Add ellipsis quote and check behavior of _ in macros

[GoogleCodeExporter]

$ ol
You see a prompt
> (define-syntax foo 
      (syntax-rules () 
        ((_ 1 2) (_ 2 1)) 
        ((_ 2 1) 32)))
foo
> (foo 1 2)
What is '_'? 

Will have to check what the specs have to say about this. Will add if required 
or unspecified.

Original issue reported on code.google.com by aohelin on 24 Jan 2012 at 9:57

[GoogleCodeExporter]

Didn't spot anything about this in R7RS, but did spot some new and missing 
things
 - list beginning with ellipsis turns all ellipsis within a term into regular identifiers
 - underscore appearing in literals should take precedence over the wildcard behavior (possibly already does, just need to change the lines)
 - multiple pattern variable occurrences are disallowed (why? at least in non-ellipsis use they are simple and also useful)

Original comment by aohelin on 24 Jan 2012 at 10:13

[GoogleCodeExporter]

Original comment by aohelin on 9 May 2012 at 12:28

• Changed title: Add ellipsis quote and check behavior of _ in macros
• Added labels: Type-R7RS
• Removed labels: Type-Defect