74 lines
2.6 KiB
Racket
74 lines
2.6 KiB
Racket
#lang scribble/manual
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@(require scribble/struct scribble/decode scribble/eval "utils.rkt"
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(for-label racket/base racket/contract unstable/wrapc racket/syntax syntax/parse))
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@(define the-eval (make-base-eval))
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@(the-eval '(require racket/contract (for-syntax racket/base unstable/wrapc)))
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@title[#:tag "wrapc"]{Contracts for Macro Subexpressions}
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@unstable[@author+email["Ryan Culpepper" "ryanc@racket-lang.org"]]
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@defmodule[unstable/wrapc]
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This library provides a procedure @racket[wrap-expr/c] for applying
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contracts to macro subexpressions.
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@defproc[(wrap-expr/c [contract-expr syntax?]
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[expr syntax?]
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[#:positive pos-blame
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(or/c syntax? string? module-path-index?
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'from-macro 'use-site 'unknown)
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'use-site]
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[#:negative neg-blame
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(or/c syntax? string? module-path-index?
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'from-macro 'use-site 'unknown)
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'from-macro]
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[#:name expr-name
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(or/c identifier? symbol? string? #f) #f]
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[#:macro macro-name
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(or/c identifier? symbol? string? #f) #f]
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[#:context context (or/c syntax? #f) (current-syntax-context)])
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syntax?]{
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Returns a syntax object representing an expression that applies the
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contract represented by @racket[contract-expr] to the value produced
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by @racket[expr].
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The other arguments have the same meaning as for @racket[expr/c].
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@examples[#:eval the-eval
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(define-syntax (myparameterize1 stx)
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(syntax-case stx ()
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[(_ ([p v]) body)
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(with-syntax ([cp (wrap-expr/c
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#'parameter? #'p
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#:name "the parameter argument"
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#:context stx)])
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#'(parameterize ([cp v]) body))]))
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(myparameterize1 ([current-input-port
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(open-input-string "(1 2 3)")])
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(read))
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(myparameterize1 (['whoops 'something])
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'whatever)
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(module mod racket
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(require (for-syntax unstable/wrapc))
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(define-syntax (app stx)
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(syntax-case stx ()
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[(app f arg)
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(with-syntax ([cf (wrap-expr/c
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#'(-> number? number?)
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#'f
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#:name "the function argument"
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#:context stx)])
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#'(cf arg))]))
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(provide app))
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(require 'mod)
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(app add1 5)
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(app add1 'apple)
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(app (lambda (x) 'pear) 5)
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]
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}
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@close-eval[the-eval]
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