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Add example to the free-vars docs.

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Thanks to Christophe Scholliers.
This commit is contained in:
Vincent St-Amour 2016-04-27 11:02:22 -05:00
parent 45acc19f44
commit caebbc65b6
1 changed files with 17 additions and 1 deletions
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18
pkgs/racket-doc/syntax/scribblings/free-vars.scrbl
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@ -1,5 +1,5 @@
#lang scribble/doc #lang scribble/doc
@(require "common.rkt" (for-label syntax/free-vars)) @(require "common.rkt" (for-label syntax/free-vars) scribble/example)
@title[#:tag "free-vars"]{Computing the Free Variables of an Expression} @title[#:tag "free-vars"]{Computing the Free Variables of an Expression}
@ -23,3 +23,19 @@ sub-expressions before extracting identifiers. The default
If @racket[module-bound?] is non-false, the list of free variables also If @racket[module-bound?] is non-false, the list of free variables also
includes free module-bound identifiers. includes free module-bound identifiers.
@examples[
(require (for-syntax racket/base syntax/parse syntax/free-vars))
(define-syntax (print-body-free-vars stx)
(syntax-parse stx
#:literals (lambda)
[(_ (~and lam (lambda (a ...) b ...)))
(define expanded-body (local-expand #'lam 'expression '()))
(syntax-parse expanded-body
#:literals (#%plain-lambda)
[(#%plain-lambda (arg ...) body)
(displayln (free-vars #'body))
expanded-body])]))
(lambda (x) (print-body-free-vars (lambda (y) x)))
]