ac26fe7554
Also, updates some of the mzlib files to point at `racket/*' libraries rather than to `scheme/*' ones.
83 lines
2.8 KiB
Racket
83 lines
2.8 KiB
Racket
#lang scribble/doc
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@(require "mz.rkt" (for-label racket/splicing racket/stxparam racket/local))
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@(define splice-eval (make-base-eval))
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@interaction-eval[#:eval splice-eval (require racket/splicing
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racket/stxparam
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(for-syntax racket/base))]
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@title[#:tag "splicing"]{Local Binding with Splicing Body}
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@note-lib-only[racket/splicing]
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@deftogether[(
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@defidform[splicing-let]
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@defidform[splicing-letrec]
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@defidform[splicing-let-values]
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@defidform[splicing-letrec-values]
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@defidform[splicing-let-syntax]
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@defidform[splicing-letrec-syntax]
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@defidform[splicing-let-syntaxes]
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@defidform[splicing-letrec-syntaxes]
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@defidform[splicing-letrec-syntaxes+values]
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@defidform[splicing-local]
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)]{
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Like @racket[let], @racket[letrec], @racket[let-values],
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@racket[letrec-values], @racket[let-syntax], @racket[letrec-syntax],
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@racket[let-syntaxes], @racket[letrec-syntaxes],
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@racket[letrec-syntaxes+values], and @racket[local], except that in a
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definition context, the body forms are spliced into the enclosing
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definition context (in the same way as for @racket[begin]).
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@examples[
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#:eval splice-eval
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(splicing-let-syntax ([one (lambda (stx) #'1)])
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(define o one))
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o
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one
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]
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When a splicing binding form occurs in a @tech{top-level context} or
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@tech{module context}, its local bindings are treated similarly to
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definitions. In particular, if a reference to one of the splicing
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form's bound variables is evaluated before the variable is
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initialized, an unbound variable error is raised, instead of the
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variable evaluating to the undefined value. Also, syntax bindings are
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evaluated every time the module is @tech{visit}ed, instead of only
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once during compilation as in @racket[let-syntax], etc.
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@examples[
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#:eval splice-eval
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(splicing-letrec ([x bad]
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[bad 1])
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x)]
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}
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@defidform[splicing-syntax-parameterize]{
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Like @racket[syntax-parameterize], except that in a definition context, the body
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forms are spliced into the enclosing definition context (in the same way as for
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@racket[begin]). In a definition context, the body of
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@racket[splicing-syntax-parameterize] can be empty.
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Note that @tech{require transformers} and @tech{provide transformers} are not
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affected by syntax parameterization. While all uses of @racket[require] and
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@racket[provide] will be spliced into the enclosing context, derived import or
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export specifications will expand as if they had not been inside of the
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@racket[splicing-syntax-parameterize].
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@examples[
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#:eval splice-eval
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(define-syntax-parameter place (lambda (stx) #'"Kansas"))
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(define-syntax-rule (where) `(at ,(place)))
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(where)
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(splicing-syntax-parameterize ([place (lambda (stx) #'"Oz")])
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(define here (where)))
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here
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]}
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@; ----------------------------------------------------------------------
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@close-eval[splice-eval]
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