for

for is Coalton’s built-in imperative loop form.

Syntax

(for (⟨binding-clause⟩...)
  [:returns ⟨expr⟩]
  [{:while | :until | :repeat} ⟨expr⟩]
  ⟨body⟩...)

;; ⟨binding-clause⟩ := (⟨var⟩ ⟨init-expr⟩ ⟨step-expr⟩)

Semantics

• Initializers are established before the first iteration.
• Step expressions are evaluated in parallel from the previous iteration’s bindings.
• :while loops while the condition is true.
• :until loops until the condition is true.
• :repeat loops a certain fixed number of times.
• :returns specifies what to return when the loop exits, either normally or by (break).
• No :returns means the loop unifies with Void.
• Use for* when later steps should see earlier updated values.

Example

(for ((i 0 (1+ i)))
  :until (>= i 10)
  (show i))