CScheme question

[Evan Kirshenbaum]

I recently started using CScheme, and I have a question about the
efficiency of the compiler. When writing macros, a common idiom I use
is:
`(lambda ,args
(let (,@(and var1
`((,var1 ,(generate-uninterned-symbol))))
,@(and var2
`((,var2 ,(generate-uninterned-symbol))))
...)
...))
where temporary variables are gensymed only if they are needed. If no
variables are needed, what comes out is
(lambda (x y z)
(let ()
...))

Now in any other lisp/scheme the internal let binding would be
discarded. In CScheme, it would seem that the internal environment
would have to be created because of the way define works. I use this
idiom a lot, and wind up with functions that pp as (let () (let ()
...)). My question is: is the compiler smart enough to realize that
no defines occur in the body, and so no environment is needed, or do I
have to make macros condition on the presence/absence of temporary
variables?

---
Evan Kirshenbaum
Stanford University
ev...@CSLI.STANFORD.EDU
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