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+---
+menuTitle: Loops
+title: "Doing Things Over and Over"
+weight: 11
+---
+[The previous step](/learn/conditions) introduced conditions, making it
+possible to change the flow of execution according to the value of variables.
+In this step, we look at loops, which will make instructions be executed a
+certain number time depending on a condition, or just for each element of a
+collection.
+
+Fate offers the following loop constructs:
+* `while`, to execute instructions if and as many time as a condition is
+   verified.
+* `do_while`, to execute instructions at least once, then as many time as a
+   condition is verified.
+* `for`, a loop that has pre-instructions, a condition to verify before each
+   execution of the main body, the main body of instructions itself, then
+   post-instructions, which are executed before checking the condition.
+* `for_each`, a loop that executes for each member of a collection.
+
+The `for_each` loops can also be used within a `player_choice!` to control what
+options are available.
+
+Let's change how armors and weapons are displayed to the player:
+
+**smithy.fate:**
+{{< fatecode >}}(fate_version 1)
+(require smithy_inventory.fate)
+
+;; Maybe it would be better to put this in a different file, but oh well...
+(global (lambda text ((cons #weapon int))) get_weapon_offer_label)
+(global (lambda text ((cons #armor int))) get_armor_offer_label)
+
+(set! get_weapon_offer_label
+   (lambda
+      ( ((cons #weapon int) offer) )
+      (let
+         (
+            (weapon (car offer))
+            (price (cdr offer))
+         )
+         (text
+            Buy "(var weapon.name)" (lp)attack: (var weapon.attack),
+            precision: (var weapon.precision)(rp) for (var price) coins.
+         )
+      )
+   )
+)
+
+(set! get_armor_offer_label
+   (lambda
+      ( ((cons #armor int) offer) )
+      (let
+         (
+            (armor (car offer))
+            (price (cdr offer))
+         )
+         (text
+            Buy "(var armor.name)" (lp)defense: (var armor.defense)(rp),
+            for (var price) coins.
+         )
+      )
+   )
+)
+
+(global bool has_visited_smithy (false))
+
+(define_sequence visit_smithy ()
+   (if (not has_visited_smithy)
+      As you approach the smithy, you notice that no one's there. All the wares
+      are out for selling. It's almost as if this story didn't need more
+      examples of lengthy dialogues.
+      (newline)
+      (set! has_visited_smithy (true))
+   )
+   You have (var hero.money) coins.
+   (newline)
+   What will you look at?
+   (player_choice!
+      (option ( Let's see the weapons )
+         (jump_to! see_weapons)
+      )
+      (option ( Let's see the armors )
+         (jump_to! see_armors)
+      )
+      (option ( Nothing, let's go back to the bar )
+      )
+   )
+)
+
+(define_sequence see_weapons ()
+   (player_choice!
+      (foreach smithy_weapons weapon
+         (option ( (eval get_weapon_offer_label weapon) )
+            (visit! buy_weapon weapon)
+         )
+      )
+      (option ( Nevermind ) )
+   )
+   (jump_to! visit_smithy)
+)
+
+(define_sequence see_armors ()
+   ;; Not as good as a for_each in this case, but let's use a for to show how
+   ;; it can be done.
+
+   (player_choice!
+      (for
+         ( (i 0) )
+         (< i (list:size smithy_armors))
+         ( (i (+ i 1)) )
+
+         (option ( (eval get_armor_offer_label (list:access i smithy_armors)) )
+            (visit! buy_armor (list:access i smithy_armors))
+         )
+      )
+      (option ( Nevermind ) )
+   )
+   (jump_to! visit_smithy)
+)
+
+(define_sequence buy_weapon ( ((cons #weapon int) weapon) )
+   (local int money_after)
+
+   (set! money_after (- hero.money (cdr weapon)))
+
+   (if_else (< money_after 0)
+      (
+         You can't afford that.
+         (newline)
+         You would need (abs money_after) more coins.
+      )
+      (
+         (set! hero.weapon (car weapon))
+         (set! hero.money money_after)
+         Equipped (var hero.weapon.name).
+      )
+   )
+   (newline)
+)
+
+(define_sequence buy_armor ( ((cons #armor int) armor) )
+   (local int money_after)
+
+   (set! money_after (- hero.money (cdr armor)))
+
+   (if_else (< money_after 0)
+      (
+         You can't afford that.
+         (newline)
+         You would need (abs money_after) more coins.
+      )
+      (
+         (set! hero.armor (car armor))
+         (set! hero.money money_after)
+         Equipped (var hero.armor.name).
+      )
+   )
+   (newline)
+)
+{{< /fatecode >}}
+
+Let's also look at a loop not within a `player_choice!` construct. We'll have
+the player try to count sheeps:
+
+**falling_asleep.fate:**
+{{< fatecode >}}(fate_version 1)
+(require data.fate)
+
+(global (list string) affirmative_messages)
+
+(list:add!
+   Indeed.
+   (string Sounds about right.)
+   Yes.
+   Agreed.
+   (string That's correct.)
+   True.
+   Undoubtedly.
+   Certainly.
+   (string Without a doubt.)
+   Correct.
+   Affirmative.
+   affirmative_messages
+)
+
+(global (lambda string ()) get_affirmative_message
+   (lambda ()
+      (list:access
+         (rand 0 (- (list:size affirmative_messages) 1))
+         affirmative_messages
+      )
+   )
+)
+
+(define_sequence count_sheeps ()
+   (local int sheeps 0)
+
+   You start imagining some pasture with no sheeps.
+
+   (while (< sheeps 100)
+      (local int player_guess)
+      (local int new_sheeps (rand 1 20))
+
+      (if_else (= new_sheeps 1)
+         ( A single sheep appears. )
+         ( (var new_sheeps) sheeps appear. )
+      )
+
+      (set! sheeps (+ sheeps new_sheeps))
+
+      (prompt_integer! (ptr player_guess) 0 120 How many sheeps are there now?)
+
+      (if_else (= sheeps player_guess)
+         (eval get_affirmative_message)
+         (
+            No. It was (var sheeps), you're pretty sure. The doubt wakes you up.
+            (newline)
+            (break!)
+         )
+      )
+      (newline)
+   )
+)
+
+(define_sequence fall_asleep ()
+   Deciding to break away from the expected storyline, you attempt to fall
+   asleep. It's not easy, though. Maybe counting sheeps would help?
+
+   (visit! count_sheeps)
+   (newline)
+   Upon waking up, your hard-trained reflexes inform you that someone stole all
+   your money.
+   (set! hero.money 0)
+   (newline)
+   This set-back was more than you could handle. You give up on this barely
+   coherent story.
+   (end!)
+)
+{{< /fatecode >}}
+
+[The next step of this tutorial](/learn/going_deeper) goes deeper into all the
+concepts that were already explored.
+
+----
+
+## Unchanged Files
+
+**data.fate:**
+{{< fatecode >}}(fate_version 1)
+
+(declare_structure #weapon
+   (text name)
+   (int attack)
+   (int precision)
+)
+
+(declare_structure #armor
+   (text name)
+   (int defense)
+)
+
+(declare_structure #character
+   (string name)
+   (int money)
+   (#weapon weapon)
+   (#armor armor)
+)
+
+(global #character hero)
+
+(struct:set_fields! hero.weapon
+   (name (text "Legendary" sword))
+   (attack 3)
+   (precision 50)
+)
+
+(struct:set_fields! hero.armor
+   (name (text "Refined" attire))
+   (defense 1)
+)
+
+(set! hero.money 200)
+
+{{< /fatecode >}}
+
+**get_a_refill.fate:**
+{{< fatecode >}}(fate_version 1)
+
+(require data.fate)
+(require actions.fate)
+(require smithy.fate)
+
+(define_sequence lower_price_of_booze
+   (
+      ((ptr int) price_pointer)
+      (int decrease)
+   )
+   Great! The price of booze just lowered from (at price_pointer)
+   (set! (at price_pointer)
+      (- (at price_pointer) decrease)
+   )
+   to (at price_pointer)!
+)
+
+(define_sequence get_a_refill ()
+   (local int price_of_booze)
+
+   (set! price_of_booze 12)
+
+   Staring straight at the barman, you raise your glass and proclaim:
+   (newline)
+   "This soon-to-be world savior needs more booze!"
+   (newline)
+   The barman's lack of reaction is disappointing, but seeing the beer being
+   poured does improve your mood.
+   (newline)
+   Satisfied, you hand the barman (var price_of_booze) copper coins.
+   (visit! pay price_of_booze)
+   The barman sighs, then asks:
+   (prompt_string! (ptr hero.name) 2 64 What is your name, then, hero?)
+   "(var hero.name)?"
+   (newline)
+   (switch hero.name
+      (Fred
+         You brace for the inevitable mockery.
+      )
+      (Link
+         You show the back of your hand to the barman.
+      )
+      ((string Lancelot of Camelot)
+         You place halves of a coconut shell on the bar.
+      )
+      The barman looks surprised.
+   )
+   (newline)
+   (visit! lower_price_of_booze (ptr price_of_booze) 4)
+   (newline)
+   "I have heard of you, (var hero.name)," the barman exclaims, "I have a quest
+   for you!"
+   (newline)
+   It's your turn to sigh.
+   (newline)
+   The barman hands you a bag, and says:
+   (newline)
+   "Take this pre-payment and head to the smithy."
+   (newline)
+   (visit! visit_smithy)
+)
+{{< /fatecode >}}
+
+**actions.fate:**
+{{< fatecode >}}(fate_version 1)
+
+(require data.fate)
+
+(define_sequence pay ( (int cost) )
+   (set! hero.money (- hero.money cost))
+)
+{{< /fatecode >}}
+
+**main.fate:**
+{{< fatecode >}}(fate_version 1)
+
+(require get_a_refill.fate)
+(require falling_asleep.fate)
+
+Once upon a time, starting a story with these words wasn't considered a cliche.
+Starting in a tavern might also not be seen as very original.  Having the main
+character be an street orphan, raised by some mysterious sage all to end up as
+a mercenary with an uncommonly strong sense of honor probably isn't going to
+lead to any praises for novelty either. Maybe you should drink to that.
+(newline)
+Or maybe you shouldn't. This isn't your first mug. Not your second either.
+Drinking to forget that you are a stereotypical hero isn't going to solve
+anything. Worse, the alcoholic trait is part of the image.
+(newline)
+As you contemplate your own pointless description, your gaze leaves what turns
+out to be an already empty glass in your hand and finds the barman.
+
+(player_choice!
+   (option ( Ask the barman for a refill )
+      (visit! get_a_refill)
+   )
+   (option ( Fall asleep )
+      (jump_to! fall_asleep)
+   )
+)
+
+;; Let's analyze how well the player did
+(cond
+   ((> hero.weapon.attack 7)
+      Your feel ready to strike down any challenge.
+   )
+   ((>= hero.armor.defense 7)
+      Your feel invincible.
+   )
+   ((>= hero.money 50)
+      You feel good about having spent your coins sparingly.
+   )
+   ((true)
+      You feel like you wasted your evening.
+   )
+)
+(end!)
+{{< /fatecode >}}
+
+**smithy_inventory.fate:**
+{{< fatecode >}}(fate_version 1)
+
+(require data.fate)
+
+(global (list (cons #weapon int)) smithy_weapons)
+(global (list (cons #armor int)) smithy_armors)
+
+(list:add!
+   (cons
+      (struct:set_fields (default #weapon)
+         (name (text An Iron Rod))
+         (attack 10)
+         (precision 70)
+      )
+      176
+   )
+   smithy_weapons
+)
+(list:add!
+   (cons
+      (struct:set_fields (default #weapon)
+         (name (text A Magnificient Brick))
+         (attack 6)
+         (precision 90)
+      )
+      110
+   )
+   smithy_weapons
+)
+
+(list:add!
+   (cons
+      (struct:set_fields (default #armor)
+         (name (text A raincoat?!))
+         (defense 7)
+      )
+      160
+   )
+   (cons
+      (struct:set_fields (default #armor)
+         (name (text A nice cape))
+         (defense 3)
+      )
+      50
+   )
+   smithy_armors
+)
+{{< /fatecode >}}