First shot at storable procedures.

15 files changed, 974 insertions, 3 deletions

diff --git a/data/unit-testing/merge.fate b/data/unit-testing/merge.fate
index ba40724..4915ff8 100644
--- a/data/unit-testing/merge.fate
+++ b/data/unit-testing/merge.fate
@@ -516,7 +516,7 @@
 )
 
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
-;;; INDEXED TEST 1 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+;;; INDEXED TEST 1 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 For reference, the values found in the sets are:
 (for (set i 0) (=< i 30) (set i (+ i 1))
@@ -797,10 +797,56 @@ For reference, the values found in the sets are:
 )
 
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
-;;; SAFE TEST 0 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+;;; SAFE TEST 0 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+(global (list int) sli0)
+(global (list int) sli1)
+(global (list int) sli2)
+(global (list int) sli3)
 
-(assert (false) [FAILED] TODO: safe merge tests.)
+(set sli0
+   (safe_merge_to_list
+      (lambda
+         (
+            (int a)
+            (int b)
+         )
+         (- a b)
+      )
+      999
+      (range 0 10 1)
+      1
+      (default (list int))
+   )
+)
+
+(set sli1
+   (safe_merge_to_list
+      (lambda
+         (
+            (int a)
+            (int b)
+         )
+         (- b a)
+      )
+      1
+      (default (list int))
+      999
+      (range 0 10 1)
+   )
+)
+
+(for (set i 0) (=< i 10) (set i (+ i 1))
+   (assert
+      (= (access i sli0) (access i sli1) (- i 1))
+      [FAILED] (var test_name) Equality test safe 0.
+   )
+)
+
+(assert
+   (= (var sli0) (var sli1))
+   [FAILED] (var test_name) Equality test safe 0.
+)
 
 [COMPLETED] (var test_name)
 
diff --git a/src/core/src/tonkadur/fate/v1/error/UnknownSequenceException.java b/src/core/src/tonkadur/fate/v1/error/UnknownSequenceException.java
index bb12260..62c6744 100644
--- a/src/core/src/tonkadur/fate/v1/error/UnknownSequenceException.java
+++ b/src/core/src/tonkadur/fate/v1/error/UnknownSequenceException.java
@@ -1,6 +1,8 @@
 package tonkadur.fate.v1.error;
 
+import java.util.ArrayList;
 import java.util.Collection;
+import java.util.Collections;
 import java.util.List;
 
 import tonkadur.functional.Cons;
@@ -12,6 +14,8 @@ import tonkadur.parser.ParsingError;
 
 import tonkadur.fate.v1.lang.meta.Computation;
 
+import tonkadur.fate.v1.lang.computation.SequenceReference;
+
 public class UnknownSequenceException extends ParsingError
 {
    /***************************************************************************/
@@ -41,6 +45,32 @@ public class UnknownSequenceException extends ParsingError
       this.all_occurrences = all_occurrences;
    }
 
+   public UnknownSequenceException
+   (
+      final String sequence_name,
+      final Collection<SequenceReference> all_occurrences
+   )
+   {
+      super
+      (
+         ErrorLevel.ERROR,
+         ErrorCategory.UNKNOWN,
+         all_occurrences.iterator().next().get_origin()
+      );
+
+      this.sequence_name = sequence_name;
+
+      this.all_occurrences = new ArrayList<Cons<Origin, List<Computation>>>();
+
+      for (final SequenceReference occ: all_occurrences)
+      {
+         this.all_occurrences.add
+         (
+            new Cons(occ.get_origin(), Collections.singleton(occ))
+         );
+      }
+   }
+
    @Override
    public String toString ()
    {
diff --git a/src/core/src/tonkadur/fate/v1/lang/World.java b/src/core/src/tonkadur/fate/v1/lang/World.java
index c813312..d07d9b7 100644
--- a/src/core/src/tonkadur/fate/v1/lang/World.java
+++ b/src/core/src/tonkadur/fate/v1/lang/World.java
@@ -22,9 +22,13 @@ import tonkadur.fate.v1.lang.meta.Computation;
 import tonkadur.fate.v1.lang.meta.DeclarationCollection;
 import tonkadur.fate.v1.lang.meta.ExtensionInstruction;
 import tonkadur.fate.v1.lang.meta.ExtensionComputation;
+import tonkadur.fate.v1.lang.meta.RecurrentChecks;
 import tonkadur.fate.v1.lang.meta.Instruction;
 
 import tonkadur.fate.v1.lang.type.Type;
+import tonkadur.fate.v1.lang.type.SequenceType;
+
+import tonkadur.fate.v1.lang.computation.SequenceReference;
 
 public class World
 {
@@ -36,6 +40,7 @@ public class World
 
    protected final Map<String, List<Cons<Origin, List<Computation>>>>
       sequence_uses;
+   protected final Map<String, List<SequenceReference>> sequence_variables;
    protected final Map<String, ExtensionComputation> extension_value_nodes;
    protected final Map<String, ExtensionInstruction> extension_instructions;
    protected final Map<String, ExtensionInstruction>
@@ -63,6 +68,8 @@ public class World
       sequence_uses =
          new HashMap<String, List<Cons<Origin, List<Computation>>>>();
 
+      sequence_variables = new HashMap<String, List<SequenceReference>>();
+
       extension_value_nodes = new HashMap<String, ExtensionComputation>();
       extension_instructions = new HashMap<String, ExtensionInstruction>();
       extension_first_level_instructions =
@@ -141,6 +148,22 @@ public class World
       list_of_uses.add(new Cons(origin, parameters));
    }
 
+   public void add_sequence_variable (final SequenceReference sr)
+   {
+      List<SequenceReference> list_of_variables;
+
+      list_of_variables = sequence_variables.get(sr.get_sequence_name());
+
+      if (list_of_variables == null)
+      {
+         list_of_variables = new ArrayList<SequenceReference>();
+
+         sequence_variables.put(sr.get_sequence_name(), list_of_variables);
+      }
+
+      list_of_variables.add(sr);
+   }
+
    /**** Extension Stuff ****/
    public Map<String, ExtensionInstruction> extension_instructions ()
    {
@@ -209,6 +232,7 @@ public class World
       is_sane = true;
 
       is_sane = assert_sane_sequence_uses() & is_sane;
+      is_sane = assert_sane_sequence_variables() & is_sane;
 
       return is_sane;
    }
@@ -365,4 +389,74 @@ public class World
 
       return is_sane;
    }
+
+   protected boolean assert_sane_sequence_variables ()
+   throws Throwable
+   {
+      Sequence seq;
+
+      boolean is_sane;
+
+      is_sane = true;
+
+      for
+      (
+         final Map.Entry<String, List<SequenceReference>> entry:
+            sequence_variables.entrySet()
+      )
+      {
+         seq = sequences().get_or_null(entry.getKey());
+
+         if (seq == null)
+         {
+            final List<SequenceReference> variables;
+
+            variables = entry.getValue();
+
+            if (variables.isEmpty())
+            {
+               continue;
+            }
+
+            is_sane = false;
+
+            ErrorManager.handle
+            (
+               new UnknownSequenceException
+               (
+                  entry.getKey(),
+                  ((variables.size() == 1) ? null : variables)
+               )
+            );
+         }
+         else
+         {
+            final List<Type> signature_types;
+
+            signature_types = new ArrayList<Type>();
+
+            for (final Variable v: seq.get_signature())
+            {
+               signature_types.add(v.get_type());
+            }
+
+            for (final SequenceReference sr: entry.getValue())
+            {
+               ((SequenceType) sr.get_type()).propose_signature
+               (
+                  signature_types
+               );
+
+               RecurrentChecks.assert_types_matches_signature
+               (
+                  sr.get_origin(),
+                  ((SequenceType) sr.get_type()).get_signature(),
+                  signature_types
+               );
+            }
+         }
+      }
+
+      return is_sane;
+   }
 }
diff --git a/src/core/src/tonkadur/fate/v1/lang/computation/SequenceReference.java b/src/core/src/tonkadur/fate/v1/lang/computation/SequenceReference.java
new file mode 100644
index 0000000..f7984df
--- /dev/null
+++ b/src/core/src/tonkadur/fate/v1/lang/computation/SequenceReference.java
@@ -0,0 +1,63 @@
+package tonkadur.fate.v1.lang.computation;
+
+import tonkadur.parser.Origin;
+
+import tonkadur.fate.v1.lang.type.SequenceType;
+
+import tonkadur.fate.v1.lang.meta.ComputationVisitor;
+import tonkadur.fate.v1.lang.meta.Computation;
+
+public class SequenceReference extends Computation
+{
+   /***************************************************************************/
+   /**** MEMBERS **************************************************************/
+   /***************************************************************************/
+   protected final String sequence_name;
+
+   /***************************************************************************/
+   /**** PROTECTED ************************************************************/
+   /***************************************************************************/
+
+   /***************************************************************************/
+   /**** PUBLIC ***************************************************************/
+   /***************************************************************************/
+   /**** Constructors *********************************************************/
+   public SequenceReference
+   (
+      final Origin origin,
+      final String sequence_name
+   )
+   {
+      super(origin, new SequenceType(origin, "(seq " + sequence_name + ")"));
+
+      this.sequence_name = sequence_name;
+   }
+
+
+   /**** Accessors ************************************************************/
+   @Override
+   public void get_visited_by (final ComputationVisitor cv)
+   throws Throwable
+   {
+      cv.visit_sequence_reference(this);
+   }
+
+   public String get_sequence_name ()
+   {
+      return sequence_name;
+   }
+
+   /**** Misc. ****************************************************************/
+   @Override
+   public String toString ()
+   {
+      final StringBuilder sb = new StringBuilder();
+
+      sb.append("(SequenceReference ");
+      sb.append(sequence_name);
+
+      sb.append(")");
+
+      return sb.toString();
+   }
+}
diff --git a/src/core/src/tonkadur/fate/v1/lang/instruction/SequenceVariableCall.java b/src/core/src/tonkadur/fate/v1/lang/instruction/SequenceVariableCall.java
new file mode 100644
index 0000000..407f430
--- /dev/null
+++ b/src/core/src/tonkadur/fate/v1/lang/instruction/SequenceVariableCall.java
@@ -0,0 +1,125 @@
+package tonkadur.fate.v1.lang.instruction;
+
+import java.util.Collections;
+import java.util.List;
+
+import tonkadur.parser.Origin;
+import tonkadur.parser.ParsingError;
+
+import tonkadur.error.ErrorManager;
+
+import tonkadur.fate.v1.error.InvalidTypeException;
+
+import tonkadur.fate.v1.lang.type.SequenceType;
+import tonkadur.fate.v1.lang.type.Type;
+
+import tonkadur.fate.v1.lang.meta.Computation;
+import tonkadur.fate.v1.lang.meta.InstructionVisitor;
+import tonkadur.fate.v1.lang.meta.Instruction;
+import tonkadur.fate.v1.lang.meta.RecurrentChecks;
+
+public class SequenceVariableCall extends Instruction
+{
+   /***************************************************************************/
+   /**** MEMBERS **************************************************************/
+   /***************************************************************************/
+   protected final List<Computation> parameters;
+   protected final Computation sequence;
+
+   /***************************************************************************/
+   /**** PROTECTED ************************************************************/
+   /***************************************************************************/
+   /**** Constructors *********************************************************/
+   protected SequenceVariableCall
+   (
+      final Origin origin,
+      final Computation sequence,
+      final List<Computation> parameters
+   )
+   {
+      super(origin);
+
+      this.sequence = sequence;
+      this.parameters = parameters;
+   }
+
+   /***************************************************************************/
+   /**** PUBLIC ***************************************************************/
+   /***************************************************************************/
+   /**** Constructors *********************************************************/
+   public static SequenceVariableCall build
+   (
+      final Origin origin,
+      final Computation sequence,
+      final List<Computation> parameters
+   )
+   throws ParsingError
+   {
+      final List<Type> signature;
+
+      ((SequenceType) sequence.get_type()).propose_signature_from_parameters
+      (
+         parameters
+      );
+
+      if (!sequence.get_type().get_act_as_type().equals(Type.SEQUENCE))
+      {
+         ErrorManager.handle
+         (
+            new InvalidTypeException
+            (
+               origin,
+               sequence.get_type(),
+               Collections.singleton(Type.SEQUENCE)
+            )
+         );
+      }
+
+      RecurrentChecks.assert_computations_matches_signature
+      (
+         origin,
+         parameters,
+         ((SequenceType) sequence.get_type()).get_signature()
+      );
+
+      return new SequenceVariableCall(origin, sequence, parameters);
+   }
+
+   /**** Accessors ************************************************************/
+   @Override
+   public void get_visited_by (final InstructionVisitor iv)
+   throws Throwable
+   {
+      iv.visit_sequence_variable_call(this);
+   }
+
+   public Computation get_sequence ()
+   {
+      return sequence;
+   }
+
+   public List<Computation> get_parameters ()
+   {
+      return parameters;
+   }
+
+   /**** Misc. ****************************************************************/
+   @Override
+   public String toString ()
+   {
+      final StringBuilder sb = new StringBuilder();
+
+      sb.append("(SequenceVariableCall ");
+      sb.append(sequence);
+
+      for (final Computation c: parameters)
+      {
+         sb.append(" ");
+         sb.append(c.toString());
+      }
+
+      sb.append(")");
+
+      return sb.toString();
+   }
+}
diff --git a/src/core/src/tonkadur/fate/v1/lang/instruction/SequenceVariableJump.java b/src/core/src/tonkadur/fate/v1/lang/instruction/SequenceVariableJump.java
new file mode 100644
index 0000000..52aa947
--- /dev/null
+++ b/src/core/src/tonkadur/fate/v1/lang/instruction/SequenceVariableJump.java
@@ -0,0 +1,125 @@
+package tonkadur.fate.v1.lang.instruction;
+
+import java.util.Collections;
+import java.util.List;
+
+import tonkadur.parser.Origin;
+import tonkadur.parser.ParsingError;
+
+import tonkadur.error.ErrorManager;
+
+import tonkadur.fate.v1.error.InvalidTypeException;
+
+import tonkadur.fate.v1.lang.type.SequenceType;
+import tonkadur.fate.v1.lang.type.Type;
+
+import tonkadur.fate.v1.lang.meta.Computation;
+import tonkadur.fate.v1.lang.meta.InstructionVisitor;
+import tonkadur.fate.v1.lang.meta.Instruction;
+import tonkadur.fate.v1.lang.meta.RecurrentChecks;
+
+public class SequenceVariableJump extends Instruction
+{
+   /***************************************************************************/
+   /**** MEMBERS **************************************************************/
+   /***************************************************************************/
+   protected final List<Computation> parameters;
+   protected final Computation sequence;
+
+   /***************************************************************************/
+   /**** PROTECTED ************************************************************/
+   /***************************************************************************/
+   /**** Constructors *********************************************************/
+   protected SequenceVariableJump
+   (
+      final Origin origin,
+      final Computation sequence,
+      final List<Computation> parameters
+   )
+   {
+      super(origin);
+
+      this.sequence = sequence;
+      this.parameters = parameters;
+   }
+
+   /***************************************************************************/
+   /**** PUBLIC ***************************************************************/
+   /***************************************************************************/
+   /**** Constructors *********************************************************/
+   public static SequenceVariableJump build
+   (
+      final Origin origin,
+      final Computation sequence,
+      final List<Computation> parameters
+   )
+   throws ParsingError
+   {
+      final List<Type> signature;
+
+      ((SequenceType) sequence.get_type()).propose_signature_from_parameters
+      (
+         parameters
+      );
+
+      if (!sequence.get_type().get_act_as_type().equals(Type.SEQUENCE))
+      {
+         ErrorManager.handle
+         (
+            new InvalidTypeException
+            (
+               origin,
+               sequence.get_type(),
+               Collections.singleton(Type.SEQUENCE)
+            )
+         );
+      }
+
+      RecurrentChecks.assert_computations_matches_signature
+      (
+         origin,
+         parameters,
+         ((SequenceType) sequence.get_type()).get_signature()
+      );
+
+      return new SequenceVariableJump(origin, sequence, parameters);
+   }
+
+   /**** Accessors ************************************************************/
+   @Override
+   public void get_visited_by (final InstructionVisitor iv)
+   throws Throwable
+   {
+      iv.visit_sequence_variable_jump(this);
+   }
+
+   public Computation get_sequence ()
+   {
+      return sequence;
+   }
+
+   public List<Computation> get_parameters ()
+   {
+      return parameters;
+   }
+
+   /**** Misc. ****************************************************************/
+   @Override
+   public String toString ()
+   {
+      final StringBuilder sb = new StringBuilder();
+
+      sb.append("(SequenceVariableJump ");
+      sb.append(sequence);
+
+      for (final Computation c: parameters)
+      {
+         sb.append(" ");
+         sb.append(c.toString());
+      }
+
+      sb.append(")");
+
+      return sb.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 4631a2f..adb3a05 100644
--- a/src/core/src/tonkadur/fate/v1/lang/meta/ComputationVisitor.java
+++ b/src/core/src/tonkadur/fate/v1/lang/meta/ComputationVisitor.java
@@ -79,6 +79,9 @@ public interface ComputationVisitor
    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;
 
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 a672f3c..406cd7f 100644
--- a/src/core/src/tonkadur/fate/v1/lang/meta/InstructionVisitor.java
+++ b/src/core/src/tonkadur/fate/v1/lang/meta/InstructionVisitor.java
@@ -140,6 +140,12 @@ public interface InstructionVisitor
    public void visit_sequence_jump (final SequenceJump n)
    throws Throwable;
 
+   public void visit_sequence_variable_call (final SequenceVariableCall n)
+   throws Throwable;
+
+   public void visit_sequence_variable_jump (final SequenceVariableJump n)
+   throws Throwable;
+
    public void visit_local_variable (final LocalVariable n)
    throws Throwable;
 
diff --git a/src/core/src/tonkadur/fate/v1/lang/type/SequenceType.java b/src/core/src/tonkadur/fate/v1/lang/type/SequenceType.java
new file mode 100644
index 0000000..c6e7ef3
--- /dev/null
+++ b/src/core/src/tonkadur/fate/v1/lang/type/SequenceType.java
@@ -0,0 +1,193 @@
+package tonkadur.fate.v1.lang.type;
+
+import java.util.ArrayList;
+import java.util.Iterator;
+import java.util.List;
+
+import tonkadur.parser.Origin;
+
+import tonkadur.fate.v1.lang.meta.DeclaredEntity;
+import tonkadur.fate.v1.lang.meta.Computation;
+
+public class SequenceType extends Type
+{
+   /***************************************************************************/
+   /**** MEMBERS **************************************************************/
+   /***************************************************************************/
+   protected final List<Type> signature;
+   protected boolean signature_is_defined;
+
+   /***************************************************************************/
+   /**** PUBLIC ***************************************************************/
+   /***************************************************************************/
+
+   /**** Constructors *********************************************************/
+   public SequenceType
+   (
+      final Origin origin,
+      final String name,
+      final List<Type> signature
+   )
+   {
+      super(origin, null, name);
+
+      this.signature = signature;
+      this.signature_is_defined = true;
+   }
+
+   public SequenceType
+   (
+      final Origin origin,
+      final String name
+   )
+   {
+      super(origin, null, name);
+
+      this.signature = new ArrayList<Type>();
+      this.signature_is_defined = false;
+   }
+
+   /**** Accessors ************************************************************/
+   public List<Type> get_signature ()
+   {
+      return signature;
+   }
+
+   public void propose_signature (final List<Type> signature)
+   {
+      if (signature_is_defined)
+      {
+         return;
+      }
+
+      this.signature.addAll(signature);
+
+      signature_is_defined = true;
+   }
+
+   public void propose_signature_from_parameters
+   (
+      final List<Computation> params
+   )
+   {
+      if (signature_is_defined)
+      {
+         return;
+      }
+
+      for (final Computation c: params)
+      {
+         signature.add(c.get_type());
+      }
+
+      signature_is_defined = true;
+   }
+
+   /**** Compatibility ********************************************************/
+   @Override
+   public boolean can_be_used_as (final Type t)
+   {
+      if (t instanceof SequenceType)
+      {
+         final Iterator<Type> i0, i1;
+         final SequenceType lt;
+
+         lt = (SequenceType) t;
+
+         propose_signature(lt.get_signature());
+
+         if (signature.size() != lt.signature.size())
+         {
+            return false;
+         }
+
+         i0 = signature.iterator();
+         i1 = lt.signature.iterator();
+
+         while(i0.hasNext())
+         {
+            if (!i0.next().can_be_used_as(i1.next()))
+            {
+               return false;
+            }
+         }
+
+         return true;
+      }
+
+      return false;
+   }
+
+   /*
+    * This is for the very special case where a type is used despite not being
+    * even a sub-type of the expected one. Using this rather expensive function,
+    * the most restrictive shared type will be returned. If no such type exists,
+    * the ANY time is returned.
+    */
+   @Override
+   public DeclaredEntity generate_comparable_to (final DeclaredEntity de)
+   {
+      final Iterator<Type> i0, i1;
+      final List<Type> resulting_signature;
+      final SequenceType lt;
+
+      if (!(de instanceof SequenceType))
+      {
+         return Type.ANY;
+      }
+
+      lt = (SequenceType) de;
+
+      if (lt.signature.size() != signature.size())
+      {
+         return Type.ANY;
+      }
+
+      resulting_signature = new ArrayList<Type>();
+
+      i0 = signature.iterator();
+      i1 = lt.signature.iterator();
+
+      while(i0.hasNext())
+      {
+         resulting_signature.add
+         (
+            (Type) i0.next().generate_comparable_to(i1.next())
+         );
+      }
+
+      return new SequenceType(get_origin(), name, resulting_signature);
+   }
+
+   @Override
+   public Type get_act_as_type ()
+   {
+      return Type.SEQUENCE;
+   }
+
+   /**** Misc. ****************************************************************/
+   @Override
+   public Type generate_alias (final Origin origin, final String name)
+   {
+      return new SequenceType(origin, name, signature);
+   }
+
+   @Override
+   public String toString ()
+   {
+      final StringBuilder sb = new StringBuilder();
+
+      sb.append("(Sequence (");
+
+      for (final Type t: signature)
+      {
+         sb.append(t.get_name());
+         sb.append(" ");
+      }
+
+      sb.append("))::");
+      sb.append(name);
+
+      return sb.toString();
+   }
+}
diff --git a/src/core/src/tonkadur/fate/v1/lang/type/Type.java b/src/core/src/tonkadur/fate/v1/lang/type/Type.java
index ac4bcb3..ce93e9e 100644
--- a/src/core/src/tonkadur/fate/v1/lang/type/Type.java
+++ b/src/core/src/tonkadur/fate/v1/lang/type/Type.java
@@ -29,6 +29,7 @@ public class Type extends DeclaredEntity
    public static final Type LIST;
    public static final Type REF;
    public static final Type RICH_TEXT;
+   public static final Type SEQUENCE;
    public static final Type SET;
    public static final Type STRING;
 
@@ -57,6 +58,7 @@ public class Type extends DeclaredEntity
       LIST = new Type(base, null, "list");
       REF = new Type(base, null, "ref");
       RICH_TEXT = new Type(base, null, "text");
+      SEQUENCE = new Type(base, null, "sequence");
       SET = new Type(base, null, "set");
       STRING = new Type(base, null, "string");
 
@@ -71,6 +73,7 @@ public class Type extends DeclaredEntity
       ALL_TYPES.add(LIST);
       ALL_TYPES.add(REF);
       ALL_TYPES.add(RICH_TEXT);
+      ALL_TYPES.add(SEQUENCE);
       ALL_TYPES.add(SET);
       ALL_TYPES.add(STRING);
 
@@ -83,6 +86,7 @@ public class Type extends DeclaredEntity
 
       COMPARABLE_TYPES.add(FLOAT);
       COMPARABLE_TYPES.add(INT);
+      COMPARABLE_TYPES.add(SEQUENCE);
       COMPARABLE_TYPES.add(LAMBDA);
       COMPARABLE_TYPES.add(STRING);
       COMPARABLE_TYPES.add(BOOL);
diff --git a/src/core/src/tonkadur/fate/v1/parser/FateLexer.g4 b/src/core/src/tonkadur/fate/v1/parser/FateLexer.g4
index b7b64dd..4b6edfc 100644
--- a/src/core/src/tonkadur/fate/v1/parser/FateLexer.g4
+++ b/src/core/src/tonkadur/fate/v1/parser/FateLexer.g4
@@ -154,6 +154,7 @@ SUB_LIST_KW: L_PAREN 'sub'US'list' SEP+;
 IMP_SUB_LIST_KW: L_PAREN 'sub'US'list!' SEP+;
 LIST_KW: L_PAREN 'list' SEP+;
 SIZE_KW: L_PAREN 'size' SEP+;
+SEQUENCE_KW: L_PAREN ('seq'|'sequence') SEP+;
 SWITCH_KW: L_PAREN 'switch' SEP+;
 TIMES_KW: L_PAREN ('times'|'*') SEP+;
 TRUE_KW: L_PAREN 'true)';
diff --git a/src/core/src/tonkadur/fate/v1/parser/FateParser.g4 b/src/core/src/tonkadur/fate/v1/parser/FateParser.g4
index 16a9472..8465af6 100644
--- a/src/core/src/tonkadur/fate/v1/parser/FateParser.g4
+++ b/src/core/src/tonkadur/fate/v1/parser/FateParser.g4
@@ -1801,6 +1801,86 @@ returns [Instruction result]
       $result = new SequenceJump(origin, sequence_name, params);
    }
 
+   | VISIT_KW value WS+ value_list WS* R_PAREN
+   {
+      final Origin origin;
+
+      origin =
+         CONTEXT.get_origin_at
+         (
+            ($VISIT_KW.getLine()),
+            ($VISIT_KW.getCharPositionInLine())
+         );
+
+      $result =
+         SequenceVariableCall.build
+         (
+            origin,
+            ($value.result),
+            ($value_list.result)
+         );
+   }
+
+   | VISIT_KW value WS* R_PAREN
+   {
+      final Origin origin;
+
+      origin =
+         CONTEXT.get_origin_at
+         (
+            ($VISIT_KW.getLine()),
+            ($VISIT_KW.getCharPositionInLine())
+         );
+
+      $result =
+         SequenceVariableCall.build
+         (
+            origin,
+            ($value.result),
+            new ArrayList<Computation>()
+         );
+   }
+
+   | CONTINUE_AS_KW value WS+ value_list WS* R_PAREN
+   {
+      final Origin origin;
+
+      origin =
+         CONTEXT.get_origin_at
+         (
+            ($CONTINUE_AS_KW.getLine()),
+            ($CONTINUE_AS_KW.getCharPositionInLine())
+         );
+
+      $result =
+         SequenceVariableJump.build
+         (
+            origin,
+            ($value.result),
+            ($value_list.result)
+         );
+   }
+
+   | CONTINUE_AS_KW value WS* R_PAREN
+   {
+      final Origin origin;
+
+      origin =
+         CONTEXT.get_origin_at
+         (
+            ($CONTINUE_AS_KW.getLine()),
+            ($CONTINUE_AS_KW.getCharPositionInLine())
+         );
+
+      $result =
+         SequenceVariableJump.build
+         (
+            origin,
+            ($value.result),
+            new ArrayList<Computation>()
+         );
+   }
+
    | ASSERT_KW non_text_value WS+ paragraph WS* R_PAREN
    {
       $result =
@@ -2798,6 +2878,26 @@ returns [Type result]
             ($type_list.result)
          );
    }
+
+   | SEQUENCE_KW type_list WS* R_PAREN
+   {
+      final Origin start_origin;
+
+      start_origin =
+         CONTEXT.get_origin_at
+         (
+            ($SEQUENCE_KW.getLine()),
+            ($SEQUENCE_KW.getCharPositionInLine())
+         );
+
+      $result =
+         new SequenceType
+         (
+            start_origin,
+            "auto_generated",
+            ($type_list.result)
+         );
+   }
 ;
 catch [final Throwable e]
 {
@@ -4092,6 +4192,24 @@ returns [Computation result]
       }
    }
 
+   | SEQUENCE_KW WORD WS* R_PAREN
+   {
+      final SequenceReference sr;
+      final Origin origin;
+
+      origin =
+         CONTEXT.get_origin_at
+         (
+            ($SEQUENCE_KW.getLine()),
+            ($SEQUENCE_KW.getCharPositionInLine())
+         );
+
+      sr = new SequenceReference(origin, ($WORD.text));
+      $result = sr;
+
+      WORLD.add_sequence_variable(sr);
+   }
+
    | EVAL_KW value_reference WS* R_PAREN
    {
       final Origin origin;
diff --git a/src/core/src/tonkadur/wyrd/v1/compiler/fate/v1/ComputationCompiler.java b/src/core/src/tonkadur/wyrd/v1/compiler/fate/v1/ComputationCompiler.java
index 2df0868..110c670 100644
--- a/src/core/src/tonkadur/wyrd/v1/compiler/fate/v1/ComputationCompiler.java
+++ b/src/core/src/tonkadur/wyrd/v1/compiler/fate/v1/ComputationCompiler.java
@@ -3955,4 +3955,18 @@ implements tonkadur.fate.v1.lang.meta.ComputationVisitor
          cc.release_registers(init_instructions);
       }
    }
+
+   @Override
+   public void visit_sequence_reference
+   (
+      final tonkadur.fate.v1.lang.computation.SequenceReference n
+   )
+   throws Throwable
+   {
+      result_as_computation =
+         compiler.assembler().get_label_constant
+         (
+            n.get_sequence_name()
+         );
+   }
 }
diff --git a/src/core/src/tonkadur/wyrd/v1/compiler/fate/v1/InstructionCompiler.java b/src/core/src/tonkadur/wyrd/v1/compiler/fate/v1/InstructionCompiler.java
index 5986682..dda6d2e 100644
--- a/src/core/src/tonkadur/wyrd/v1/compiler/fate/v1/InstructionCompiler.java
+++ b/src/core/src/tonkadur/wyrd/v1/compiler/fate/v1/InstructionCompiler.java
@@ -3514,6 +3514,79 @@ implements tonkadur.fate.v1.lang.meta.InstructionVisitor
    }
 
    @Override
+   public void visit_sequence_variable_call
+   (
+      final tonkadur.fate.v1.lang.instruction.SequenceVariableCall n
+   )
+   throws Throwable
+   {
+      final ComputationCompiler sequence_cc;
+      final List<ComputationCompiler> parameter_ccs;
+      final List<Computation> parameters;
+
+      final String return_to_label;
+
+      return_to_label =
+         compiler.assembler().generate_label("<seq_call#return_to>");
+
+      sequence_cc = new ComputationCompiler(compiler);
+      parameter_ccs = new ArrayList<ComputationCompiler>();
+      parameters = new ArrayList<Computation>();
+
+      n.get_sequence().get_visited_by(sequence_cc);
+
+      if (sequence_cc.has_init())
+      {
+         result.add(sequence_cc.get_init());
+      }
+
+      for
+      (
+         final tonkadur.fate.v1.lang.meta.Computation param: n.get_parameters()
+      )
+      {
+         final ComputationCompiler cc;
+
+         cc = new ComputationCompiler(compiler);
+
+         param.get_visited_by(cc);
+
+         if (cc.has_init())
+         {
+            result.add(cc.get_init());
+         }
+
+         parameters.add(cc.get_computation());
+         parameter_ccs.add(cc);
+      }
+
+      result.addAll(compiler.registers().store_parameters(parameters));
+
+      result.add
+      (
+         compiler.assembler().mark_after
+         (
+            compiler.assembler().merge
+            (
+               compiler.registers().get_visit_context_instructions
+               (
+                  sequence_cc.get_computation(),
+                  compiler.assembler().get_label_constant(return_to_label)
+               )
+            ),
+            return_to_label
+         )
+      );
+
+      sequence_cc.release_registers(result);
+
+      for (final ComputationCompiler cc: parameter_ccs)
+      {
+         cc.release_registers(result);
+      }
+   }
+
+   @Override
    public void visit_sequence_jump
    (
       final tonkadur.fate.v1.lang.instruction.SequenceJump n
@@ -3574,6 +3647,72 @@ implements tonkadur.fate.v1.lang.meta.InstructionVisitor
    }
 
    @Override
+   public void visit_sequence_variable_jump
+   (
+      final tonkadur.fate.v1.lang.instruction.SequenceVariableJump n
+   )
+   throws Throwable
+   {
+      final ComputationCompiler sequence_cc;
+      final List<ComputationCompiler> parameter_ccs;
+      final List<Computation> parameters;
+
+      sequence_cc = new ComputationCompiler(compiler);
+      parameter_ccs = new ArrayList<ComputationCompiler>();
+      parameters = new ArrayList<Computation>();
+
+      n.get_sequence().get_visited_by(sequence_cc);
+
+      if (sequence_cc.has_init())
+      {
+         result.add(sequence_cc.get_init());
+      }
+
+      for
+      (
+         final tonkadur.fate.v1.lang.meta.Computation param: n.get_parameters()
+      )
+      {
+         final ComputationCompiler cc;
+
+         cc = new ComputationCompiler(compiler);
+
+         param.get_visited_by(cc);
+
+         if (cc.has_init())
+         {
+            result.add(cc.get_init());
+         }
+
+         parameters.add(cc.get_computation());
+         parameter_ccs.add(cc);
+      }
+
+      result.addAll(compiler.registers().store_parameters(parameters));
+
+      for (final ComputationCompiler cc: parameter_ccs)
+      {
+         cc.release_registers(result);
+      }
+
+      /* Terminate current context */
+      result.addAll
+      (
+         compiler.registers().get_finalize_context_instructions()
+      );
+
+      result.addAll
+      (
+         compiler.registers().get_jump_to_context_instructions
+         (
+            sequence_cc.get_computation()
+         )
+      );
+
+      sequence_cc.release_registers(result);
+   }
+
+   @Override
    public void visit_set_value
    (
       final tonkadur.fate.v1.lang.instruction.SetValue n
diff --git a/src/core/src/tonkadur/wyrd/v1/compiler/fate/v1/TypeCompiler.java b/src/core/src/tonkadur/wyrd/v1/compiler/fate/v1/TypeCompiler.java
index f820d7b..af4f703 100644
--- a/src/core/src/tonkadur/wyrd/v1/compiler/fate/v1/TypeCompiler.java
+++ b/src/core/src/tonkadur/wyrd/v1/compiler/fate/v1/TypeCompiler.java
@@ -68,6 +68,11 @@ public class TypeCompiler
          return Type.INT;
       }
 
+      if (fate_type instanceof tonkadur.fate.v1.lang.type.SequenceType)
+      {
+         return Type.INT;
+      }
+
       fate_type = fate_type.get_base_type();
 
       if (fate_type.equals(tonkadur.fate.v1.lang.type.Type.BOOL))
@@ -181,6 +186,11 @@ public class TypeCompiler
          return MapType.MAP_TO_INT;
       }
 
+      if (fate_content_type instanceof tonkadur.fate.v1.lang.type.SequenceType)
+      {
+         return MapType.MAP_TO_INT;
+      }
+
       return new MapType(compile(compiler, fate_content_type));
    }
 }