#lang scribble/manual
@(require (for-label racket
                     "main.rkt"))
@(require "main.rkt"
          planet/scribble)

@title{Structured Loops}

@(defmodule/this-package main)
@defform*[#:literals (or then)
          [(until condition
             body
             ...)
           (until (or (alternative-condition then
                                             result
                                             ...)
                      ...)
             body
             ...)]]{                   
First form: check @racket[condition], repeating @racket[body] until the condition is true,
 i.e. while it's false. The result is the value of @racket[condition].
      
Second form: the disjunction of the @racket[alternative-condition]s
 is used as the condition --- i.e. loop until at least one of the @racket[alternative-condition]s is true.
 The result is the value of the (first one's) corresponding @racket[result ...] .
}
@defform*[#:literals (and else)
          [(while condition
             body
             ...)
           (while (and (sub-condition else
                                      result
                                      ...)
                       ...)
             body
             ...)]]{
First form: check @racket[condition], repeating @racket[body] while the condition is true,
 i.e. until it's false. The result is false.
      
Second form: the conjunction of the @racket[sub-condition]s is used as the condition
 --- i.e. loop until at least one of the @racket[alternative-condition]s is false.
 The result is the value of the (first one's) corresponding @racket[result ...].
}
@deftogether[[(defproc (continue) any)
              (defproc (break (v any void)) any)]]{Within the body of an @racket[until] or @racket[while] form,
                                                        calling @racket[continue] ends the current iteration
                                                        and tries (by checking the condition first) the next iteration.
                                                        Calling @racket[break] ends the loop using @racket[v] as the loop's result
                                                        (defaulting to @void-const).
                                                        
                                                        Use outside the body of an @racket[until] or @racket[while] form is a syntax error.}