5 100644
--- a/src/core/src/tonkadur/fate/v1/lang/computation/LambdaEvaluation.java
+++ b/src/core/src/tonkadur/fate/v1/lang/computation/generic/LambdaEvaluation.java
@@ -1,10 +1,13 @@
 package tonkadur.fate.v1.lang.computation;
 
 import java.util.List;
+import java.util.ArrayList;
 
 import tonkadur.parser.Origin;
 import tonkadur.parser.ParsingError;
 
+import tonkadur.functional.Merge;
+
 import tonkadur.fate.v1.lang.type.Type;
 import tonkadur.fate.v1.lang.type.LambdaType;
 
@@ -12,8 +15,40 @@ import tonkadur.fate.v1.lang.meta.ComputationVisitor;
 import tonkadur.fate.v1.lang.meta.Computation;
 import tonkadur.fate.v1.lang.meta.RecurrentChecks;
 
-public class LambdaEvaluation extends Computation
+public class LambdaEvaluation extends GenericComputation
 {
+   protected static final LambdaEvaluation ARCHETYPE;
+
+   static
+   {
+      final List<String> aliases;
+
+      ARCHETYPE =
+         new LambdaEvaluation
+         (
+            Origin.BASE_LANGUAGE,
+            null,
+            null,
+            Type.BOOL
+         );
+
+      aliases = new ArrayList<String>();
+
+      aliases.add("eval");
+      aliases.add("evaluate");
+
+      try
+      {
+         ARCHETYPE.register(aliases, null);
+      }
+      catch (final Exception e)
+      {
+         e.printStackTrace();
+
+         System.exit(-1);
+      }
+   }
+
    /***************************************************************************/
    /**** MEMBERS **************************************************************/
    /***************************************************************************/
@@ -32,7 +67,7 @@ public class LambdaEvaluation extends Computation
       final Type act_as
    )
    {
-      super(origin, act_as);
+      super(origin, act_as, "eval");
 
       this.lambda_function = lambda_function;
       this.parameters = parameters;
@@ -42,18 +77,65 @@ public class LambdaEvaluation extends Computation
    /**** PUBLIC ***************************************************************/
    /***************************************************************************/
    /**** Constructors *********************************************************/
-   public static LambdaEvaluation build
+   @Override
+   public GenericComputation build
    (
       final Origin origin,
-      final Computation lambda_function,
-      final List<Computation> parameters
+      final List<Computation> call_parameters,
+      final Object _registered_parameter
    )
-   throws ParsingError
+   throws Throwable
    {
-      RecurrentChecks.assert_lambda_matches_computations
+      final Computation lambda_function;
+      final List<Type> lambda_signature;
+
+      if (call_parameters.size() < 1)
+      {
+         // TODO: Error.
+      }
+
+      lambda_function = call_parameters.get(0);
+
+      lambda_function.expect_non_string();
+
+      RecurrentChecks.assert_is_a_lambda_function(lambda_function);
+
+      lambda_signature =
+         ((LambdaType) lambda_function.get_type()).get_signature();
+
+      call_parameters.remove(0);
+
+      /* String vs Variable resolution */
+      try
+      {
+         (new Merge<Type, Computation, Boolean>()
+         {
+            @Override
+            public Boolean risky_lambda (final Type t, final Computation p)
+            throws ParsingError
+            {
+               if (t.can_be_used_as(Type.STRING))
+               {
+                  p.expect_string();
+               }
+               else
+               {
+                  p.expect_non_string();
+               }
+               return Boolean.TRUE;
+            }
+         }).risky_merge(lambda_signature, call_parameters);
+      }
+      catch (final Throwable e)
+      {
+         // Will be handled better in the check below.
+      }
+
+      RecurrentChecks.assert_computations_matches_signature
       (
-         lambda_function,
-         parameters
+         origin,
+         call_parameters,
+         lambda_signature
       );
 
       return
@@ -67,13 +149,6 @@ public class LambdaEvaluation extends Computation
    }
 
    /**** Accessors ************************************************************/
-   @Override
-   public void get_visited_by (final ComputationVisitor cv)
-   throws Throwable
-   {
-      cv.visit_lambda_evaluation(this);
-   }
-
    public Computation get_lambda_function ()
    {
       return lambda_function;
diff --git a/src/core/src/tonkadur/fate/v1/lang/computation/generic/Operation.java b/src/core/src/tonkadur/fate/v1/lang/computation/generic/Operation.java
new file mode 100644
index 0000000..48cf0a9
--- /dev/null
+++ b/src/core/src/tonkadur/fate/v1/lang/computation/generic/Operation.java
@@ -0,0 +1,628 @@
+package tonkadur.fate.v1.lang.computation.generic;
+
+import java.util.Collection;
+import java.util.List;
+import java.util.ArrayList;
+
+import tonkadur.error.ErrorManager;
+
+import tonkadur.parser.Origin;
+
+//import tonkadur.fate.v1.error.ConflictingTypeException;
+import tonkadur.fate.v1.error.IncomparableTypeException;
+import tonkadur.fate.v1.error.IncompatibleTypeException;
+import tonkadur.fate.v1.error.InvalidArityException;
+import tonkadur.fate.v1.error.InvalidTypeException;
+
+import tonkadur.fate.v1.lang.type.Type;
+
+import tonkadur.fate.v1.lang.meta.ComputationVisitor;
+import tonkadur.fate.v1.lang.meta.Computation;
+import tonkadur.fate.v1.lang.meta.Computation;
+
+import tonkadur.fate.v1.lang.computation.GenericComputation;
+import tonkadur.fate.v1.lang.computation.Operator;
+import tonkadur.fate.v1.lang.computation.Constant;
+
+public class Operation extends GenericComputation
+{
+   protected static final Operation ARCHETYPE;
+
+   static
+   {
+      final List<Computation> operands;
+      List<String> aliases;
+
+      operands = new ArrayList<Computation>();
+
+      operands.add
+      (
+         Constant.build_boolean
+         (
+            Origin.BASE_LANGUAGE,
+            false
+         )
+      );
+
+      operands.add(operands.get(0));
+
+      ARCHETYPE =
+         new Operation
+         (
+            Origin.BASE_LANGUAGE,
+            Type.BOOL,
+            Operator.AND,
+            operands
+         );
+
+      /**** PLUS **************************************************************/
+      aliases = new ArrayList<String>();
+
+      aliases.add("+");
+      aliases.add("plus");
+
+      try
+      {
+         ARCHETYPE.register(aliases, Operator.PLUS);
+      }
+      catch (final Exception e)
+      {
+         e.printStackTrace();
+
+         System.exit(-1);
+      }
+
+      /**** MINUS *************************************************************/
+      aliases = new ArrayList<String>();
+
+      aliases.add("-");
+      aliases.add("minus");
+
+      try
+      {
+         ARCHETYPE.register(aliases, Operator.MINUS);
+      }
+      catch (final Exception e)
+      {
+         e.printStackTrace();
+
+         System.exit(-1);
+      }
+
+      /**** TIMES *************************************************************/
+      aliases = new ArrayList<String>();
+
+      aliases.add("*");
+      aliases.add("times");
+
+      try
+      {
+         ARCHETYPE.register(aliases, Operator.TIMES);
+      }
+      catch (final Exception e)
+      {
+         e.printStackTrace();
+
+         System.exit(-1);
+      }
+
+      /**** DIVIDE ************************************************************/
+      aliases = new ArrayList<String>();
+
+      aliases.add("/");
+      aliases.add("div");
+      aliases.add("divide");
+
+      try
+      {
+         ARCHETYPE.register(aliases, Operator.DIVIDE);
+      }
+      catch (final Exception e)
+      {
+         e.printStackTrace();
+
+         System.exit(-1);
+      }
+
+      /**** POWER *************************************************************/
+      aliases = new ArrayList<String>();
+
+      aliases.add("**");
+      aliases.add("^");
+      aliases.add("pow");
+      aliases.add("power");
+
+      try
+      {
+         ARCHETYPE.register(aliases, Operator.POWER);
+      }
+      catch (final Exception e)
+      {
+         e.printStackTrace();
+
+         System.exit(-1);
+      }
+
+      /**** MODULO ************************************************************/
+      aliases = new ArrayList<String>();
+
+      aliases.add("%");
+      aliases.add("mod");
+      aliases.add("modulo");
+
+      try
+      {
+         ARCHETYPE.register(aliases, Operator.MODULO);
+      }
+      catch (final Exception e)
+      {
+         e.printStackTrace();
+
+         System.exit(-1);
+      }
+
+      /**** MIN ***************************************************************/
+      aliases = new ArrayList<String>();
+
+      aliases.add("min");
+      aliases.add("minimum");
+
+      try
+      {
+         ARCHETYPE.register(aliases, Operator.MIN);
+      }
+      catch (final Exception e)
+      {
+         e.printStackTrace();
+
+         System.exit(-1);
+      }
+
+      /**** MAX ***************************************************************/
+      aliases = new ArrayList<String>();
+
+      aliases.add("max");
+      aliases.add("maximum");
+
+      try
+      {
+         ARCHETYPE.register(aliases, Operator.MAX);
+      }
+      catch (final Exception e)
+      {
+         e.printStackTrace();
+
+         System.exit(-1);
+      }
+
+      /**** CLAMP *************************************************************/
+      aliases = new ArrayList<String>();
+
+      aliases.add("clamp");
+
+      try
+      {
+         ARCHETYPE.register(aliases, Operator.CLAMP);
+      }
+      catch (final Exception e)
+      {
+         e.printStackTrace();
+
+         System.exit(-1);
+      }
+
+      /**** ABS ***************************************************************/
+      aliases = new ArrayList<String>();
+
+      aliases.add("abs");
+      aliases.add("absolute");
+
+      try
+      {
+         ARCHETYPE.register(aliases, Operator.ABS);
+      }
+      catch (final Exception e)
+      {
+         e.printStackTrace();
+
+         System.exit(-1);
+      }
+
+      /**** RANDOM ************************************************************/
+      aliases = new ArrayList<String>();
+
+      aliases.add("rnd");
+      aliases.add("rand");
+      aliases.add("random");
+
+      try
+      {
+         ARCHETYPE.register(aliases, Operator.RANDOM);
+      }
+      catch (final Exception e)
+      {
+         e.printStackTrace();
+
+         System.exit(-1);
+      }
+
+      /**** AND ***************************************************************/
+      aliases = new ArrayList<String>();
+
+      aliases.add("and");
+      aliases.add("/\\");
+
+      try
+      {
+         ARCHETYPE.register(aliases, Operator.AND);
+      }
+      catch (final Exception e)
+      {
+         e.printStackTrace();
+
+         System.exit(-1);
+      }
+
+      /**** OR ****************************************************************/
+      aliases = new ArrayList<String>();
+
+      aliases.add("or");
+      aliases.add("\\/");
+
+      try
+      {
+         ARCHETYPE.register(aliases, Operator.OR);
+      }
+      catch (final Exception e)
+      {
+         e.printStackTrace();
+
+         System.exit(-1);
+      }
+
+      /**** NOT ***************************************************************/
+      aliases = new ArrayList<String>();
+
+      aliases.add("not");
+      aliases.add("~");
+      aliases.add("!");
+
+      try
+      {
+         ARCHETYPE.register(aliases, Operator.NOT);
+      }
+      catch (final Exception e)
+      {
+         e.printStackTrace();
+
+         System.exit(-1);
+      }
+
+      /**** IMPLIES ***********************************************************/
+      aliases = new ArrayList<String>();
+
+      aliases.add("implies");
+      aliases.add("=>");
+      aliases.add("->");
+
+      try
+      {
+         ARCHETYPE.register(aliases, Operator.IMPLIES);
+      }
+      catch (final Exception e)
+      {
+         e.printStackTrace();
+
+         System.exit(-1);
+      }
+
+      /**** ONE IN ************************************************************/
+      aliases = new ArrayList<String>();
+
+      aliases.add("exactlyOneIn");
+      aliases.add("exactlyonein");
+      aliases.add("exactly_one_in");
+      aliases.add("OneIn");
+      aliases.add("onein");
+      aliases.add("one_in");
+
+      try
+      {
+         ARCHETYPE.register(aliases, Operator.ONE_IN);
+      }
+      catch (final Exception e)
+      {
+         e.printStackTrace();
+
+         System.exit(-1);
+      }
+
+      /**** EQUALS ************************************************************/
+      aliases = new ArrayList<String>();
+
+      aliases.add("equals");
+      aliases.add("eq");
+      aliases.add("=");
+      aliases.add("==");
+
+      try
+      {
+         ARCHETYPE.register(aliases, Operator.EQUALS);
+      }
+      catch (final Exception e)
+      {
+         e.printStackTrace();
+
+         System.exit(-1);
+      }
+
+      /**** LOWER THAN ********************************************************/
+      aliases = new ArrayList<String>();
+
+      aliases.add("lowerThan");
+      aliases.add("lowerthan");
+      aliases.add("lower_than");
+      aliases.add("lt");
+      aliases.add("<");
+
+      try
+      {
+         ARCHETYPE.register(aliases, Operator.LOWER_THAN);
+      }
+      catch (final Exception e)
+      {
+         e.printStackTrace();
+
+         System.exit(-1);
+      }
+
+      /**** LOWER EQUAL THAN **************************************************/
+      aliases = new ArrayList<String>();
+
+      aliases.add("lowerEqualThan");
+      aliases.add("lowerequalthan");
+      aliases.add("lower_equal_than");
+      aliases.add("le");
+      aliases.add("<=");
+      aliases.add("=<");
+
+      try
+      {
+         ARCHETYPE.register(aliases, Operator.LOWER_EQUAL_THAN);
+      }
+      catch (final Exception e)
+      {
+         e.printStackTrace();
+
+         System.exit(-1);
+      }
+
+      /**** GREATER EQUAL THAN **************************************************/
+      aliases = new ArrayList<String>();
+
+      aliases.add("greaterEqualThan");
+      aliases.add("greaterequalthan");
+      aliases.add("greater_equal_than");
+      aliases.add("ge");
+      aliases.add(">=");
+
+      try
+      {
+         ARCHETYPE.register(aliases, Operator.GREATER_EQUAL_THAN);
+      }
+      catch (final Exception e)
+      {
+         e.printStackTrace();
+
+         System.exit(-1);
+      }
+
+      /**** GREATER THAN ******************************************************/
+      aliases = new ArrayList<String>();
+
+      aliases.add("greaterThan");
+      aliases.add("greaterthan");
+      aliases.add("greater_than");
+      aliases.add("gt");
+      aliases.add(">");
+
+      try
+      {
+         ARCHETYPE.register(aliases, Operator.GREATER_THAN);
+      }
+      catch (final Exception e)
+      {
+         e.printStackTrace();
+
+         System.exit(-1);
+      }
+   }
+
+   public static void initialize_class ()
+   {
+   }
+
+   /***************************************************************************/
+   /**** MEMBERS **************************************************************/
+   /***************************************************************************/
+   protected final Operator operator;
+   protected final List<Computation> operands;
+
+   /***************************************************************************/
+   /**** PROTECTED ************************************************************/
+   /***************************************************************************/
+   protected Operation
+   (
+      final Origin origin,
+      final Type result_type,
+      final Operator operator,
+      final List<Computation> operands
+   )
+   {
+      super(origin, result_type, "+");
+
+      this.operator = operator;
+      this.operands = operands;
+   }
+
+   @Override
+   public GenericComputation build
+   (
+      final Origin origin,
+      final List<Computation> operands,
+      final Object registered_parameter
+   )
+   throws Throwable
+   {
+      final Operator operator;
+      final Collection<Type> allowed_base_types;
+      final int operator_max_arity;
+      final int operator_min_arity;
+      final int operands_size;
+      Type computed_type, previous_computed_type;
+
+      operator = (Operator) registered_parameter;
+
+      allowed_base_types = operator.get_allowed_base_types();
+      operator_max_arity = operator.get_maximum_arity();
+      operator_min_arity = operator.get_minimum_arity();
+      operands_size = operands.size();
+
+      if
+      (
+         (operands_size < operator_min_arity)
+         ||
+         (
+            (operator_max_arity != 0)
+            && (operator_max_arity < operands_size)
+         )
+      )
+      {
+         ErrorManager.handle
+         (
+            new InvalidArityException
+            (
+               origin,
+               operands_size,
+               operator_min_arity,
+               operator_max_arity
+            )
+         );
+      }
+
+      computed_type = operands.get(0).get_type();
+
+      for (final Computation operand: operands)
+      {
+         final Type operand_type;
+
+         operand_type = operand.get_type();
+
+         if (!allowed_base_types.contains(operand_type.get_act_as_type()))
+         {
+            ErrorManager.handle
+            (
+               new InvalidTypeException
+               (
+                  operand.get_origin(),
+                  operand_type,
+                  allowed_base_types
+               )
+            );
+         }
+
+         /*
+
+         if (computed_type.equals(operand_type))
+         {
+            continue;
+         }
+
+         ErrorManager.handle
+         (
+            new ConflictingTypeException
+            (
+               operand.get_origin(),
+               operand_type,
+               computed_type
+            )
+         );
+
+         */
+
+         if (operand_type.can_be_used_as(computed_type))
+         {
+            continue;
+         }
+
+         previous_computed_type = computed_type;
+         computed_type = computed_type.try_merging_with(operand_type);
+
+         if (computed_type != null)
+         {
+            continue;
+         }
+
+         ErrorManager.handle
+         (
+            new IncompatibleTypeException
+            (
+               operand.get_origin(),
+               operand_type,
+               previous_computed_type
+            )
+         );
+
+         computed_type =
+            (Type) previous_computed_type.generate_comparable_to(operand_type);
+
+         if (computed_type.equals(Type.ANY))
+         {
+            ErrorManager.handle
+            (
+               new IncomparableTypeException
+               (
+                  operand.get_origin(),
+                  operand_type,
+                  previous_computed_type
+               )
+            );
+         }
+      }
+
+      computed_type = operator.transform_type(computed_type);
+
+      return new Operation(origin, computed_type, operator, operands);
+   }
+
+   /**** Accessors ************************************************************/
+   public Operator get_operator ()
+   {
+      return operator;
+   }
+
+   public List<Computation> get_operands ()
+   {
+      return operands;
+   }
+
+   /**** Misc. ****************************************************************/
+   @Override
+   public String toString ()
+   {
+      final StringBuilder sb = new StringBuilder();
+
+      sb.append("(Operation ");
+      sb.append(operator.toString());
+
+      for (final Computation c: operands)
+      {
+         sb.append(" ");
+         sb.append(c.toString());
+      }
+
+      sb.append(")");
+
+      return sb.toString();
+   }
+}
diff --git a/src/core/src/tonkadur/fate/v1/lang/instruction/AddElement.java b/src/core/src/tonkadur/fate/v1/lang/instruction/AddElement.java
deleted file mode 100644
index 84828ca..0000000
--- a/src/core/src/tonkadur/fate/v1/lang/instruction/AddElement.java
+++ /dev/null
@@ -1,96 +0,0 @@
-package tonkadur.fate.v1.lang.instruction;
-
-import tonkadur.parser.Origin;
-import tonkadur.parser.ParsingError;
-
-import tonkadur.fate.v1.lang.meta.InstructionVisitor;
-import tonkadur.fate.v1.lang.meta.Instruction;
-import tonkadur.fate.v1.lang.meta.Computation;
-import tonkadur.fate.v1.lang.meta.Reference;
-import tonkadur.fate.v1.lang.meta.RecurrentChecks;
-
-public class AddElement extends Instruction
-{
-   /***************************************************************************/
-   /**** MEMBERS **************************************************************/
-   /***************************************************************************/
-   protected final Computation element;
-   protected final Reference collection;
-
-   /***************************************************************************/
-   /**** PROTECTED ************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   protected AddElement
-   (
-      final Origin origin,
-      final Computation element,
-      final Reference collection
-   )
-   {
-      super(origin);
-
-      this.collection = collection;
-      this.element = element;
-   }
-
-   /***************************************************************************/
-   /**** PUBLIC ***************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   public static AddElement build
-   (
-      final Origin origin,
-      final Computation element,
-      final Reference collection
-   )
-   throws ParsingError
-   {
-      RecurrentChecks.assert_is_a_collection_of(collection, element);
-
-      return new AddElement(origin, element, collection);
-   }
-
-   /**** Accessors ************************************************************/
-   @Override
-   public void get_visited_by (final InstructionVisitor iv)
-   throws Throwable
-   {
-      iv.visit_add_element(this);
-   }
-
-   public Reference get_collection ()
-   {
-      return collection;
-   }
-
-   public Computation get_element ()
-   {
-      return element;
-   }
-
-   /**** Misc. ****************************************************************/
-   @Override
-   public String toString ()
-   {
-      final StringBuilder sb = new StringBuilder();
-
-      sb.append("(AddElement");
-      sb.append(System.lineSeparator());
-      sb.append(System.lineSeparator());
-
-      sb.append("element:");
-      sb.append(System.lineSeparator());
-      sb.append(element.toString());
-      sb.append(System.lineSeparator());
-      sb.append(System.lineSeparator());
-
-      sb.append("collection:");
-      sb.append(System.lineSeparator());
-      sb.append(collection.toString());
-
-      sb.append(")");
-
-      return sb.toString();
-   }
-}
diff --git a/src/core/src/tonkadur/fate/v1/lang/instruction/AddElementAt.java b/src/core/src/tonkadur/fate/v1/lang/instruction/AddElementAt.java
deleted file mode 100644
index 56329ed..0000000
--- a/src/core/src/tonkadur/fate/v1/lang/instruction/AddElementAt.java
+++ /dev/null
@@ -1,114 +0,0 @@
-package tonkadur.fate.v1.lang.instruction;
-
-import tonkadur.parser.Origin;
-import tonkadur.parser.ParsingError;
-
-import tonkadur.fate.v1.lang.type.Type;
-
-import tonkadur.fate.v1.lang.meta.InstructionVisitor;
-import tonkadur.fate.v1.lang.meta.Instruction;
-import tonkadur.fate.v1.lang.meta.Computation;
-import tonkadur.fate.v1.lang.meta.Reference;
-import tonkadur.fate.v1.lang.meta.RecurrentChecks;
-
-public class AddElementAt extends Instruction
-{
-   /***************************************************************************/
-   /**** MEMBERS **************************************************************/
-   /***************************************************************************/
-   protected final Computation index;
-   protected final Computation element;
-   protected final Reference collection;
-
-   /***************************************************************************/
-   /**** PROTECTED ************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   protected AddElementAt
-   (
-      final Origin origin,
-      final Computation index,
-      final Computation element,
-      final Reference collection
-   )
-   {
-      super(origin);
-
-      this.index = index;
-      this.collection = collection;
-      this.element = element;
-   }
-
-   /***************************************************************************/
-   /**** PUBLIC ***************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   public static AddElementAt build
-   (
-      final Origin origin,
-      final Computation index,
-      final Computation element,
-      final Reference collection
-   )
-   throws ParsingError
-   {
-      RecurrentChecks.assert_is_a_list_of(collection, element);
-      RecurrentChecks.assert_can_be_used_as(index, Type.INT);
-
-      return new AddElementAt(origin, index, element, collection);
-   }
-
-   /**** Accessors ************************************************************/
-   @Override
-   public void get_visited_by (final InstructionVisitor iv)
-   throws Throwable
-   {
-      iv.visit_add_element_at(this);
-   }
-
-   public Reference get_collection ()
-   {
-      return collection;
-   }
-
-   public Computation get_index ()
-   {
-      return index;
-   }
-
-   public Computation get_element ()
-   {
-      return element;
-   }
-
-   /**** Misc. ****************************************************************/
-   @Override
-   public String toString ()
-   {
-      final StringBuilder sb = new StringBuilder();
-
-      sb.append("(AddElementAt");
-      sb.append(System.lineSeparator());
-      sb.append(System.lineSeparator());
-
-      sb.append("index:");
-      sb.append(System.lineSeparator());
-      sb.append(index.toString());
-      sb.append(System.lineSeparator());
-      sb.append(System.lineSeparator());
-
-      sb.append("element:");
-      sb.append(System.lineSeparator());
-      sb.append(element.toString());
-      sb.append(System.lineSeparator());
-      sb.append(System.lineSeparator());
-
-      sb.append("collection:");
-      sb.append(System.lineSeparator());
-      sb.append(collection.toString());
-
-      sb.append(")");
-
-      return sb.toString();
-   }
-}
diff --git a/src/core/src/tonkadur/fate/v1/lang/instruction/AddElementsOf.java b/src/core/src/tonkadur/fate/v1/lang/instruction/AddElementsOf.java
deleted file mode 100644
index f992c44..0000000
--- a/src/core/src/tonkadur/fate/v1/lang/instruction/AddElementsOf.java
+++ /dev/null
@@ -1,105 +0,0 @@
-package tonkadur.fate.v1.lang.instruction;
-
-import tonkadur.parser.Origin;
-import tonkadur.parser.ParsingError;
-
-import tonkadur.fate.v1.lang.type.CollectionType;
-
-import tonkadur.fate.v1.lang.meta.InstructionVisitor;
-import tonkadur.fate.v1.lang.meta.Instruction;
-import tonkadur.fate.v1.lang.meta.Reference;
-import tonkadur.fate.v1.lang.meta.Computation;
-import tonkadur.fate.v1.lang.meta.RecurrentChecks;
-
-public class AddElementsOf extends Instruction
-{
-   /***************************************************************************/
-   /**** MEMBERS **************************************************************/
-   /***************************************************************************/
-   protected final Computation other_collection;
-   protected final Reference collection;
-
-   /***************************************************************************/
-   /**** PROTECTED ************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   protected AddElementsOf
-   (
-      final Origin origin,
-      final Computation other_collection,
-      final Reference collection
-   )
-   {
-      super(origin);
-
-      this.collection = collection;
-      this.other_collection = other_collection;
-   }
-
-   /***************************************************************************/
-   /**** PUBLIC ***************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   public static AddElementsOf build
-   (
-      final Origin origin,
-      final Computation other_collection,
-      final Reference collection
-   )
-   throws ParsingError
-   {
-      RecurrentChecks.assert_is_a_collection(collection);
-      RecurrentChecks.assert_is_a_collection(other_collection);
-      RecurrentChecks.assert_can_be_used_as
-      (
-         other_collection.get_origin(),
-         ((CollectionType) other_collection.get_type()).get_content_type(),
-         ((CollectionType) collection.get_type()).get_content_type()
-      );
-
-      return new AddElementsOf(origin, other_collection, collection);
-   }
-
-   /**** Accessors ************************************************************/
-   @Override
-   public void get_visited_by (final InstructionVisitor iv)
-   throws Throwable
-   {
-      iv.visit_add_elements_of(this);
-   }
-
-   public Computation get_source_collection ()
-   {
-      return other_collection;
-   }
-
-   public Reference get_target_collection ()
-   {
-      return collection;
-   }
-
-   /**** Misc. ****************************************************************/
-   @Override
-   public String toString ()
-   {
-      final StringBuilder sb = new StringBuilder();
-
-      sb.append("(AddElementsOf");
-      sb.append(System.lineSeparator());
-      sb.append(System.lineSeparator());
-
-      sb.append("other_collection:");
-      sb.append(System.lineSeparator());
-      sb.append(other_collection.toString());
-      sb.append(System.lineSeparator());
-      sb.append(System.lineSeparator());
-
-      sb.append("collection:");
-      sb.append(System.lineSeparator());
-      sb.append(collection.toString());
-
-      sb.append(")");
-
-      return sb.toString();
-   }
-}
diff --git a/src/core/src/tonkadur/fate/v1/lang/instruction/ExtraInstructionInstance.java b/src/core/src/tonkadur/fate/v1/lang/instruction/ExtraInstructionInstance.java
index f13e05a..ecfa012 100644
--- a/src/core/src/tonkadur/fate/v1/lang/instruction/ExtraInstructionInstance.java
+++ b/src/core/src/tonkadur/fate/v1/lang/instruction/ExtraInstructionInstance.java
@@ -12,7 +12,7 @@ import tonkadur.fate.v1.lang.meta.InstructionVisitor;
 import tonkadur.fate.v1.lang.meta.ExtraInstruction;
 import tonkadur.fate.v1.lang.meta.RecurrentChecks;
 
-public class ExtraInstructionInstance extends Instruction
+public class ExtraInstructionInstance extends GenericInstruction
 {
    protected final ExtraInstruction instruction;
    protected final List<Computation> parameters;
@@ -28,7 +28,7 @@ public class ExtraInstructionInstance extends Instruction
       final List<Computation> parameters
    )
    {
-      super(origin);
+      super(origin, instruction.get_name());
 
       this.instruction = instruction;
       this.parameters = parameters;
diff --git a/src/core/src/tonkadur/fate/v1/lang/instruction/Filter.java b/src/core/src/tonkadur/fate/v1/lang/instruction/Filter.java
deleted file mode 100644
index d91f297..0000000
--- a/src/core/src/tonkadur/fate/v1/lang/instruction/Filter.java
+++ /dev/null
@@ -1,130 +0,0 @@
-package tonkadur.fate.v1.lang.instruction;
-
-import java.util.Collections;
-import java.util.List;
-import java.util.ArrayList;
-
-import tonkadur.parser.Origin;
-import tonkadur.parser.ParsingError;
-
-import tonkadur.fate.v1.lang.type.Type;
-import tonkadur.fate.v1.lang.type.LambdaType;
-import tonkadur.fate.v1.lang.type.CollectionType;
-
-import tonkadur.fate.v1.lang.meta.Computation;
-import tonkadur.fate.v1.lang.meta.Instruction;
-import tonkadur.fate.v1.lang.meta.InstructionVisitor;
-import tonkadur.fate.v1.lang.meta.Reference;
-import tonkadur.fate.v1.lang.meta.RecurrentChecks;
-
-public class Filter extends Instruction
-{
-   /***************************************************************************/
-   /**** MEMBERS **************************************************************/
-   /***************************************************************************/
-   protected final List<Computation> extra_params;
-   protected final Computation lambda_function;
-   protected final Reference collection;
-
-   /***************************************************************************/
-   /**** PROTECTED ************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   protected Filter
-   (
-      final Origin origin,
-      final Computation lambda_function,
-      final Reference collection,
-      final List<Computation> extra_params
-   )
-   {
-      super(origin);
-
-      this.lambda_function = lambda_function;
-      this.collection = collection;
-      this.extra_params = extra_params;
-   }
-
-   /***************************************************************************/
-   /**** PUBLIC ***************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   public static Filter build
-   (
-      final Origin origin,
-      final Computation lambda_function,
-      final Reference collection,
-      final List<Computation> extra_params
-   )
-   throws ParsingError
-   {
-      final List<Type> target_signature;
-
-      target_signature = new ArrayList<Type>();
-
-      RecurrentChecks.assert_is_a_collection(collection);
-
-      target_signature.add
-      (
-         ((CollectionType) collection.get_type()).get_content_type()
-      );
-
-      for (final Computation c: extra_params)
-      {
-         target_signature.add(c.get_type());
-      }
-      RecurrentChecks.assert_lambda_matches_types
-      (
-         lambda_function,
-         Type.BOOL,
-         target_signature
-      );
-
-      return new Filter(origin, lambda_function, collection, extra_params);
-   }
-
-   /**** Accessors ************************************************************/
-   @Override
-   public void get_visited_by (final InstructionVisitor iv)
-   throws Throwable
-   {
-      iv.visit_filter(this);
-   }
-
-   public Computation get_lambda_function ()
-   {
-      return lambda_function;
-   }
-
-   public Reference get_collection ()
-   {
-      return collection;
-   }
-
-   public List<Computation> get_extra_parameters ()
-   {
-      return extra_params;
-   }
-
-   /**** Misc. ****************************************************************/
-   @Override
-   public String toString ()
-   {
-      final StringBuilder sb = new StringBuilder();
-
-      sb.append("(Filter ");
-      sb.append(lambda_function.toString());
-      sb.append(" ");
-      sb.append(collection.toString());
-
-      for (final Computation c: extra_params)
-      {
-         sb.append(" ");
-         sb.append(c.toString());
-      }
-
-      sb.append(")");
-
-      return sb.toString();
-   }
-}
diff --git a/src/core/src/tonkadur/fate/v1/lang/instruction/Free.java b/src/core/src/tonkadur/fate/v1/lang/instruction/Free.java
deleted file mode 100644
index 65e6e6f..0000000
--- a/src/core/src/tonkadur/fate/v1/lang/instruction/Free.java
+++ /dev/null
@@ -1,62 +0,0 @@
-package tonkadur.fate.v1.lang.instruction;
-
-import tonkadur.error.ErrorManager;
-
-import tonkadur.parser.Origin;
-
-import tonkadur.fate.v1.lang.type.Type;
-
-import tonkadur.fate.v1.lang.meta.InstructionVisitor;
-import tonkadur.fate.v1.lang.meta.Instruction;
-import tonkadur.fate.v1.lang.meta.Reference;
-
-public class Free extends Instruction
-{
-   /***************************************************************************/
-   /**** MEMBERS **************************************************************/
-   /***************************************************************************/
-   protected final Reference value_reference;
-
-   /***************************************************************************/
-   /**** PROTECTED ************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-
-   /***************************************************************************/
-   /**** PUBLIC ***************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   public Free (final Origin origin, final Reference value_reference)
-   {
-      super(origin);
-
-      this.value_reference = value_reference;
-   }
-
-   /**** Accessors ************************************************************/
-   @Override
-   public void get_visited_by (final InstructionVisitor iv)
-   throws Throwable
-   {
-      iv.visit_free(this);
-   }
-
-   public Reference get_reference ()
-   {
-      return value_reference;
-   }
-
-   /**** Misc. ****************************************************************/
-   @Override
-   public String toString ()
-   {
-      final StringBuilder sb = new StringBuilder();
-
-      sb.append("(Free ");
-      sb.append(value_reference.toString());
-
-      sb.append(")");
-
-      return sb.toString();
-   }
-}
diff --git a/src/core/src/tonkadur/fate/v1/lang/instruction/GenericInstruction.java b/src/core/src/tonkadur/fate/v1/lang/instruction/GenericInstruction.java
new file mode 100644
index 0000000..0035ac0
--- /dev/null
+++ b/src/core/src/tonkadur/fate/v1/lang/instruction/GenericInstruction.java
@@ -0,0 +1,160 @@
+package tonkadur.fate.v1.lang.instruction;
+
+import java.util.Collection;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+import tonkadur.parser.Origin;
+
+import tonkadur.functional.Cons;
+
+import tonkadur.fate.v1.lang.type.Type;
+
+import tonkadur.fate.v1.lang.meta.InstructionVisitor;
+import tonkadur.fate.v1.lang.meta.Instruction;
+import tonkadur.fate.v1.lang.meta.Computation;
+
+public class GenericInstruction extends Instruction
+{
+   /***************************************************************************/
+   /**** STATIC ***************************************************************/
+   /***************************************************************************/
+   protected static final Map<String, Cons<GenericInstruction, Object>>
+      REGISTERED;
+
+   static
+   {
+      REGISTERED = new HashMap<String, Cons<GenericInstruction, Object>>();
+   }
+
+   public static GenericInstruction build
+   (
+      final Origin origin,
+      final String name,
+      final List<Computation> call_parameters
+   )
+   throws Throwable
+   {
+      final Cons<GenericInstruction, Object> target;
+
+      target = REGISTERED.get(name);
+
+      if (target == null)
+      {
+         // TODO Exception handling.
+      }
+
+      return target.get_car().build(origin, call_parameters, target.get_cdr());
+   }
+
+   /***************************************************************************/
+   /**** MEMBERS **************************************************************/
+   /***************************************************************************/
+   protected final String name;
+
+   /***************************************************************************/
+   /**** PROTECTED ************************************************************/
+   /***************************************************************************/
+   /**** Constructors *********************************************************/
+   protected GenericInstruction
+   (
+      final Origin origin,
+      final String name
+   )
+   {
+      super(origin);
+
+      this.name = name;
+   }
+
+   protected GenericInstruction build
+   (
+      final Origin origin,
+      final List<Computation> call_parameters,
+      final Object constructor_parameter
+   )
+   throws Throwable
+   {
+      throw
+         new Exception
+         (
+            "Missing build function for GenericInstruction '"
+            + name
+            + "'."
+         );
+   }
+
+   protected void register
+   (
+      final String name,
+      final Object constructor_parameter
+   )
+   throws Exception
+   {
+      if (REGISTERED.containsKey(name))
+      {
+         // TODO Exception handling.
+         new Exception
+         (
+            "There already is a GenericInstruction with the name '"
+            + name
+            + "'."
+         );
+
+         return;
+      }
+
+      REGISTERED.put(name, new Cons(this, constructor_parameter));
+   }
+
+   protected void register (final Object constructor_parameter)
+   throws Exception
+   {
+      register(get_name(), constructor_parameter);
+   }
+
+   protected void register
+   (
+      final Collection<String> names,
+      final Object constructor_parameter
+   )
+   throws Exception
+   {
+      for (final String name: names)
+      {
+         register(name, constructor_parameter);
+      }
+   }
+
+   /***************************************************************************/
+   /**** PUBLIC ***************************************************************/
+   /***************************************************************************/
+   /**** Constructors *********************************************************/
+
+   /**** Accessors ************************************************************/
+   @Override
+   public void get_visited_by (final InstructionVisitor cv)
+   throws Throwable
+   {
+      cv.visit_generic_instruction(this);
+   }
+
+   public String get_name ()
+   {
+      return name;
+   }
+
+   /**** Misc. ****************************************************************/
+   @Override
+   public String toString ()
+   {
+      final StringBuilder sb = new StringBuilder();
+
+      sb.append("(GenericInstruction ");
+      sb.append(get_name());
+      sb.append(")");
+
+      return sb.toString();
+   }
+}
diff --git a/src/core/src/tonkadur/fate/v1/lang/instruction/IndexedFilter.java b/src/core/src/tonkadur/fate/v1/lang/instruction/IndexedFilter.java
deleted file mode 100644
index 6e3da57..0000000
--- a/src/core/src/tonkadur/fate/v1/lang/instruction/IndexedFilter.java
+++ /dev/null
@@ -1,132 +0,0 @@
-package tonkadur.fate.v1.lang.instruction;
-
-import java.util.Collections;
-import java.util.List;
-import java.util.ArrayList;
-
-import tonkadur.parser.Origin;
-import tonkadur.parser.ParsingError;
-
-import tonkadur.fate.v1.lang.type.Type;
-import tonkadur.fate.v1.lang.type.LambdaType;
-import tonkadur.fate.v1.lang.type.CollectionType;
-
-import tonkadur.fate.v1.lang.meta.Computation;
-import tonkadur.fate.v1.lang.meta.Instruction;
-import tonkadur.fate.v1.lang.meta.InstructionVisitor;
-import tonkadur.fate.v1.lang.meta.Reference;
-import tonkadur.fate.v1.lang.meta.RecurrentChecks;
-
-public class IndexedFilter extends Instruction
-{
-   /***************************************************************************/
-   /**** MEMBERS **************************************************************/
-   /***************************************************************************/
-   protected final List<Computation> extra_params;
-   protected final Computation lambda_function;
-   protected final Reference collection;
-
-   /***************************************************************************/
-   /**** PROTECTED ************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   protected IndexedFilter
-   (
-      final Origin origin,
-      final Computation lambda_function,
-      final Reference collection,
-      final List<Computation> extra_params
-   )
-   {
-      super(origin);
-
-      this.lambda_function = lambda_function;
-      this.collection = collection;
-      this.extra_params = extra_params;
-   }
-
-   /***************************************************************************/
-   /**** PUBLIC ***************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   public static IndexedFilter build
-   (
-      final Origin origin,
-      final Computation lambda_function,
-      final Reference collection,
-      final List<Computation> extra_params
-   )
-   throws ParsingError
-   {
-      final List<Type> target_signature;
-
-      target_signature = new ArrayList<Type>();
-
-      RecurrentChecks.assert_is_a_collection(collection);
-
-      target_signature.add(Type.INT);
-      target_signature.add
-      (
-         ((CollectionType) collection.get_type()).get_content_type()
-      );
-
-      for (final Computation c: extra_params)
-      {
-         target_signature.add(c.get_type());
-      }
-
-      RecurrentChecks.assert_lambda_matches_types
-      (
-         lambda_function,
-         Type.BOOL,
-         target_signature
-      );
-
-      return new IndexedFilter(origin, lambda_function, collection, extra_params);
-   }
-
-   /**** Accessors ************************************************************/
-   @Override
-   public void get_visited_by (final InstructionVisitor iv)
-   throws Throwable
-   {
-      iv.visit_indexed_filter(this);
-   }
-
-   public Computation get_lambda_function ()
-   {
-      return lambda_function;
-   }
-
-   public Reference get_collection ()
-   {
-      return collection;
-   }
-
-   public List<Computation> get_extra_parameters ()
-   {
-      return extra_params;
-   }
-
-   /**** Misc. ****************************************************************/
-   @Override
-   public String toString ()
-   {
-      final StringBuilder sb = new StringBuilder();
-
-      sb.append("(IndexedFilter ");
-      sb.append(lambda_function.toString());
-      sb.append(" ");
-      sb.append(collection.toString());
-
-      for (final Computation c: extra_params)
-      {
-         sb.append(" ");
-         sb.append(c.toString());
-      }
-
-      sb.append(")");
-
-      return sb.toString();
-   }
-}
diff --git a/src/core/src/tonkadur/fate/v1/lang/instruction/IndexedMap.java b/src/core/src/tonkadur/fate/v1/lang/instruction/IndexedMap.java
deleted file mode 100644
index e603332..0000000
--- a/src/core/src/tonkadur/fate/v1/lang/instruction/IndexedMap.java
+++ /dev/null
@@ -1,130 +0,0 @@
-package tonkadur.fate.v1.lang.instruction;
-
-import java.util.ArrayList;
-import java.util.List;
-
-import tonkadur.parser.Origin;
-import tonkadur.parser.ParsingError;
-
-import tonkadur.fate.v1.lang.type.Type;
-import tonkadur.fate.v1.lang.type.CollectionType;
-
-import tonkadur.fate.v1.lang.meta.Computation;
-import tonkadur.fate.v1.lang.meta.Instruction;
-import tonkadur.fate.v1.lang.meta.InstructionVisitor;
-import tonkadur.fate.v1.lang.meta.Reference;
-import tonkadur.fate.v1.lang.meta.RecurrentChecks;
-
-public class IndexedMap extends Instruction
-{
-   /***************************************************************************/
-   /**** MEMBERS **************************************************************/
-   /***************************************************************************/
-   protected final List<Computation> extra_params;
-   protected final Computation lambda_function;
-   protected final Reference collection;
-
-   /***************************************************************************/
-   /**** PROTECTED ************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   protected IndexedMap
-   (
-      final Origin origin,
-      final Computation lambda_function,
-      final Reference collection,
-      final List<Computation> extra_params
-   )
-   {
-      super(origin);
-
-      this.lambda_function = lambda_function;
-      this.collection = collection;
-      this.extra_params = extra_params;
-   }
-
-   /***************************************************************************/
-   /**** PUBLIC ***************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   public static IndexedMap build
-   (
-      final Origin origin,
-      final Computation lambda_function,
-      final Reference collection,
-      final List<Computation> extra_params
-   )
-   throws Throwable
-   {
-      final List<Type> in_types;
-
-      in_types = new ArrayList<Type>();
-
-      RecurrentChecks.assert_is_a_collection(collection);
-
-      in_types.add(Type.INT);
-      in_types.add
-      (
-         ((CollectionType) collection.get_type()).get_content_type()
-      );
-
-      for (final Computation c: extra_params)
-      {
-         in_types.add(c.get_type());
-      }
-
-      RecurrentChecks.assert_lambda_matches_types
-      (
-         lambda_function,
-         ((CollectionType) collection.get_type()).get_content_type(),
-         in_types
-      );
-
-      return new IndexedMap(origin, lambda_function, collection, extra_params);
-   }
-
-   /**** Accessors ************************************************************/
-   @Override
-   public void get_visited_by (final InstructionVisitor iv)
-   throws Throwable
-   {
-      iv.visit_indexed_map(this);
-   }
-
-   public Computation get_lambda_function ()
-   {
-      return lambda_function;
-   }
-
-   public Reference get_collection ()
-   {
-      return collection;
-   }
-
-   public List<Computation> get_extra_parameters ()
-   {
-      return extra_params;
-   }
-
-   /**** Misc. ****************************************************************/
-   @Override
-   public String toString ()
-   {
-      final StringBuilder sb = new StringBuilder();
-
-      sb.append("(IndexedMap ");
-      sb.append(lambda_function.toString());
-      sb.append(" ");
-      sb.append(collection.toString());
-
-      for (final Computation c: extra_params)
-      {
-         sb.append(" ");
-         sb.append(c.toString());
-      }
-
-      sb.append(")");
-
-      return sb.toString();
-   }
-}
diff --git a/src/core/src/tonkadur/fate/v1/lang/instruction/IndexedMerge.java b/src/core/src/tonkadur/fate/v1/lang/instruction/IndexedMerge.java
deleted file mode 100644
index 060438c..0000000
--- a/src/core/src/tonkadur/fate/v1/lang/instruction/IndexedMerge.java
+++ /dev/null
@@ -1,216 +0,0 @@
-package tonkadur.fate.v1.lang.instruction;
-
-import java.util.ArrayList;
-import java.util.List;
-
-import tonkadur.parser.Origin;
-import tonkadur.parser.ParsingError;
-
-import tonkadur.fate.v1.lang.type.Type;
-import tonkadur.fate.v1.lang.type.CollectionType;
-
-import tonkadur.fate.v1.lang.meta.Computation;
-import tonkadur.fate.v1.lang.meta.Instruction;
-import tonkadur.fate.v1.lang.meta.InstructionVisitor;
-import tonkadur.fate.v1.lang.meta.Reference;
-import tonkadur.fate.v1.lang.meta.RecurrentChecks;
-
-public class IndexedMerge extends Instruction
-{
-   /***************************************************************************/
-   /**** MEMBERS **************************************************************/
-   /***************************************************************************/
-   protected final List<Computation> extra_params;
-   protected final Computation lambda_function;
-   protected final Reference collection;
-   protected final Computation default_a;
-   protected final Computation collection_in_b;
-   protected final Computation default_b;
-
-   /***************************************************************************/
-   /**** PROTECTED ************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   protected IndexedMerge
-   (
-      final Origin origin,
-      final Computation lambda_function,
-      final Computation collection_in_b,
-      final Computation default_b,
-      final Reference collection,
-      final Computation default_a,
-      final List<Computation> extra_params
-   )
-   {
-      super(origin);
-
-      this.lambda_function = lambda_function;
-      this.collection = collection;
-      this.default_a = default_a;
-      this.collection_in_b = collection_in_b;
-      this.default_b = default_b;
-      this.extra_params = extra_params;
-   }
-
-   /***************************************************************************/
-   /**** PUBLIC ***************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   public static IndexedMerge build
-   (
-      final Origin origin,
-      final Computation lambda_function,
-      final Computation collection_in_b,
-      final Computation default_b,
-      final Reference collection,
-      final Computation default_a,
-      final List<Computation> extra_params
-   )
-   throws Throwable
-   {
-      final List<Type> types_in;
-
-      types_in = new ArrayList<Type>();
-
-      if (default_a == null)
-      {
-         RecurrentChecks.assert_is_a_collection(collection);
-      }
-      else
-      {
-         RecurrentChecks.assert_is_a_collection_of(collection, default_a);
-      }
-
-      if (default_b == null)
-      {
-         RecurrentChecks.assert_is_a_collection(collection_in_b);
-      }
-      else
-      {
-         RecurrentChecks.assert_is_a_collection_of(collection_in_b, default_b);
-      }
-
-      types_in.add(Type.INT);
-      types_in.add
-      (
-         ((CollectionType) collection.get_type()).get_content_type()
-      );
-
-      if (default_b != null)
-      {
-         types_in.add(Type.INT);
-      }
-
-      types_in.add
-      (
-         ((CollectionType) collection_in_b.get_type()).get_content_type()
-      );
-
-      for (final Computation c: extra_params)
-      {
-         types_in.add(c.get_type());
-      }
-
-      RecurrentChecks.assert_lambda_matches_types
-      (
-         lambda_function,
-         ((CollectionType) collection.get_type()).get_content_type(),
-         types_in
-      );
-
-      return
-         new IndexedMerge
-         (
-            origin,
-            lambda_function,
-            collection_in_b,
-            default_b,
-            collection,
-            default_a,
-            extra_params
-         );
-   }
-
-   /**** Accessors ************************************************************/
-   @Override
-   public void get_visited_by (final InstructionVisitor iv)
-   throws Throwable
-   {
-      iv.visit_indexed_merge(this);
-   }
-
-   public Computation get_lambda_function ()
-   {
-      return lambda_function;
-   }
-
-   public Computation get_main_default ()
-   {
-      return default_a;
-   }
-
-   public Computation get_secondary_collection ()
-   {
-      return collection_in_b;
-   }
-
-   public Computation get_secondary_default ()
-   {
-      return default_b;
-   }
-
-   public Reference get_main_collection ()
-   {
-      return collection;
-   }
-
-   public List<Computation> get_extra_parameters ()
-   {
-      return extra_params;
-   }
-
-   /**** Misc. ****************************************************************/
-   @Override
-   public String toString ()
-   {
-      final StringBuilder sb = new StringBuilder();
-
-      sb.append("(IndexedMerge ");
-      sb.append(lambda_function.toString());
-      sb.append(" ");
-      sb.append(collection.toString());
-      sb.append(" ");
-
-      if (default_a == null)
-      {
-         sb.append("null");
-      }
-      else
-      {
-         sb.append(default_a.toString());
-      }
-
-      sb.append(" ");
-      sb.append(collection_in_b.toString());
-      sb.append(" ");
-
-      if (default_b == null)
-      {
-         sb.append("null");
-      }
-      else
-      {
-         sb.append(default_b.toString());
-      }
-
-      for (final Computation c: extra_params)
-      {
-         sb.append(" ");
-         sb.append(c.toString());
-      }
-
-      sb.append(")");
-
-      return sb.toString();
-   }
-}
diff --git a/src/core/src/tonkadur/fate/v1/lang/instruction/IndexedPartition.java b/src/core/src/tonkadur/fate/v1/lang/instruction/IndexedPartition.java
deleted file mode 100644
index cec125a..0000000
--- a/src/core/src/tonkadur/fate/v1/lang/instruction/IndexedPartition.java
+++ /dev/null
@@ -1,156 +0,0 @@
-package tonkadur.fate.v1.lang.instruction;
-
-import java.util.Collections;
-import java.util.List;
-import java.util.ArrayList;
-
-import tonkadur.parser.Origin;
-import tonkadur.parser.ParsingError;
-
-import tonkadur.fate.v1.lang.type.Type;
-import tonkadur.fate.v1.lang.type.CollectionType;
-
-import tonkadur.fate.v1.lang.meta.Computation;
-import tonkadur.fate.v1.lang.meta.Instruction;
-import tonkadur.fate.v1.lang.meta.InstructionVisitor;
-import tonkadur.fate.v1.lang.meta.Reference;
-import tonkadur.fate.v1.lang.meta.RecurrentChecks;
-
-public class IndexedPartition extends Instruction
-{
-   /***************************************************************************/
-   /**** MEMBERS **************************************************************/
-   /***************************************************************************/
-   protected final List<Computation> extra_params;
-   protected final Computation lambda_function;
-   protected final Reference collection_in;
-   protected final Reference collection_out;
-
-   /***************************************************************************/
-   /**** PROTECTED ************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   protected IndexedPartition
-   (
-      final Origin origin,
-      final Computation lambda_function,
-      final Reference collection_in,
-      final Reference collection_out,
-      final List<Computation> extra_params
-   )
-   {
-      super(origin);
-
-      this.lambda_function = lambda_function;
-      this.collection_in = collection_in;
-      this.collection_out = collection_out;
-      this.extra_params = extra_params;
-   }
-
-   /***************************************************************************/
-   /**** PUBLIC ***************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   public static IndexedPartition build
-   (
-      final Origin origin,
-      final Computation lambda_function,
-      final Reference collection_in,
-      final Reference collection_out,
-      final List<Computation> extra_params
-   )
-   throws ParsingError
-   {
-      final List<Type> target_signature;
-
-      target_signature = new ArrayList<Type>();
-
-      RecurrentChecks.assert_is_a_collection(collection_in);
-      RecurrentChecks.assert_is_a_collection(collection_out);
-      RecurrentChecks.assert_can_be_used_as
-      (
-         collection_in,
-         collection_out.get_type()
-      );
-
-      target_signature.add(Type.INT);
-      target_signature.add
-      (
-         ((CollectionType) collection_in.get_type()).get_content_type()
-      );
-
-      for (final Computation c: extra_params)
-      {
-         target_signature.add(c.get_type());
-      }
-
-      RecurrentChecks.assert_lambda_matches_types
-      (
-         lambda_function,
-         Type.BOOL,
-         target_signature
-      );
-
-      return
-         new IndexedPartition
-         (
-            origin,
-            lambda_function,
-            collection_in,
-            collection_out,
-            extra_params
-         );
-   }
-
-   /**** Accessors ************************************************************/
-   @Override
-   public void get_visited_by (final InstructionVisitor iv)
-   throws Throwable
-   {
-      iv.visit_indexed_partition(this);
-   }
-
-   public Computation get_lambda_function ()
-   {
-      return lambda_function;
-   }
-
-   public Reference get_collection_in ()
-   {
-      return collection_in;
-   }
-
-   public Reference get_collection_out ()
-   {
-      return collection_out;
-   }
-
-   public List<Computation> get_extra_parameters ()
-   {
-      return extra_params;
-   }
-
-   /**** Misc. ****************************************************************/
-   @Override
-   public String toString ()
-   {
-      final StringBuilder sb = new StringBuilder();
-
-      sb.append("(IndexedPartition ");
-      sb.append(lambda_function.toString());
-      sb.append(" ");
-      sb.append(collection_in.toString());
-      sb.append(" ");
-      sb.append(collection_out.toString());
-
-      for (final Computation c: extra_params)
-      {
-         sb.append(" ");
-         sb.append(c.toString());
-      }
-
-      sb.append(")");
-
-      return sb.toString();
-   }
-}
diff --git a/src/core/src/tonkadur/fate/v1/lang/instruction/Map.java b/src/core/src/tonkadur/fate/v1/lang/instruction/Map.java
deleted file mode 100644
index 1bcb1e4..0000000
--- a/src/core/src/tonkadur/fate/v1/lang/instruction/Map.java
+++ /dev/null
@@ -1,130 +0,0 @@
-package tonkadur.fate.v1.lang.instruction;
-
-import java.util.Collections;
-import java.util.List;
-import java.util.ArrayList;
-
-import tonkadur.parser.Origin;
-import tonkadur.parser.ParsingError;
-
-import tonkadur.fate.v1.lang.type.Type;
-import tonkadur.fate.v1.lang.type.CollectionType;
-
-import tonkadur.fate.v1.lang.meta.Computation;
-import tonkadur.fate.v1.lang.meta.Instruction;
-import tonkadur.fate.v1.lang.meta.InstructionVisitor;
-import tonkadur.fate.v1.lang.meta.Reference;
-import tonkadur.fate.v1.lang.meta.RecurrentChecks;
-
-public class Map extends Instruction
-{
-   /***************************************************************************/
-   /**** MEMBERS **************************************************************/
-   /***************************************************************************/
-   protected final List<Computation> extra_params;
-   protected final Computation lambda_function;
-   protected final Reference collection;
-
-   /***************************************************************************/
-   /**** PROTECTED ************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   protected Map
-   (
-      final Origin origin,
-      final Computation lambda_function,
-      final Reference collection,
-      final List<Computation> extra_params
-   )
-   {
-      super(origin);
-
-      this.lambda_function = lambda_function;
-      this.collection = collection;
-      this.extra_params = extra_params;
-   }
-
-   /***************************************************************************/
-   /**** PUBLIC ***************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   public static Map build
-   (
-      final Origin origin,
-      final Computation lambda_function,
-      final Reference collection,
-      final List<Computation> extra_params
-   )
-   throws ParsingError
-   {
-      final List<Type> target_signature;
-
-      target_signature = new ArrayList<Type>();
-
-      RecurrentChecks.assert_is_a_collection(collection);
-
-      target_signature.add
-      (
-         ((CollectionType) collection.get_type()).get_content_type()
-      );
-
-      for (final Computation c: extra_params)
-      {
-         target_signature.add(c.get_type());
-      }
-
-      RecurrentChecks.assert_lambda_matches_types
-      (
-         lambda_function,
-         ((CollectionType) collection.get_type()).get_content_type(),
-         target_signature
-      );
-
-      return new Map(origin, lambda_function, collection, extra_params);
-   }
-
-   /**** Accessors ************************************************************/
-   @Override
-   public void get_visited_by (final InstructionVisitor iv)
-   throws Throwable
-   {
-      iv.visit_map(this);
-   }
-
-   public Computation get_lambda_function ()
-   {
-      return lambda_function;
-   }
-
-   public Reference get_collection ()
-   {
-      return collection;
-   }
-
-   public List<Computation> get_extra_parameters ()
-   {
-      return extra_params;
-   }
-
-   /**** Misc. ****************************************************************/
-   @Override
-   public String toString ()
-   {
-      final StringBuilder sb = new StringBuilder();
-
-      sb.append("(Map ");
-      sb.append(lambda_function.toString());
-      sb.append(" ");
-      sb.append(collection.toString());
-
-      for (final Computation c: extra_params)
-      {
-         sb.append(" ");
-         sb.append(c.toString());
-      }
-
-      sb.append(")");
-
-      return sb.toString();
-   }
-}
diff --git a/src/core/src/tonkadur/fate/v1/lang/instruction/Merge.java b/src/core/src/tonkadur/fate/v1/lang/instruction/Merge.java
deleted file mode 100644
index 9a40f2f..0000000
--- a/src/core/src/tonkadur/fate/v1/lang/instruction/Merge.java
+++ /dev/null
@@ -1,210 +0,0 @@
-package tonkadur.fate.v1.lang.instruction;
-
-import java.util.ArrayList;
-import java.util.List;
-
-import tonkadur.parser.Origin;
-import tonkadur.parser.ParsingError;
-
-import tonkadur.fate.v1.lang.type.Type;
-import tonkadur.fate.v1.lang.type.CollectionType;
-
-import tonkadur.fate.v1.lang.meta.Computation;
-import tonkadur.fate.v1.lang.meta.Instruction;
-import tonkadur.fate.v1.lang.meta.InstructionVisitor;
-import tonkadur.fate.v1.lang.meta.Reference;
-import tonkadur.fate.v1.lang.meta.RecurrentChecks;
-
-public class Merge extends Instruction
-{
-   /***************************************************************************/
-   /**** MEMBERS **************************************************************/
-   /***************************************************************************/
-   protected final List<Computation> extra_params;
-   protected final Computation lambda_function;
-   protected final Reference collection;
-   protected final Computation default_a;
-   protected final Computation collection_in_b;
-   protected final Computation default_b;
-
-   /***************************************************************************/
-   /**** PROTECTED ************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   protected Merge
-   (
-      final Origin origin,
-      final Computation lambda_function,
-      final Computation collection_in_b,
-      final Computation default_b,
-      final Reference collection,
-      final Computation default_a,
-      final List<Computation> extra_params
-   )
-   {
-      super(origin);
-
-      this.lambda_function = lambda_function;
-      this.collection = collection;
-      this.default_a = default_a;
-      this.collection_in_b = collection_in_b;
-      this.default_b = default_b;
-      this.extra_params = extra_params;
-   }
-
-   /***************************************************************************/
-   /**** PUBLIC ***************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   public static Merge build
-   (
-      final Origin origin,
-      final Computation lambda_function,
-      final Computation collection_in_b,
-      final Computation default_b,
-      final Reference collection,
-      final Computation default_a,
-      final List<Computation> extra_params
-   )
-   throws Throwable
-   {
-      final List<Type> types_in;
-
-      types_in = new ArrayList<Type>();
-
-      if (default_a == null)
-      {
-         RecurrentChecks.assert_is_a_collection(collection);
-      }
-      else
-      {
-         RecurrentChecks.assert_is_a_collection_of(collection, default_a);
-      }
-
-      if (default_b == null)
-      {
-         RecurrentChecks.assert_is_a_collection(collection_in_b);
-      }
-      else
-      {
-         RecurrentChecks.assert_is_a_collection_of(collection_in_b, default_b);
-      }
-
-      types_in.add
-      (
-         ((CollectionType) collection.get_type()).get_content_type()
-      );
-
-      types_in.add
-      (
-         ((CollectionType) collection_in_b.get_type()).get_content_type()
-      );
-
-      for (final Computation c: extra_params)
-      {
-         types_in.add(c.get_type());
-      }
-
-      RecurrentChecks.assert_lambda_matches_types
-      (
-         lambda_function,
-         ((CollectionType) collection.get_type()).get_content_type(),
-         types_in
-      );
-
-      return
-         new Merge
-         (
-            origin,
-            lambda_function,
-            collection_in_b,
-            default_b,
-            collection,
-            default_a,
-            extra_params
-         );
-   }
-
-   /**** Accessors ************************************************************/
-   @Override
-   public void get_visited_by (final InstructionVisitor iv)
-   throws Throwable
-   {
-      iv.visit_merge(this);
-   }
-
-   public Computation get_lambda_function ()
-   {
-      return lambda_function;
-   }
-
-   public Computation get_main_default ()
-   {
-      return default_a;
-   }
-
-   public Computation get_secondary_collection ()
-   {
-      return collection_in_b;
-   }
-
-   public Computation get_secondary_default ()
-   {
-      return default_b;
-   }
-
-   public Reference get_main_collection ()
-   {
-      return collection;
-   }
-
-   public List<Computation> get_extra_parameters ()
-   {
-      return extra_params;
-   }
-
-   /**** Misc. ****************************************************************/
-   @Override
-   public String toString ()
-   {
-      final StringBuilder sb = new StringBuilder();
-
-      sb.append("(Merge ");
-      sb.append(lambda_function.toString());
-      sb.append(" ");
-      sb.append(collection.toString());
-      sb.append(" ");
-
-      if (default_a == null)
-      {
-         sb.append("null");
-      }
-      else
-      {
-         sb.append(default_a.toString());
-      }
-
-      sb.append(" ");
-      sb.append(collection_in_b.toString());
-      sb.append(" ");
-
-      if (default_b == null)
-      {
-         sb.append("null");
-      }
-      else
-      {
-         sb.append(default_b.toString());
-      }
-
-      for (final Computation c: extra_params)
-      {
-         sb.append(" ");
-         sb.append(c.toString());
-      }
-
-      sb.append(")");
-
-      return sb.toString();
-   }
-}
diff --git a/src/core/src/tonkadur/fate/v1/lang/instruction/Partition.java b/src/core/src/tonkadur/fate/v1/lang/instruction/Partition.java
deleted file mode 100644
index 33cb152..0000000
--- a/src/core/src/tonkadur/fate/v1/lang/instruction/Partition.java
+++ /dev/null
@@ -1,155 +0,0 @@
-package tonkadur.fate.v1.lang.instruction;
-
-import java.util.Collections;
-import java.util.List;
-import java.util.ArrayList;
-
-import tonkadur.parser.Origin;
-import tonkadur.parser.ParsingError;
-
-import tonkadur.fate.v1.lang.type.Type;
-import tonkadur.fate.v1.lang.type.CollectionType;
-
-import tonkadur.fate.v1.lang.meta.Computation;
-import tonkadur.fate.v1.lang.meta.Instruction;
-import tonkadur.fate.v1.lang.meta.InstructionVisitor;
-import tonkadur.fate.v1.lang.meta.Reference;
-import tonkadur.fate.v1.lang.meta.RecurrentChecks;
-
-public class Partition extends Instruction
-{
-   /***************************************************************************/
-   /**** MEMBERS **************************************************************/
-   /***************************************************************************/
-   protected final List<Computation> extra_params;
-   protected final Computation lambda_function;
-   protected final Reference collection_in;
-   protected final Reference collection_out;
-
-   /***************************************************************************/
-   /**** PROTECTED ************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   protected Partition
-   (
-      final Origin origin,
-      final Computation lambda_function,
-      final Reference collection_in,
-      final Reference collection_out,
-      final List<Computation> extra_params
-   )
-   {
-      super(origin);
-
-      this.lambda_function = lambda_function;
-      this.collection_in = collection_in;
-      this.collection_out = collection_out;
-      this.extra_params = extra_params;
-   }
-
-   /***************************************************************************/
-   /**** PUBLIC ***************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   public static Partition build
-   (
-      final Origin origin,
-      final Computation lambda_function,
-      final Reference collection_in,
-      final Reference collection_out,
-      final List<Computation> extra_params
-   )
-   throws ParsingError
-   {
-      final List<Type> target_signature;
-
-      target_signature = new ArrayList<Type>();
-
-      RecurrentChecks.assert_is_a_collection(collection_in);
-      RecurrentChecks.assert_is_a_collection(collection_out);
-      RecurrentChecks.assert_can_be_used_as
-      (
-         collection_in,
-         collection_out.get_type()
-      );
-
-      target_signature.add
-      (
-         ((CollectionType) collection_in.get_type()).get_content_type()
-      );
-
-      for (final Computation c: extra_params)
-      {
-         target_signature.add(c.get_type());
-      }
-
-      RecurrentChecks.assert_lambda_matches_types
-      (
-         lambda_function,
-         Type.BOOL,
-         target_signature
-      );
-
-      return
-         new Partition
-         (
-            origin,
-            lambda_function,
-            collection_in,
-            collection_out,
-            extra_params
-         );
-   }
-
-   /**** Accessors ************************************************************/
-   @Override
-   public void get_visited_by (final InstructionVisitor iv)
-   throws Throwable
-   {
-      iv.visit_partition(this);
-   }
-
-   public Computation get_lambda_function ()
-   {
-      return lambda_function;
-   }
-
-   public Reference get_collection_in ()
-   {
-      return collection_in;
-   }
-
-   public Reference get_collection_out ()
-   {
-      return collection_out;
-   }
-
-   public List<Computation> get_extra_parameters ()
-   {
-      return extra_params;
-   }
-
-   /**** Misc. ****************************************************************/
-   @Override
-   public String toString ()
-   {
-      final StringBuilder sb = new StringBuilder();
-
-      sb.append("(Partition ");
-      sb.append(lambda_function.toString());
-      sb.append(" ");
-      sb.append(collection_in.toString());
-      sb.append(" ");
-      sb.append(collection_out.toString());
-
-      for (final Computation c: extra_params)
-      {
-         sb.append(" ");
-         sb.append(c.toString());
-      }
-
-      sb.append(")");
-
-      return sb.toString();
-   }
-}
diff --git a/src/core/src/tonkadur/fate/v1/lang/instruction/PopElement.java b/src/core/src/tonkadur/fate/v1/lang/instruction/PopElement.java
deleted file mode 100644
index 4d64652..0000000
--- a/src/core/src/tonkadur/fate/v1/lang/instruction/PopElement.java
+++ /dev/null
@@ -1,117 +0,0 @@
-package tonkadur.fate.v1.lang.instruction;
-
-import tonkadur.parser.Origin;
-import tonkadur.parser.ParsingError;
-
-import tonkadur.fate.v1.lang.type.PointerType;
-import tonkadur.fate.v1.lang.type.CollectionType;
-
-import tonkadur.fate.v1.lang.meta.InstructionVisitor;
-import tonkadur.fate.v1.lang.meta.Instruction;
-import tonkadur.fate.v1.lang.meta.Reference;
-import tonkadur.fate.v1.lang.meta.Computation;
-import tonkadur.fate.v1.lang.meta.RecurrentChecks;
-
-public class PopElement extends Instruction
-{
-   /***************************************************************************/
-   /**** MEMBERS **************************************************************/
-   /***************************************************************************/
-   protected final Computation storage_ptr;
-   protected final Reference collection;
-   protected final boolean is_from_left;
-
-   /***************************************************************************/
-   /**** PROTECTED ************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   protected PopElement
-   (
-      final Origin origin,
-      final Computation storage_ptr,
-      final Reference collection,
-      final boolean is_from_left
-   )
-   {
-      super(origin);
-
-      this.storage_ptr = storage_ptr;
-      this.collection = collection;
-      this.is_from_left = is_from_left;
-   }
-
-   /***************************************************************************/
-   /**** PUBLIC ***************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   public static PopElement build
-   (
-      final Origin origin,
-      final Computation storage_ptr,
-      final Reference collection,
-      final boolean is_from_left
-   )
-   throws ParsingError
-   {
-      RecurrentChecks.assert_is_a_collection(collection);
-      RecurrentChecks.assert_can_be_used_as
-      (
-         storage_ptr,
-         new PointerType
-         (
-            origin,
-            ((CollectionType) collection.get_type()).get_content_type(),
-            "auto generated"
-         )
-      );
-
-      return new PopElement(origin, storage_ptr, collection, is_from_left);
-   }
-
-   /**** Accessors ************************************************************/
-   @Override
-   public void get_visited_by (final InstructionVisitor iv)
-   throws Throwable
-   {
-      iv.visit_pop_element(this);
-   }
-
-   public Reference get_collection ()
-   {
-      return collection;
-   }
-
-   public Computation get_storage_pointer ()
-   {
-      return storage_ptr;
-   }
-
-   public boolean is_from_left ()
-   {
-      return is_from_left;
-   }
-
-   /**** Misc. ****************************************************************/
-   @Override
-   public String toString ()
-   {
-      final StringBuilder sb = new StringBuilder();
-
-      if (is_from_left)
-      {
-         sb.append("(PopLeftElement ");
-      }
-      else
-      {
-         sb.append("(PopRightElement ");
-      }
-
-      sb.append(collection.toString());
-
-      sb.append(" ");
-      sb.append(storage_ptr.toString());
-      sb.append(")");
-
-      return sb.toString();
-   }
-}
diff --git a/src/core/src/tonkadur/fate/v1/lang/instruction/PushElement.java b/src/core/src/tonkadur/fate/v1/lang/instruction/PushElement.java
deleted file mode 100644
index f07ef89..0000000
--- a/src/core/src/tonkadur/fate/v1/lang/instruction/PushElement.java
+++ /dev/null
@@ -1,113 +0,0 @@
-package tonkadur.fate.v1.lang.instruction;
-
-import tonkadur.parser.Origin;
-import tonkadur.parser.ParsingError;
-
-import tonkadur.fate.v1.lang.meta.InstructionVisitor;
-import tonkadur.fate.v1.lang.meta.Instruction;
-import tonkadur.fate.v1.lang.meta.Computation;
-import tonkadur.fate.v1.lang.meta.Reference;
-import tonkadur.fate.v1.lang.meta.RecurrentChecks;
-
-public class PushElement extends Instruction
-{
-   /***************************************************************************/
-   /**** MEMBERS **************************************************************/
-   /***************************************************************************/
-   protected final Computation element;
-   protected final Reference collection;
-   protected final boolean is_from_left;
-
-   /***************************************************************************/
-   /**** PROTECTED ************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   protected PushElement
-   (
-      final Origin origin,
-      final Computation element,
-      final Reference collection,
-      final boolean is_from_left
-   )
-   {
-      super(origin);
-
-      this.collection = collection;
-      this.element = element;
-      this.is_from_left = is_from_left;
-   }
-
-   /***************************************************************************/
-   /**** PUBLIC ***************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   public static PushElement build
-   (
-      final Origin origin,
-      final Computation element,
-      final Reference collection,
-      final boolean is_from_left
-   )
-   throws ParsingError
-   {
-      RecurrentChecks.assert_is_a_list_of(collection, element);
-
-      return new PushElement(origin, element, collection, is_from_left);
-   }
-
-   /**** Accessors ************************************************************/
-   @Override
-   public void get_visited_by (final InstructionVisitor iv)
-   throws Throwable
-   {
-      iv.visit_push_element(this);
-   }
-
-   public Reference get_collection ()
-   {
-      return collection;
-   }
-
-   public Computation get_element ()
-   {
-      return element;
-   }
-
-   public boolean  is_from_left ()
-   {
-      return is_from_left;
-   }
-
-   /**** Misc. ****************************************************************/
-   @Override
-   public String toString ()
-   {
-      final StringBuilder sb = new StringBuilder();
-
-      if (is_from_left)
-      {
-         sb.append("(LeftPushElement");
-      }
-      else
-      {
-         sb.append("(RightPushElement");
-      }
-
-      sb.append(System.lineSeparator());
-      sb.append(System.lineSeparator());
-
-      sb.append("element:");
-      sb.append(System.lineSeparator());
-      sb.append(element.toString());
-      sb.append(System.lineSeparator());
-      sb.append(System.lineSeparator());
-
-      sb.append("collection:");
-      sb.append(System.lineSeparator());
-      sb.append(collection.toString());
-
-      sb.append(")");
-
-      return sb.toString();
-   }
-}
diff --git a/src/core/src/tonkadur/fate/v1/lang/instruction/RemoveAllOfElement.java b/src/core/src/tonkadur/fate/v1/lang/instruction/RemoveAllOfElement.java
deleted file mode 100644
index 5384baa..0000000
--- a/src/core/src/tonkadur/fate/v1/lang/instruction/RemoveAllOfElement.java
+++ /dev/null
@@ -1,96 +0,0 @@
-package tonkadur.fate.v1.lang.instruction;
-
-import tonkadur.parser.Origin;
-import tonkadur.parser.ParsingError;
-
-import tonkadur.fate.v1.lang.meta.InstructionVisitor;
-import tonkadur.fate.v1.lang.meta.Instruction;
-import tonkadur.fate.v1.lang.meta.Computation;
-import tonkadur.fate.v1.lang.meta.Reference;
-import tonkadur.fate.v1.lang.meta.RecurrentChecks;
-
-public class RemoveAllOfElement extends Instruction
-{
-   /***************************************************************************/
-   /**** MEMBERS **************************************************************/
-   /***************************************************************************/
-   protected final Computation element;
-   protected final Reference collection;
-
-   /***************************************************************************/
-   /**** PROTECTED ************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   protected RemoveAllOfElement
-   (
-      final Origin origin,
-      final Computation element,
-      final Reference collection
-   )
-   {
-      super(origin);
-
-      this.collection = collection;
-      this.element = element;
-   }
-
-   /***************************************************************************/
-   /**** PUBLIC ***************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   public static RemoveAllOfElement build
-   (
-      final Origin origin,
-      final Computation element,
-      final Reference collection
-   )
-   throws ParsingError
-   {
-      RecurrentChecks.assert_is_a_collection_of(collection, element);
-
-      return new RemoveAllOfElement(origin, element, collection);
-   }
-
-   /**** Accessors ************************************************************/
-   @Override
-   public void get_visited_by (final InstructionVisitor iv)
-   throws Throwable
-   {
-      iv.visit_remove_all_of_element(this);
-   }
-
-   public Computation get_element ()
-   {
-      return element;
-   }
-
-   public Reference get_collection ()
-   {
-      return collection;
-   }
-
-   /**** Misc. ****************************************************************/
-   @Override
-   public String toString ()
-   {
-      final StringBuilder sb = new StringBuilder();
-
-      sb.append("(RemoveAllOfElement");
-      sb.append(System.lineSeparator());
-      sb.append(System.lineSeparator());
-
-      sb.append("element:");
-      sb.append(System.lineSeparator());
-      sb.append(element.toString());
-      sb.append(System.lineSeparator());
-      sb.append(System.lineSeparator());
-
-      sb.append("collection:");
-      sb.append(System.lineSeparator());
-      sb.append(collection.toString());
-
-      sb.append(")");
-
-      return sb.toString();
-   }
-}
diff --git a/src/core/src/tonkadur/fate/v1/lang/instruction/RemoveElement.java b/src/core/src/tonkadur/fate/v1/lang/instruction/RemoveElement.java
deleted file mode 100644
index d2a2e50..0000000
--- a/src/core/src/tonkadur/fate/v1/lang/instruction/RemoveElement.java
+++ /dev/null
@@ -1,96 +0,0 @@
-package tonkadur.fate.v1.lang.instruction;
-
-import tonkadur.parser.Origin;
-import tonkadur.parser.ParsingError;
-
-import tonkadur.fate.v1.lang.meta.InstructionVisitor;
-import tonkadur.fate.v1.lang.meta.Instruction;
-import tonkadur.fate.v1.lang.meta.Computation;
-import tonkadur.fate.v1.lang.meta.Reference;
-import tonkadur.fate.v1.lang.meta.RecurrentChecks;
-
-public class RemoveElement extends Instruction
-{
-   /***************************************************************************/
-   /**** MEMBERS **************************************************************/
-   /***************************************************************************/
-   protected final Computation element;
-   protected final Reference collection;
-
-   /***************************************************************************/
-   /**** PROTECTED ************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   protected RemoveElement
-   (
-      final Origin origin,
-      final Computation element,
-      final Reference collection
-   )
-   {
-      super(origin);
-
-      this.collection = collection;
-      this.element = element;
-   }
-
-   /***************************************************************************/
-   /**** PUBLIC ***************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   public static RemoveElement build
-   (
-      final Origin origin,
-      final Computation element,
-      final Reference collection
-   )
-   throws ParsingError
-   {
-      RecurrentChecks.assert_is_a_collection_of(collection, element);
-
-      return new RemoveElement(origin, element, collection);
-   }
-
-   /**** Accessors ************************************************************/
-   @Override
-   public void get_visited_by (final InstructionVisitor iv)
-   throws Throwable
-   {
-      iv.visit_remove_element(this);
-   }
-
-   public Computation get_element ()
-   {
-      return element;
-   }
-
-   public Reference get_collection ()
-   {
-      return collection;
-   }
-
-   /**** Misc. ****************************************************************/
-   @Override
-   public String toString ()
-   {
-      final StringBuilder sb = new StringBuilder();
-
-      sb.append("(RemoveElement");
-      sb.append(System.lineSeparator());
-      sb.append(System.lineSeparator());
-
-      sb.append("element:");
-      sb.append(System.lineSeparator());
-      sb.append(element.toString());
-      sb.append(System.lineSeparator());
-      sb.append(System.lineSeparator());
-
-      sb.append("collection:");
-      sb.append(System.lineSeparator());
-      sb.append(collection.toString());
-
-      sb.append(")");
-
-      return sb.toString();
-   }
-}
diff --git a/src/core/src/tonkadur/fate/v1/lang/instruction/RemoveElementAt.java b/src/core/src/tonkadur/fate/v1/lang/instruction/RemoveElementAt.java
deleted file mode 100644
index a036970..0000000
--- a/src/core/src/tonkadur/fate/v1/lang/instruction/RemoveElementAt.java
+++ /dev/null
@@ -1,99 +0,0 @@
-package tonkadur.fate.v1.lang.instruction;
-
-import tonkadur.parser.Origin;
-import tonkadur.parser.ParsingError;
-
-import tonkadur.fate.v1.lang.type.Type;
-
-import tonkadur.fate.v1.lang.meta.InstructionVisitor;
-import tonkadur.fate.v1.lang.meta.Instruction;
-import tonkadur.fate.v1.lang.meta.Computation;
-import tonkadur.fate.v1.lang.meta.Reference;
-import tonkadur.fate.v1.lang.meta.RecurrentChecks;
-
-public class RemoveElementAt extends Instruction
-{
-   /***************************************************************************/
-   /**** MEMBERS **************************************************************/
-   /***************************************************************************/
-   protected final Computation index;
-   protected final Reference collection;
-
-   /***************************************************************************/
-   /**** PROTECTED ************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   protected RemoveElementAt
-   (
-      final Origin origin,
-      final Computation index,
-      final Reference collection
-   )
-   {
-      super(origin);
-
-      this.collection = collection;
-      this.index = index;
-   }
-
-   /***************************************************************************/
-   /**** PUBLIC ***************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   public static RemoveElementAt build
-   (
-      final Origin origin,
-      final Computation index,
-      final Reference collection
-   )
-   throws ParsingError
-   {
-      RecurrentChecks.assert_is_a_collection(collection);
-      RecurrentChecks.assert_can_be_used_as(index, Type.INT);
-
-      return new RemoveElementAt(origin, index, collection);
-   }
-
-   /**** Accessors ************************************************************/
-   @Override
-   public void get_visited_by (final InstructionVisitor iv)
-   throws Throwable
-   {
-      iv.visit_remove_element_at(this);
-   }
-
-   public Computation get_index ()
-   {
-      return index;
-   }
-
-   public Reference get_collection ()
-   {
-      return collection;
-   }
-
-   /**** Misc. ****************************************************************/
-   @Override
-   public String toString ()
-   {
-      final StringBuilder sb = new StringBuilder();
-
-      sb.append("(RemoveElementAt");
-      sb.append(System.lineSeparator());
-      sb.append(System.lineSeparator());
-
-      sb.append("index:");
-      sb.append(System.lineSeparator());
-      sb.append(index.toString());
-      sb.append(System.lineSeparator());
-      sb.append(System.lineSeparator());
-
-      sb.append("collection:");
-      sb.append(System.lineSeparator());
-      sb.append(collection.toString());
-
-      sb.append(")");
-
-      return sb.toString();
-   }
-}
diff --git a/src/core/src/tonkadur/fate/v1/lang/instruction/RemoveElementsOf.java b/src/core/src/tonkadur/fate/v1/lang/instruction/RemoveElementsOf.java
deleted file mode 100644
index ca91e7a..0000000
--- a/src/core/src/tonkadur/fate/v1/lang/instruction/RemoveElementsOf.java
+++ /dev/null
@@ -1,105 +0,0 @@
-package tonkadur.fate.v1.lang.instruction;
-
-import tonkadur.parser.Origin;
-import tonkadur.parser.ParsingError;
-
-import tonkadur.fate.v1.lang.type.CollectionType;
-
-import tonkadur.fate.v1.lang.meta.InstructionVisitor;
-import tonkadur.fate.v1.lang.meta.Instruction;
-import tonkadur.fate.v1.lang.meta.Reference;
-import tonkadur.fate.v1.lang.meta.Computation;
-import tonkadur.fate.v1.lang.meta.RecurrentChecks;
-
-public class RemoveElementsOf extends Instruction
-{
-   /***************************************************************************/
-   /**** MEMBERS **************************************************************/
-   /***************************************************************************/
-   protected final Computation other_collection;
-   protected final Reference collection;
-
-   /***************************************************************************/
-   /**** PROTECTED ************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   protected RemoveElementsOf
-   (
-      final Origin origin,
-      final Computation other_collection,
-      final Reference collection
-   )
-   {
-      super(origin);
-
-      this.collection = collection;
-      this.other_collection = other_collection;
-   }
-
-   /***************************************************************************/
-   /**** PUBLIC ***************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   public static RemoveElementsOf build
-   (
-      final Origin origin,
-      final Computation other_collection,
-      final Reference collection
-   )
-   throws ParsingError
-   {
-      RecurrentChecks.assert_is_a_collection(collection);
-      RecurrentChecks.assert_is_a_collection(other_collection);
-      RecurrentChecks.assert_can_be_used_as
-      (
-         other_collection.get_origin(),
-         ((CollectionType) other_collection.get_type()).get_content_type(),
-         ((CollectionType) collection.get_type()).get_content_type()
-      );
-
-      return new RemoveElementsOf(origin, other_collection, collection);
-   }
-
-   /**** Accessors ************************************************************/
-   @Override
-   public void get_visited_by (final InstructionVisitor iv)
-   throws Throwable
-   {
-      iv.visit_remove_elements_of(this);
-   }
-
-   public Computation get_source_collection ()
-   {
-      return other_collection;
-   }
-
-   public Reference get_target_collection ()
-   {
-      return collection;
-   }
-
-   /**** Misc. ****************************************************************/
-   @Override
-   public String toString ()
-   {
-      final StringBuilder sb = new StringBuilder();
-
-      sb.append("(RemoveElementsOf");
-      sb.append(System.lineSeparator());
-      sb.append(System.lineSeparator());
-
-      sb.append("other_collection:");
-      sb.append(System.lineSeparator());
-      sb.append(other_collection.toString());
-      sb.append(System.lineSeparator());
-      sb.append(System.lineSeparator());
-
-      sb.append("collection:");
-      sb.append(System.lineSeparator());
-      sb.append(collection.toString());
-
-      sb.append(")");
-
-      return sb.toString();
-   }
-}
diff --git a/src/core/src/tonkadur/fate/v1/lang/instruction/ReverseList.java b/src/core/src/tonkadur/fate/v1/lang/instruction/ReverseList.java
deleted file mode 100644
index 79caeac..0000000
--- a/src/core/src/tonkadur/fate/v1/lang/instruction/ReverseList.java
+++ /dev/null
@@ -1,75 +0,0 @@
-package tonkadur.fate.v1.lang.instruction;
-
-import tonkadur.parser.Origin;
-import tonkadur.parser.ParsingError;
-
-import tonkadur.fate.v1.lang.meta.InstructionVisitor;
-import tonkadur.fate.v1.lang.meta.Instruction;
-import tonkadur.fate.v1.lang.meta.Reference;
-import tonkadur.fate.v1.lang.meta.RecurrentChecks;
-
-public class ReverseList extends Instruction
-{
-   /***************************************************************************/
-   /**** MEMBERS **************************************************************/
-   /***************************************************************************/
-   protected final Reference collection;
-
-   /***************************************************************************/
-   /**** PROTECTED ************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   protected ReverseList
-   (
-      final Origin origin,
-      final Reference collection
-   )
-   {
-      super(origin);
-
-      this.collection = collection;
-   }
-
-   /***************************************************************************/
-   /**** PUBLIC ***************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   public static ReverseList build
-   (
-      final Origin origin,
-      final Reference collection
-   )
-   throws ParsingError
-   {
-      RecurrentChecks.assert_is_a_list(collection);
-
-      return new ReverseList(origin, collection);
-   }
-
-   /**** Accessors ************************************************************/
-   @Override
-   public void get_visited_by (final InstructionVisitor iv)
-   throws Throwable
-   {
-      iv.visit_reverse_list(this);
-   }
-
-   public Reference get_collection ()
-   {
-      return collection;
-   }
-
-   /**** Misc. ****************************************************************/
-   @Override
-   public String toString ()
-   {
-      final StringBuilder sb = new StringBuilder();
-
-      sb.append("(ReverseList ");
-      sb.append(collection.toString());
-
-      sb.append(")");
-
-      return sb.toString();
-   }
-}
diff --git a/src/core/src/tonkadur/fate/v1/lang/instruction/SetFields.java b/src/core/src/tonkadur/fate/v1/lang/instruction/SetFields.java
index db2fb73..fff2a2b 100644
--- a/src/core/src/tonkadur/fate/v1/lang/instruction/SetFields.java
+++ b/src/core/src/tonkadur/fate/v1/lang/instruction/SetFields.java
@@ -8,7 +8,6 @@ import tonkadur.functional.Cons;
 
 import tonkadur.fate.v1.lang.meta.InstructionVisitor;
 import tonkadur.fate.v1.lang.meta.Instruction;
-import tonkadur.fate.v1.lang.meta.Reference;
 import tonkadur.fate.v1.lang.meta.Computation;
 
 public class SetFields extends Instruction
@@ -16,7 +15,7 @@ public class SetFields extends Instruction
    /***************************************************************************/
    /**** MEMBERS **************************************************************/
    /***************************************************************************/
-   protected final Reference target;
+   protected final Computation target;
    protected final List<Cons<String, Computation>> field_assignments;
 
    /***************************************************************************/
@@ -30,7 +29,7 @@ public class SetFields extends Instruction
    public SetFields
    (
       final Origin origin,
-      final Reference target,
+      final Computation target,
       final List<Cons<String, Computation>> field_assignments
    )
    {
@@ -48,7 +47,7 @@ public class SetFields extends Instruction
       iv.visit_set_fields(this);
    }
 
-   public Reference get_target ()
+   public Computation get_target ()
    {
       return target;
    }
diff --git a/src/core/src/tonkadur/fate/v1/lang/instruction/SetValue.java b/src/core/src/tonkadur/fate/v1/lang/instruction/SetValue.java
index 2e4dd79..672756a 100644
--- a/src/core/src/tonkadur/fate/v1/lang/instruction/SetValue.java
+++ b/src/core/src/tonkadur/fate/v1/lang/instruction/SetValue.java
@@ -7,7 +7,6 @@ import tonkadur.parser.ParsingError;
 import tonkadur.fate.v1.lang.meta.InstructionVisitor;
 import tonkadur.fate.v1.lang.meta.Instruction;
 import tonkadur.fate.v1.lang.meta.Computation;
-import tonkadur.fate.v1.lang.meta.Reference;
 import tonkadur.fate.v1.lang.meta.RecurrentChecks;
 
 public class SetValue extends Instruction
@@ -16,7 +15,7 @@ public class SetValue extends Instruction
    /**** MEMBERS **************************************************************/
    /***************************************************************************/
    protected final Computation element;
-   protected final Reference value_reference;
+   protected final Computation value_reference;
 
    /***************************************************************************/
    /**** PROTECTED ************************************************************/
@@ -26,7 +25,7 @@ public class SetValue extends Instruction
    (
       final Origin origin,
       final Computation element,
-      final Reference value_reference
+      final Computation value_reference
    )
    {
       super(origin);
@@ -43,7 +42,7 @@ public class SetValue extends Instruction
    (
       final Origin origin,
       final Computation element,
-      final Reference value_reference
+      final Computation value_reference
    )
    throws ParsingError
    {
@@ -65,7 +64,7 @@ public class SetValue extends Instruction
       return element;
    }
 
-   public Reference get_reference ()
+   public Computation get_reference ()
    {
       return value_reference;
    }
diff --git a/src/core/src/tonkadur/fate/v1/lang/instruction/Shuffle.java b/src/core/src/tonkadur/fate/v1/lang/instruction/Shuffle.java
deleted file mode 100644
index bf12da6..0000000
--- a/src/core/src/tonkadur/fate/v1/lang/instruction/Shuffle.java
+++ /dev/null
@@ -1,75 +0,0 @@
-package tonkadur.fate.v1.lang.instruction;
-
-import tonkadur.parser.Origin;
-import tonkadur.parser.ParsingError;
-
-import tonkadur.fate.v1.lang.meta.InstructionVisitor;
-import tonkadur.fate.v1.lang.meta.Instruction;
-import tonkadur.fate.v1.lang.meta.Reference;
-import tonkadur.fate.v1.lang.meta.RecurrentChecks;
-
-public class Shuffle extends Instruction
-{
-   /***************************************************************************/
-   /**** MEMBERS **************************************************************/
-   /***************************************************************************/
-   protected final Reference collection;
-
-   /***************************************************************************/
-   /**** PROTECTED ************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   protected Shuffle
-   (
-      final Origin origin,
-      final Reference collection
-   )
-   {
-      super(origin);
-
-      this.collection = collection;
-   }
-
-   /***************************************************************************/
-   /**** PUBLIC ***************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   public static Shuffle build
-   (
-      final Origin origin,
-      final Reference collection
-   )
-   throws ParsingError
-   {
-      RecurrentChecks.assert_is_a_list(collection);
-
-      return new Shuffle(origin, collection);
-   }
-
-   /**** Accessors ************************************************************/
-   @Override
-   public void get_visited_by (final InstructionVisitor iv)
-   throws Throwable
-   {
-      iv.visit_shuffle(this);
-   }
-
-   public Reference get_collection ()
-   {
-      return collection;
-   }
-
-   /**** Misc. ****************************************************************/
-   @Override
-   public String toString ()
-   {
-      final StringBuilder sb = new StringBuilder();
-
-      sb.append("(Shuffle ");
-      sb.append(collection.toString());
-
-      sb.append(")");
-
-      return sb.toString();
-   }
-}
diff --git a/src/core/src/tonkadur/fate/v1/lang/instruction/Sort.java b/src/core/src/tonkadur/fate/v1/lang/instruction/Sort.java
deleted file mode 100644
index f19a4fc..0000000
--- a/src/core/src/tonkadur/fate/v1/lang/instruction/Sort.java
+++ /dev/null
@@ -1,127 +0,0 @@
-package tonkadur.fate.v1.lang.instruction;
-
-import java.util.ArrayList;
-import java.util.List;
-
-import tonkadur.parser.Origin;
-import tonkadur.parser.ParsingError;
-
-import tonkadur.fate.v1.lang.type.Type;
-import tonkadur.fate.v1.lang.type.CollectionType;
-
-import tonkadur.fate.v1.lang.meta.Computation;
-import tonkadur.fate.v1.lang.meta.Instruction;
-import tonkadur.fate.v1.lang.meta.InstructionVisitor;
-import tonkadur.fate.v1.lang.meta.Reference;
-import tonkadur.fate.v1.lang.meta.RecurrentChecks;
-
-public class Sort extends Instruction
-{
-   /***************************************************************************/
-   /**** MEMBERS **************************************************************/
-   /***************************************************************************/
-   protected final List<Computation> extra_params;
-   protected final Computation lambda_function;
-   protected final Reference collection;
-
-   /***************************************************************************/
-   /**** PROTECTED ************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   protected Sort
-   (
-      final Origin origin,
-      final Computation lambda_function,
-      final Reference collection,
-      final List<Computation> extra_params
-   )
-   {
-      super(origin);
-
-      this.lambda_function = lambda_function;
-      this.collection = collection;
-      this.extra_params = extra_params;
-   }
-
-   /***************************************************************************/
-   /**** PUBLIC ***************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   public static Sort build
-   (
-      final Origin origin,
-      final Computation lambda_function,
-      final Reference collection,
-      final List<Computation> extra_params
-   )
-   throws Throwable
-   {
-      final List<Type> types_in;
-
-      types_in = new ArrayList<Type>();
-
-      RecurrentChecks.assert_is_a_list(collection);
-
-      types_in.add(((CollectionType) collection.get_type()).get_content_type());
-      types_in.add(types_in.get(0));
-
-      for (final Computation c: extra_params)
-      {
-         types_in.add(c.get_type());
-      }
-
-      RecurrentChecks.assert_lambda_matches_types
-      (
-         lambda_function,
-         Type.INT,
-         types_in
-      );
-
-      return new Sort(origin, lambda_function, collection, extra_params);
-   }
-
-   /**** Accessors ************************************************************/
-   @Override
-   public void get_visited_by (final InstructionVisitor iv)
-   throws Throwable
-   {
-      iv.visit_sort(this);
-   }
-
-   public Computation get_lambda_function ()
-   {
-      return lambda_function;
-   }
-
-   public Reference get_collection ()
-   {
-      return collection;
-   }
-
-   public List<Computation> get_extra_parameters ()
-   {
-      return extra_params;
-   }
-
-   /**** Misc. ****************************************************************/
-   @Override
-   public String toString ()
-   {
-      final StringBuilder sb = new StringBuilder();
-
-      sb.append("(Sort ");
-      sb.append(lambda_function.toString());
-      sb.append(" ");
-      sb.append(collection.toString());
-
-      for (final Computation c: extra_params)
-      {
-         sb.append(" ");
-         sb.append(c.toString());
-      }
-
-      sb.append(")");
-
-      return sb.toString();
-   }
-}
diff --git a/src/core/src/tonkadur/fate/v1/lang/instruction/SubList.java b/src/core/src/tonkadur/fate/v1/lang/instruction/SubList.java
deleted file mode 100644
index a80325b..0000000
--- a/src/core/src/tonkadur/fate/v1/lang/instruction/SubList.java
+++ /dev/null
@@ -1,101 +0,0 @@
-package tonkadur.fate.v1.lang.instruction;
-
-import tonkadur.parser.Origin;
-import tonkadur.parser.ParsingError;
-
-import tonkadur.fate.v1.lang.type.Type;
-
-import tonkadur.fate.v1.lang.meta.Computation;
-import tonkadur.fate.v1.lang.meta.Instruction;
-import tonkadur.fate.v1.lang.meta.InstructionVisitor;
-import tonkadur.fate.v1.lang.meta.Reference;
-import tonkadur.fate.v1.lang.meta.RecurrentChecks;
-
-public class SubList extends Instruction
-{
-   /***************************************************************************/
-   /**** MEMBERS **************************************************************/
-   /***************************************************************************/
-   protected final Computation start;
-   protected final Computation end;
-   protected final Reference collection;
-
-   /***************************************************************************/
-   /**** PROTECTED ************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   protected SubList
-   (
-      final Origin origin,
-      final Computation start,
-      final Computation end,
-      final Reference collection
-   )
-   {
-      super(origin);
-
-      this.start = start;
-      this.end = end;
-      this.collection = collection;
-   }
-
-   /***************************************************************************/
-   /**** PUBLIC ***************************************************************/
-   /***************************************************************************/
-   /**** Constructors *********************************************************/
-   public static SubList build
-   (
-      final Origin origin,
-      final Computation start,
-      final Computation end,
-      final Reference collection
-   )
-   throws Throwable
-   {
-      RecurrentChecks.assert_is_a_collection(collection);
-      RecurrentChecks.assert_can_be_used_as(start, Type.INT);
-      RecurrentChecks.assert_can_be_used_as(end, Type.INT);
-
-      return new SubList(origin, start, end, collection);
-   }
-
-   /**** Accessors ************************************************************/
-   @Override
-   public void get_visited_by (final InstructionVisitor iv)
-   throws Throwable
-   {
-      iv.visit_sublist(this);
-   }
-
-   public Computation get_start_index ()
-   {
-      return start;
-   }
-
-   public Computation get_end_index ()
-   {
-      return end;
-   }
-
-   public Reference get_collection ()
-   {
-      return collection;
-   }
-
-   /**** Misc. ****************************************************************/
-   @Override
-   public String toString ()
-   {
-      final StringBuilder sb = new StringBuilder();
-
-      sb.append("(SubList ");
-      sb.append(start.toString());
-      sb.append(" ");
-      sb.append(end.toString());
-      sb.append(" ");
-      sb.append(collection.toString());
-      sb.append(")");
-
-      return sb.toString();
-   }
-}
diff --git a/src/core/src/tonkadur/fate/v1/lang/instruction/Allocate.java b/src/core/src/tonkadur/fate/v1/lang/instruction/generic/Allocate.java
index 32c7241..cc159f5 100644
--- a/src/core/src/tonkadur/fate/v1/lang/instruction/Allocate.java
+++ b/src/core/src/tonkadur/fate/v1/lang/instruction/generic/Allocate.java
@@ -1,6 +1,8 @@
-package tonkadur.fate.v1.lang.instruction;
+package tonkadur.fate.v1.lang.instruction.generic;
 
+import java.util.ArrayList;
 import java.util.Collections;
+import java.util.List;
 
 import tonkadur.error.ErrorManager;
 
@@ -12,16 +14,51 @@ import tonkadur.fate.v1.error.InvalidTypeException;
 import tonkadur.fate.v1.lang.type.Type;
 import tonkadur.fate.v1.lang.type.PointerType;
 
-import tonkadur.fate.v1.lang.meta.InstructionVisitor;
-import tonkadur.fate.v1.lang.meta.Instruction;
-import tonkadur.fate.v1.lang.meta.Reference;
+import tonkadur.fate.v1.lang.meta.Computation;
 
-public class Allocate extends Instruction
+import tonkadur.fate.v1.lang.instruction.GenericInstruction;
+
+public class Allocate extends GenericInstruction
 {
+   protected static final Allocate ARCHETYPE;
+
+   static
+   {
+      final List<String> aliases;
+
+      aliases = new ArrayList<String>();
+
+      ARCHETYPE =
+         new Allocate
+         (
+            Origin.BASE_LANGUAGE,
+            null,
+            null
+         );
+
+      aliases.add("allocate");
+      aliases.add("alloc");
+      aliases.add("malloc");
+      aliases.add("malloc");
+      aliases.add("new");
+      aliases.add("create");
+
+      try
+      {
+         ARCHETYPE.register(aliases, null);
+      }
+      catch (final Exception e)
+      {
+         e.printStackTrace();
+
+         System.exit(-1);
+      }
+   }
+
    /***************************************************************************/
    /**** MEMBERS **************************************************************/
    /***************************************************************************/
-   protected final Reference target;
+   protected final Computation target;
    protected final Type allocated_type;
 
    /***************************************************************************/
@@ -32,10 +69,10 @@ public class Allocate extends Instruction
    (
       final Origin origin,
       final Type allocated_type,
-      final Reference target
+      final Computation target
    )
    {
-      super(origin);
+      super(origin, "allocate");
 
       this.allocated_type = allocated_type;
       this.target = target;
@@ -45,11 +82,24 @@ public class Allocate extends Instruction
    /**** PUBLIC ***************************************************************/
    /***************************************************************************/
    /**** Constructors *********************************************************/
-   public static Allocate build (final Origin origin, final Reference target)
-   throws ParsingError
+   @Override
+   public GenericInstruction build
+   (
+      final Origin origin,
+      final List<Computation> call_parameters,
+      final Object _constructor_parameter
+   )
+   throws Throwable
    {
       final Type target_type;
 
+      if (call_parameters.size() != 1)
+      {
+         // Error.
+      }
+
+      call_parameters.get(0).expect_non_string();
+
       target_type = target.get_type();
 
       if (target_type instanceof PointerType)
@@ -80,14 +130,7 @@ public class Allocate extends Instruction
    }
 
    /**** Accessors ************************************************************/
-   @Override
-   public void get_visited_by (final InstructionVisitor iv)
-   throws Throwable
-   {
-      iv.visit_allocate(this);
-   }
-
-   public Reference get_target ()
+   public Computation get_target ()
    {
       return target;
    }
diff --git a/src/core/src/tonkadur/fate/v1/lang/instruction/Clear.java b/src/core/src/tonkadur/fate/v1/lang/instruction/generic/Clear.java
index fe8943f..124f3f8 100644
--- a/src/core/src/tonkadur/fate/v1/lang/instruction/Clear.java
+++ b/src/core/src/tonkadur/fate/v1/lang/instruction/generic/Clear.java
@@ -1,15 +1,47 @@
 package tonkadur.fate.v1.lang.instruction;
 
+import java.util.List;
+import java.util.ArrayList;
+
 import tonkadur.parser.Origin;
 import tonkadur.parser.ParsingError;
 
-import tonkadur.fate.v1.lang.meta.InstructionVisitor;
-import tonkadur.fate.v1.lang.meta.Instruction;
 import tonkadur.fate.v1.lang.meta.Computation;
 import tonkadur.fate.v1.lang.meta.RecurrentChecks;
 
-public class Clear extends Instruction
+public class Clear extends GenericInstruction
 {
+   protected static final Clear ARCHETYPE;
+
+   static
+   {
+      final List<String> aliases;
+
+      ARCHETYPE = new Clear(Origin.BASE_LANGUAGE, null);
+
+      aliases = new ArrayList<String>();
+
+      aliases.add("clear");
+      aliases.add("empty");
+
+      aliases.add("list:clear");
+      aliases.add("list:empty");
+
+      aliases.add("set:clear");
+      aliases.add("set:empty");
+
+      try
+      {
+         ARCHETYPE.register(aliases, null);
+      }
+      catch (final Exception e)
+      {
+         e.printStackTrace();
+
+         System.exit(-1);
+      }
+   }
+
    /***************************************************************************/
    /**** MEMBERS **************************************************************/
    /***************************************************************************/
@@ -25,7 +57,7 @@ public class Clear extends Instruction
       final Computation collection
    )
    {
-      super(origin);
+      super(origin, "clear");
 
       this.collection = collection;
    }
@@ -34,26 +66,32 @@ public class Clear extends Instruction
    /**** PUBLIC ***************************************************************/
    /***************************************************************************/
    /**** Constructors *********************************************************/
-   public static Clear build
+   @Override
+   public GenericInstruction build
    (
       final Origin origin,
-      final Computation collection
+      final List<Computation> call_parameters,
+      final Object _constructor_parameter
    )
-   throws ParsingError
+   throws Throwable
    {
+      final Computation collection;
+
+      if (call_parameters.size() != 1)
+      {
+         // Error.
+      }
+
+      collection = call_parameters.get(0);
+
+      collection.expect_non_string();
+
       RecurrentChecks.assert_is_a_collection(collection);
 
       return new Clear(origin, collection);
    }
 
    /**** Accessors ************************************************************/
-   @Override
-   public void get_visited_by (final InstructionVisitor iv)
-   throws Throwable
-   {
-      iv.visit_clear(this);
-   }
-
    public Computation get_collection ()
    {
       return collection;
diff --git a/src/core/src/tonkadur/fate/v1/lang/instruction/generic/Free.java b/src/core/src/tonkadur/fate/v1/lang/instruction/generic/Free.java
new file mode 100644
index 0000000..64e02cf
--- /dev/null
+++ b/src/core/src/tonkadur/fate/v1/lang/instruction/generic/Free.java
@@ -0,0 +1,136 @@
+package tonkadur.fate.v1.lang.instruction;
+
+import java.util.List;
+import java.util.ArrayList;
+import java.util.Collections;
+
+import tonkadur.error.ErrorManager;
+
+import tonkadur.parser.Origin;
+
+import tonkadur.fate.v1.error.InvalidTypeException;
+
+import tonkadur.fate.v1.lang.type.Type;
+import tonkadur.fate.v1.lang.type.PointerType;
+
+import tonkadur.fate.v1.lang.meta.Computation;
+
+import tonkadur.fate.v1.lang.instruction.GenericInstruction;
+
+public class Free extends GenericInstruction
+{
+   protected static final Free ARCHETYPE;
+
+   static
+   {
+      final List<String> aliases;
+
+      aliases = new ArrayList<String>();
+
+      ARCHETYPE =
+         new Free
+         (
+            Origin.BASE_LANGUAGE,
+            null
+         );
+
+      aliases.add("free");
+      aliases.add("delete");
+      aliases.add("destroy");
+
+      try
+      {
+         ARCHETYPE.register(aliases, null);
+      }
+      catch (final Exception e)
+      {
+         e.printStackTrace();
+
+         System.exit(-1);
+      }
+   }
+   /***************************************************************************/
+   /**** MEMBERS **************************************************************/
+   /***************************************************************************/
+   protected final Computation value_reference;
+
+   /***************************************************************************/
+   /**** PROTECTED ************************************************************/
+   /***************************************************************************/
+   /**** Constructors *********************************************************/
+
+   /***************************************************************************/
+   /**** PUBLIC ***************************************************************/
+   /***************************************************************************/
+   /**** Constructors *********************************************************/
+   protected Free (final Origin origin, final Computation value_reference)
+   {
+      super(origin, "free");
+
+      this.value_reference = value_reference;
+   }
+
+   @Override
+   public GenericInstruction build
+   (
+      final Origin origin,
+      final List<Computation> call_parameters,
+      final Object _constructor_parameter
+   )
+   throws Throwable
+   {
+      final Computation target;
+      final Type target_type;
+
+      if (call_parameters.size() != 1)
+      {
+         // Error.
+      }
+
+      call_parameters.get(0).expect_non_string();
+
+      target = call_parameters.get(0);
+
+      target_type = target.get_type();
+
+      if (target_type instanceof PointerType)
+      {
+         return new Free(origin, target);
+      }
+
+      ErrorManager.handle
+      (
+         new InvalidTypeException
+         (
+            origin,
+            target_type,
+            Collections.singletonList
+            (
+               new PointerType(origin, Type.ANY, "Any Pointer")
+            )
+         )
+      );
+
+      return new Free(origin, target);
+   }
+
+   /**** Accessors ************************************************************/
+   public Computation get_reference ()
+   {
+      return value_reference;
+   }
+
+   /**** Misc. ****************************************************************/
+   @Override
+   public String toString ()
+   {
+      final StringBuilder sb = new StringBuilder();
+
+      sb.append("(Free ");
+      sb.append(value_reference.toString());
+
+      sb.append(")");
+
+      return sb.toString();
+   }
+}
diff --git a/src/core/src/tonkadur/fate/v1/lang/meta/Computation.java b/src/core/src/tonkadur/fate/v1/lang/meta/Computation.java
index 082478e..303dfd1 100644
--- a/src/core/src/tonkadur/fate/v1/lang/meta/Computation.java
+++ b/src/core/src/tonkadur/fate/v1/lang/meta/Computation.java
@@ -37,6 +37,14 @@ public abstract class Computation extends Node
       return type;
    }
 
+   public void expect_non_string ()
+   {
+   }
+
+   public void expect_string ()
+   {
+   }
+
    /**** Misc. ****************************************************************/
    @Override
    public String toString ()
diff --git a/src/core/src/tonkadur/fate/v1/lang/meta/ComputationVisitor.java b/src/core/src/tonkadur/fate/v1/lang/meta/ComputationVisitor.java
index 5d04922..25cdeea 100644
--- a/src/core/src/tonkadur/fate/v1/lang/meta/ComputationVisitor.java
+++ b/src/core/src/tonkadur/fate/v1/lang/meta/ComputationVisitor.java
@@ -4,36 +4,12 @@ import tonkadur.fate.v1.lang.computation.*;
 
 public interface ComputationVisitor
 {
-   public void visit_extra_computation (final ExtraComputationInstance n)
-   throws Throwable;
-
-   public void visit_at_reference (final AtReference n)
-   throws Throwable;
-
-   public void visit_text_join (final TextJoin n)
-   throws Throwable;
-
-   public void visit_access (final Access n)
-   throws Throwable;
-
-   public void visit_access_pointer (final AccessPointer n)
-   throws Throwable;
-
    public void visit_field_access (final FieldAccess n)
    throws Throwable;
 
-   public void visit_access_as_reference (final AccessAsReference n)
-   throws Throwable;
-
    public void visit_cast (final Cast n)
    throws Throwable;
 
-   public void visit_cons (final ConsComputation n)
-   throws Throwable;
-
-   public void visit_fold (final Fold n)
-   throws Throwable;
-
    public void visit_default (final Default n)
    throws Throwable;
 
@@ -46,51 +22,24 @@ public interface ComputationVisitor
    public void visit_constant (final Constant n)
    throws Throwable;
 
-   public void visit_count_operator (final CountOperator n)
-   throws Throwable;
-
-   public void visit_field_reference (final FieldReference n)
-   throws Throwable;
-
    public void visit_if_else_value (final IfElseValue n)
    throws Throwable;
 
-   public void visit_is_member_operator (final IsMemberOperator n)
-   throws Throwable;
-
-   public void visit_index_of_operator (final IndexOfOperator n)
-   throws Throwable;
-
-   public void visit_size_operator (final SizeOperator n)
-   throws Throwable;
-
    public void visit_lambda_expression (final LambdaExpression n)
    throws Throwable;
 
-   public void visit_lambda_evaluation (final LambdaEvaluation n)
-   throws Throwable;
-
    public void visit_let (final Let n)
    throws Throwable;
 
-   public void visit_is_empty (final IsEmpty n)
-   throws Throwable;
-
    public void visit_newline (final Newline n)
    throws Throwable;
 
-   public void visit_operation (final Operation n)
-   throws Throwable;
-
    public void visit_sequence_reference (final SequenceReference n)
    throws Throwable;
 
    public void visit_paragraph (final Paragraph n)
    throws Throwable;
 
-   public void visit_address_operator (final AddressOperator n)
-   throws Throwable;
-
    public void visit_text_with_effect (final TextWithEffect n)
    throws Throwable;
 
@@ -100,78 +49,12 @@ public interface ComputationVisitor
    public void visit_variable_reference (final VariableReference n)
    throws Throwable;
 
-   public void visit_car_cdr (final CarCdr n)
-   throws Throwable;
-
-   public void visit_add_element (final AddElementComputation n)
-   throws Throwable;
-
-   public void visit_add_element_at (final AddElementAtComputation n)
-   throws Throwable;
-
-   public void visit_add_elements_of (final AddElementsOfComputation n)
-   throws Throwable;
-
-   public void visit_remove_elements_of (final RemoveElementsOfComputation n)
-   throws Throwable;
-
-   public void visit_map (final MapComputation n)
-   throws Throwable;
-
-   public void visit_indexed_map (final IndexedMapComputation n)
-   throws Throwable;
-
-   public void visit_sort (final SortComputation n)
-   throws Throwable;
-
-   public void visit_range (final Range n)
-   throws Throwable;
-
-   public void visit_remove_all_of_element
-   (
-      final RemoveAllOfElementComputation n
-   )
-   throws Throwable;
-
-   public void visit_remove_element_at (final RemoveElementAtComputation n)
-   throws Throwable;
-
-   public void visit_remove_element (final RemoveElementComputation n)
-   throws Throwable;
-
-   public void visit_reverse_list (final ReverseListComputation n)
-   throws Throwable;
-
-   public void visit_shuffle (final ShuffleComputation n)
-   throws Throwable;
-
-   public void visit_merge (final MergeComputation n)
-   throws Throwable;
-
-   public void visit_indexed_merge (final IndexedMergeComputation n)
-   throws Throwable;
-
-   public void visit_filter (final FilterComputation n)
-   throws Throwable;
-
-   public void visit_indexed_filter (final IndexedFilterComputation n)
-   throws Throwable;
-
-   public void visit_sublist (final SubListComputation n)
-   throws Throwable;
-
-   public void visit_partition (final PartitionComputation n)
-   throws Throwable;
-
-   public void visit_indexed_partition (final IndexedPartitionComputation n)
-   throws Throwable;
-
-   public void visit_push_element (final PushElementComputation n)
+   public void visit_set_fields (final SetFieldsComputation n)
    throws Throwable;
 
-   public void visit_pop_element (final PopElementComputation n)
+   public void visit_extra_computation (final ExtraComputationInstance n)
    throws Throwable;
 
-   public void visit_set_fields (final SetFieldsComputation n)
+   public void visit_generic_computation (final GenericComputation n)
    throws Throwable;
 }
diff --git a/src/core/src/tonkadur/fate/v1/lang/meta/ExtraComputation.java b/src/core/src/tonkadur/fate/v1/lang/meta/ExtraComputation.java
index 6cefa54..f3a913e 100644
--- a/src/core/src/tonkadur/fate/v1/lang/meta/ExtraComputation.java
+++ b/src/core/src/tonkadur/fate/v1/lang/meta/ExtraComputation.java
@@ -13,6 +13,12 @@ import tonkadur.fate.v1.lang.type.Type;
 
 import tonkadur.fate.v1.lang.computation.ExtraComputationInstance;
 
+
+// This is for computations that are not compiled to Wyrd, but simply declared
+// in Fate and implemented by the wyrd interpreter.
+// This class should become something like a sub-GenericComputation thing.
+// Declaring an ExtraComputation should register an ExtraComputation object as a
+// GenericComputation, thus making it seamless from the user's point of view.
 public class ExtraComputation extends DeclaredEntity
 {
    protected static final ExtraComputation ANY;
diff --git a/src/core/src/tonkadur/fate/v1/lang/meta/InstructionVisitor.java b/src/core/src/tonkadur/fate/v1/lang/meta/InstructionVisitor.java
index 06c8525..8b43486 100644
--- a/src/core/src/tonkadur/fate/v1/lang/meta/InstructionVisitor.java
+++ b/src/core/src/tonkadur/fate/v1/lang/meta/InstructionVisitor.java
@@ -5,21 +5,6 @@ import tonkadur.fate.v1.lang.instruction.*;
 public interface InstructionVisitor
 {
    /* Instruction Nodes */
-   public void visit_add_element (final AddElement n)
-   throws Throwable;
-
-   public void visit_extra_instruction (final ExtraInstructionInstance n)
-   throws Throwable;
-
-   public void visit_add_element_at (final AddElementAt n)
-   throws Throwable;
-
-   public void visit_add_elements_of (final AddElementsOf n)
-   throws Throwable;
-
-   public void visit_remove_elements_of (final RemoveElementsOf n)
-   throws Throwable;
-
    public void visit_assert (final Assert n)
    throws Throwable;
 
@@ -32,12 +17,6 @@ public interface InstructionVisitor
    public void visit_done (final Done n)
    throws Throwable;
 
-   public void visit_allocate (final Allocate n)
-   throws Throwable;
-
-   public void visit_free (final Free n)
-   throws Throwable;
-
    public void visit_while (final While n)
    throws Throwable;
 
@@ -47,57 +26,9 @@ public interface InstructionVisitor
    public void visit_for (final For n)
    throws Throwable;
 
-   public void visit_remove_element_at (final RemoveElementAt n)
-   throws Throwable;
-
    public void visit_for_each (final ForEach n)
    throws Throwable;
 
-   public void visit_clear (final Clear n)
-   throws Throwable;
-
-   public void visit_map (final Map n)
-   throws Throwable;
-
-   public void visit_merge (final Merge n)
-   throws Throwable;
-
-   public void visit_indexed_merge (final IndexedMerge n)
-   throws Throwable;
-
-   public void visit_filter (final Filter n)
-   throws Throwable;
-
-   public void visit_indexed_filter (final IndexedFilter n)
-   throws Throwable;
-
-   public void visit_sublist (final SubList n)
-   throws Throwable;
-
-   public void visit_partition (final Partition n)
-   throws Throwable;
-
-   public void visit_indexed_partition (final IndexedPartition n)
-   throws Throwable;
-
-   public void visit_sort (final Sort n)
-   throws Throwable;
-
-   public void visit_indexed_map (final IndexedMap c)
-   throws Throwable;
-
-   public void visit_shuffle (final Shuffle c)
-   throws Throwable;
-
-   public void visit_pop_element (final PopElement c)
-   throws Throwable;
-
-   public void visit_push_element (final PushElement c)
-   throws Throwable;
-
-   public void visit_reverse_list (final ReverseList n)
-   throws Throwable;
-
    public void visit_cond_instruction (final CondInstruction n)
    throws Throwable;
 
@@ -131,12 +62,6 @@ public interface InstructionVisitor
    public void visit_event_option (final EventOption n)
    throws Throwable;
 
-   public void visit_remove_all_of_element (final RemoveAllOfElement n)
-   throws Throwable;
-
-   public void visit_remove_element (final RemoveElement n)
-   throws Throwable;
-
    public void visit_sequence_call (final SequenceCall n)
    throws Throwable;
 
@@ -157,4 +82,10 @@ public interface InstructionVisitor
 
    public void visit_set_fields (final SetFields n)
    throws Throwable;
+
+   public void visit_extra_instruction (final ExtraInstructionInstance n)
+   throws Throwable;
+
+   public void visit_generic_instruction (final GenericInstruction n)
+   throws Throwable;
 }
diff --git a/src/core/src/tonkadur/fate/v1/lang/meta/VariableFromWord.java b/src/core/src/tonkadur/fate/v1/lang/meta/VariableFromWord.java
index 97a7777..b6c933e 100644
--- a/src/core/src/tonkadur/fate/v1/lang/meta/VariableFromWord.java
+++ b/src/core/src/tonkadur/fate/v1/lang/meta/VariableFromWord.java
@@ -10,12 +10,11 @@ import java.util.ArrayList;
 import tonkadur.parser.Origin;
 import tonkadur.parser.ParsingError;
 
+import tonkadur.fate.v1.parser.Parser;
 import tonkadur.fate.v1.lang.Variable;
-import tonkadur.fate.v1.lang.World;
 
-import tonkadur.fate.v1.lang.computation.AccessAsReference;
 import tonkadur.fate.v1.lang.computation.Constant;
-import tonkadur.fate.v1.lang.computation.FieldReference;
+import tonkadur.fate.v1.lang.computation.FieldAccess;
 import tonkadur.fate.v1.lang.computation.VariableReference;
 
 import tonkadur.fate.v1.lang.type.CollectionType;
@@ -28,26 +27,25 @@ public class VariableFromWord
    /* Utility Class */
    private VariableFromWord () { }
 
-   public static Reference generate
+   public static Computation generate
    (
-      final World WORLD,
-      final Deque<Map<String, Variable>> LOCAL_VARIABLES,
+      final Parser parser,
       final Origin origin,
       final String word
    )
    throws ParsingError
    {
       final String[] subrefs;
-      Reference result;
+      Computation result;
       Variable target_var;
 
       subrefs = word.split("\\.");
 
-      target_var = LOCAL_VARIABLES.peekFirst().get(subrefs[0]);
+      target_var = parser.maybe_get_local_variable(subrefs[0]);
 
       if (target_var == null)
       {
-         target_var = WORLD.variables().get(origin, subrefs[0]);
+         target_var = parser.get_world().variables().get(origin, subrefs[0]);
       }
 
       result = new VariableReference(origin, target_var);
@@ -70,7 +68,7 @@ public class VariableFromWord
             {
                t = ((PointerType) t).get_referenced_type();
             }
-
+/*
             if (t instanceof CollectionType)
             {
                result =
@@ -91,7 +89,7 @@ public class VariableFromWord
                      Collections.singletonList(subref)
                   );
             }
-            else
+            else */
             {
                /* TODO: error */
                System.err.println("Unimplemented error in VariableFromWord.");
diff --git a/src/core/src/tonkadur/fate/v1/parser/FateParser.g4 b/src/core/src/tonkadur/fate/v1/parser/FateParser.g4
index 686fde2..d211d03 100644
--- a/src/core/src/tonkadur/fate/v1/parser/FateParser.g4
+++ b/src/core/src/tonkadur/fate/v1/parser/FateParser.g4
@@ -1394,7 +1394,7 @@ returns [List<Cons<Computation, Instruction>> result]
    condition = null;
 
    $result = new ArrayList<Cons<Computation, Instruction>>();
-   // TODO: pcd enable.
+   PARSER.enable_restricted_stack_of(pcd);
 }
 :
    (
@@ -1403,7 +1403,8 @@ returns [List<Cons<Computation, Instruction>> result]
             (L_PAREN WS* computation WS+)
             {
                condition = ($computation.result);
-               // TODO: pcd disable.
+
+               PARSER.disable_restricted_stack_of(pcd);
             }
          )
          |
@@ -1421,7 +1422,8 @@ returns [List<Cons<Computation, Instruction>> result]
                      ),
                      ($something_else.text).substring(1).trim()
                   );
-               // TODO: pcd disable.
+
+               PARSER.disable_restricted_stack_of(pcd);
             }
          )
       )
@@ -1444,14 +1446,14 @@ returns [List<Cons<Computation, Instruction>> result]
 @init
 {
    $result = new ArrayList<Cons<Computation, Instruction>>();
-   // todo: pcd enable
+   PARSER.enable_restricted_stack_of(pcd);
 }
 :
    (
       L_PAREN
          WS* computation
          {
-            //todo: pcd disable
+            PARSER.disable_restricted_stack_of(pcd);
          }
          WS* player_choice[pcd] WS*
       R_PAREN
@@ -1989,6 +1991,21 @@ returns [Computation result]
          );
    }
 
+   | VARIABLE_KW WORD WS* R_PAREN
+   {
+      $result =
+         VariableFromWord.generate
+         (
+            PARSER,
+            CONTEXT.get_origin_at
+            (
+               ($WORD.getLine()),
+               ($WORD.getCharPositionInLine())
+            ),
+            ($WORD.text)
+         );
+   }
+
    | IGNORE_ERROR_KW WORD WS+ computation WS* R_PAREN
    {
       $result = ($computation.result);
diff --git a/src/core/src/tonkadur/fate/v1/parser/Parser.java b/src/core/src/tonkadur/fate/v1/parser/Parser.java
index 3caa7b2..4fc978d 100644
--- a/src/core/src/tonkadur/fate/v1/parser/Parser.java
+++ b/src/core/src/tonkadur/fate/v1/parser/Parser.java
@@ -3,8 +3,10 @@ package tonkadur.fate.v1.parser;
 import java.io.IOException;
 
 import java.util.Collection;
+import java.util.ArrayDeque;
 import java.util.Deque;
 import java.util.HashSet;
+import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
@@ -15,6 +17,10 @@ import org.antlr.v4.runtime.CommonTokenStream;
 import tonkadur.parser.Context;
 import tonkadur.parser.Origin;
 
+import tonkadur.error.ErrorManager;
+
+import tonkadur.fate.v1.error.DuplicateLocalVariableException;
+
 import tonkadur.fate.v1.lang.Variable;
 import tonkadur.fate.v1.lang.World;
 
@@ -37,7 +43,7 @@ public class Parser
       breakable_levels = 0;
       continue_levels = 0;
 
-      context = new Context();
+      context = Context.BASE_LANGUAGE.clone();
    }
 
    public Origin get_origin_at (final int line, final int column)
@@ -90,7 +96,7 @@ public class Parser
    /**** LOCAL VARIABLES ******************************************************/
    public Variable maybe_get_local_variable (final String name)
    {
-      for (final Map<String, Variable> level: context_variables)
+      for (final Map<String, Variable> level: local_variables.stack)
       {
          final Variable v;
 
@@ -106,7 +112,7 @@ public class Parser
    }
 
    public void add_local_variables (final Map<String, Variable> collection)
-   throws Trowable
+   throws Throwable
    {
       for (final Variable variable: collection.values())
       {
@@ -115,11 +121,12 @@ public class Parser
    }
 
    public void add_local_variable (final Variable variable)
-   throws Trowable
+   throws Throwable
    {
-      final Map<String, Variable> current_hierarchy = local_variables.peek();
+      final Map<String, Variable> current_hierarchy;
       final Variable previous_entry;
 
+      current_hierarchy = local_variables.stack.peek();
       previous_entry = current_hierarchy.get(variable.get_name());
 
       if (previous_entry != null)
@@ -139,18 +146,18 @@ public class Parser
 
    public void increase_local_variables_hierarchy ()
    {
-      local_variables.push(new HashMap<String, Variable>());
+      local_variables.stack.push(new HashMap<String, Variable>());
    }
 
    public void decrease_local_variables_hierarchy ()
    {
-      local_variables.pop();
+      local_variables.stack.pop();
    }
 
    /* I don't think it's needed ATM. */
    public Collection<Variable> get_local_variables_at_current_hierarchy ()
    {
-      return local_variables.peek().values();
+      return local_variables.stack.peek().values();
    }
 
    public LocalVariables get_local_variables_stack ()
@@ -176,7 +183,7 @@ public class Parser
    {
       if ((e.getMessage() == null) || !e.getMessage().startsWith("Require"))
       {
-         kthrow
+         throw
             new ParseCancellationException
             (
                (
@@ -203,17 +210,9 @@ public class Parser
       tokens = new CommonTokenStream(lexer);
       parser = new FateParser(tokens);
 
-      if (origin != null)
-      {
-         context.push(origin);
-      }
-
+      context.push(origin.get_location(), filename);
       parser.fate_file(this);
-
-      if (origin != null)
-      {
-         context.pop();
-      }
+      context.pop();
 
       world.add_loaded_file(filename);
 
@@ -241,8 +240,26 @@ public class Parser
    }
 
 
-   public static class LocalVariables extends Deque<Map<String, Variable>>
+   /* Internal class to make moving LocalVariable objects around easier. */
+   public static class LocalVariables
    {
+      protected final Deque<Map<String, Variable>> stack;
+
+      protected LocalVariables ()
+      {
+         stack = new ArrayDeque<Map<String, Variable>>();
+      }
+
+      protected LocalVariables (final Deque<Map<String, Variable>> stack)
+      {
+         this.stack = stack.clone();
+      }
+
+      @Override
+      public LocalVariables clone ()
+      {
+         return new LocalVariables(stack);
+      }
    }
 
    public static class PlayerChoiceData
@@ -283,7 +300,7 @@ public class Parser
       {
          for (final Set<String> variable_names: player_choice_variable_names)
          {
-            if (variables_names.has(name))
+            if (variable_names.contains(name))
             {
                return true;
             }
diff --git a/src/core/src/tonkadur/parser/Location.java b/src/core/src/tonkadur/parser/Location.java
index 8e86a95..af89e7b 100644
--- a/src/core/src/tonkadur/parser/Location.java
+++ b/src/core/src/tonkadur/parser/Location.java
@@ -123,4 +123,11 @@ public class Location
    {
       return (filename.hashCode() + line + column);
    }
+
+
+   @Override
+   public Location clone ()
+   {
+      return new Location(is_base_language, directory, filename, line, column);
+   }
 }
diff --git a/src/core/src/tonkadur/parser/Origin.java b/src/core/src/tonkadur/parser/Origin.java
index 9d41fac..99f1cb4 100644
--- a/src/core/src/tonkadur/parser/Origin.java
+++ b/src/core/src/tonkadur/parser/Origin.java
@@ -48,4 +48,10 @@ public class Origin
 
       return sb.toString();
    }
+
+   @Override
+   public Origin clone ()
+   {
+      return new Origin(context.clone(), location.clone());
+   }
 }