[Chicken-janitors] #337: Support "fender" in syntax-rules

[Chicken Trac]

#337: Support "fender" in syntax-rules
-------------------------------+--------------------------------------------
 Reporter:  kon                |       Owner:       
     Type:  enhancement        |      Status:  new  
 Priority:  not urgent at all  |   Milestone:  4.7.0
Component:  expander           |     Version:  4.5.x
 Keywords:                     |  
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 * Allow optional "fender" in `syntax-rules'

   * <pattern> <fender> <template>

   * <fender> is an <s-expr> that must evaluate to "true"

   * <fender> is evaluated as (and <fender> #t)

 + Useful since an er-transformer would otherwise be necessary for very
 common tasks.

 - Muddies syntax-rules in that a procedural element is introduced

 ---

 - (identifier? obj)

 (define (identifier? obj)
   (let ((sans (strip-syntax obj)))
     (and (symbol? sans) (not (keyword? sans)) ) )

 -(bound-identifier=? id1 id2)

 -(free-identifier=? id1 id2)

-- 
Ticket URL: <http://bugs.call-cc.org/ticket/337>
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Chicken Scheme is a compiler for the Scheme programming language.