2d4f3e2ac9
The layer is now redundant, since everything left in "pkgs" is in the "racket-pkgs" category.
40 lines
1.2 KiB
Racket
40 lines
1.2 KiB
Racket
#lang scribble/manual
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@(require (for-label racket/base
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racket/sequence
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syntax/unsafe/for-transform))
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@title{Unsafe @racket[for] Clause Transforms}
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@defmodule[syntax/unsafe/for-transform]{
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The @racketmodname[syntax/unsafe/for-transform] module provides a helper
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function that gives access to the sequence transformers defined by
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@racket[define-sequence-syntax]. This is what the @racket[for] forms use and
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enables faster
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@tech[#:doc '(lib "scribblings/reference/reference.scrbl")]{sequence} traversal
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than what the sequence interface provides.
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The output may use unsafe operations.}
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@defproc[(expand-for-clause [orig-stx syntax?] [clause syntax?]) syntax?]{
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Expands a @racket[for] clause of the form @racket[[(x ...) seq-expr]], where
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@racket[x] are identifiers, to:
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@racketblock[
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(([(outer-id ...) outer-expr] ...)
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outer-check
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([loop-id loop-expr] ...)
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pos-guard
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([(inner-id ...) inner-expr] ...)
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pre-guard
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post-guard
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(loop-arg ...))]
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which can then be spliced into the appropriate iterations. See @racket[:do-in]
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for more information.
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The result may use unsafe operations.
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The first argument @racket[orig-stx] is used only for reporting syntax errors.
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}
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