Dave Herman (dherman who is at ccs dot neu dot edu) sent me a very insightful
email. With his permission, I'm reposting it to the list, as I received it.
It notes an error I made in discussing "and" and "or" in Scheme.
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I am a fan of your work on "sweet-expressions". I think it has a lot of
promise. (And the page is so well-written, too!)
One minor note on your recent blog entry about it. You claim that && and
|| can be aliased to AND and OR, respectively, by writing:
(define && and)
(define || or)
This isn't quite true, at least in Scheme. Since AND and OR are not
functions but rather special forms, you need macros for this.
(define-syntax &&
(syntax-rules ()
((&& exprs ...)
(and exprs ...))))
Or you could use a simple aliasing macro:
(define-syntax define-alias
(syntax-rules ()
((define-alias x y)
(define-syntax x
(syntax-rules ()
((x exprs (... ...))
(y exprs (... ...))))))))
(define-alias && and)
(define-alias || or)
(I'm not sure what the corresponding surface syntax for the above would
be in the context of sweet-expressions.)
Dave
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(My thanks to Dave Herman. My tests _had_ worked in Guile, which led me
astray. He correctly noted that some Schemes don't have a strict phase
separation between macros
and evaluation. Obviously, guile is one of them.)
