37 lines
944 B
Racket
37 lines
944 B
Racket
#lang scribble/doc
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@(require "mz.rkt" scribble/eval (for-label racket/block))
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@(define ev (make-base-eval))
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@(ev '(require racket/block))
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@title[#:tag "block"]{Blocks: @racket[block]}
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@note-lib-only[racket/block]
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@defform[(block defn-or-expr ...)]{
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Supports a mixture of expressions and mutually recursive definitions,
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as in a @racket[module] body. Unlike an @tech{internal-definition
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context}, the last @racket[defn-or-expr] need not be an expression.
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The result of the @racket[block] form is the result
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of the last @racket[defn-or-expr] if it is an expression,
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@|void-const| otherwise. If no @racket[defn-or-expr] is provided
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(after flattening @racket[begin] forms), the result is @|void-const|.
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The final @racket[defn-or-expr] is executed in tail position, if it is
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an expression.
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@examples[#:eval ev
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(define (f x)
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(block
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(define y (add1 x))
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(displayln y)
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(define z (* 2 y))
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(+ 3 z)))
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(f 12)
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]}
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@close-eval[ev]
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