fc52248446
Support for break clauses complicates expansion to `for/fold/derived'; a new `syntax/for-body' library provides a helper for macros that need to split a `for'-style body into a prefix part and wrappable part.
22 lines
885 B
Racket
22 lines
885 B
Racket
#lang scribble/manual
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@(require (for-label racket/base
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syntax/quote))
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@title{Parsing @racket[for] Bodies}
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@defmodule[syntax/for-body]{The @racketmodname[syntax/for-body] module
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provides a helper function for @racket[for]-like syntactic forms that
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wrap the body of the form while expanding to another @racket[for]-like
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form, and the wrapper should apply only after the last
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@racket[#:break] or @racket[#:final] clause in the body.}
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@defproc[(split-for-body [stx syntax?] [body-stxes syntax?]) syntax?]{
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The @racket[body-stxes] argument must have the form
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@racket[(_pre-body ... _post-body ...)], and it is rewritten into
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@racket[((_pre-body ...) (_post-body ...))] such that
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@racket[(_post-body ...)] is as large as possible without containing a
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@racket[#:break] or @racket[#:final] clause.
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The @racket[stx] argument is used only for reporting syntax errors.}
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