56 lines
1.9 KiB
Racket
56 lines
1.9 KiB
Racket
#lang scribble/doc
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@(require "common.ss"
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(for-label syntax/stx))
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@title[#:tag "stx"]{Deconstructing Syntax Objects}
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@defmodule[syntax/stx]
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@defproc[(stx-null? [v any/c]) boolean?]{
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Returns @scheme[#t] if @scheme[v] is either the empty list or a
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@tech[#:doc refman]{syntax object} representing the empty list (i.e.,
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@scheme[syntax-e] on the @tech[#:doc refman]{syntax object} returns
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the empty list).}
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@defproc[(stx-pair? [v any/c]) boolean?]{
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Returns @scheme[#t] if @scheme[v] is either a pair or a syntax object
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representing a pair (see @techlink[#:doc refman]{syntax pair}).}
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@defproc[(stx-list? [v any/c]) boolean?]{
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Returns @scheme[#t] if @scheme[v] is a list, or if it is a sequence of
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pairs leading to a syntax object such that @scheme[syntax->list] would
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produce a list.}
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@defproc[(stx->list [stx-list stx-list?]) list?]{
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Produces a list by flatting out a trailing syntax object using
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@scheme[syntax->list].}
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@defproc[(stx-car [v stx-pair?]) any]{
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Takes the car of a @techlink[#:doc refman]{syntax pair}.}
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@defproc[(stx-cdr [v stx-pair?]) any]{
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Takes the cdr of a @techlink[#:doc refman]{syntax pair}.}
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@defproc[(module-or-top-identifier=? [a-id identifier?]
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[b-id identifier?])
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boolean?]{
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Returns @scheme[#t] if @scheme[a-id] and @scheme[b-id] are
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@scheme[free-identifier=?], or if @scheme[a-id] and @scheme[b-id] have
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the same name (as extracted by @scheme[syntax-e]) and @scheme[a-id]
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has no binding other than at the top level.
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This procedure is useful in conjunction with @scheme[syntax-case*] to
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match procedure names that are normally bound by MzScheme. For
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example, the @scheme[include] macro uses this procedure to recognize
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@scheme[build-path]; using @scheme[free-identifier=?] would not work
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well outside of @scheme[module], since the top-level
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@scheme[build-path] is a distinct variable from the MzScheme export
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(though it's bound to the same procedure, initially).}
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