Re: [Chicken-hackers] Strange macro expansion

[Peter Bex]

On Tue, Jul 30, 2013 at 08:10:58PM +0200, Jörg F. Wittenberger wrote:
> ;; Hi All,

Hi, Joerg!

> ;; This looks wrong to me.  I'd expect both tests to the same thing.

I believe this is similar to the following classic example:

(let ((else #f))
  (cond (else 1))) ;; => void

Because else is lexically bound, it will not match the keyword literal.

>From R5RS (4.3.2):

``Identifiers that appear in <literals> are interpreted as literal
  identifiers to be matched against corresponding subforms of the
  input. A subform in the input matches a literal identifier if and
  only if it is an identifier and either both its occurrence in the
  macro expression and its occurrence in the macro definition have
  the same lexical binding, or the two identifiers are equal and both
  have no lexical binding.''

In this case, one has a lexical binding and the other has no lexical
binding (a free identifier).  Therefore, it shouldn't match.

Cheers,
Peter
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