Opened 14 years ago

Closed 11 years ago

#337 closed enhancement (wontfix)

Support "fender" in syntax-rules

Reported by: Kon Lovett Owned by:
Priority: not urgent at all Milestone:
Component: expander Version: 4.5.x
Keywords: Cc: Kon Lovett
Estimated difficulty:


  • 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)

Change History (2)

comment:1 Changed 13 years ago by sjamaan

Milestone: 4.7.0

comment:2 Changed 11 years ago by sjamaan

Resolution: wontfix
Status: newclosed

Personally, I think this doesn't belong in syntax-rules. It's complex enough as it is, and we'll add more features piled on by R7RS soon, too.

This could be an egg.

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