Subject: Re: Macros in Common Lisp, Scheme, and other languages From: Erik Naggum <email@example.com> Date: 07 Sep 2002 18:57:11 +0000 Newsgroups: comp.lang.lisp,comp.lang.scheme,comp.lang.functional Message-ID: <firstname.lastname@example.org> * Paul F. Dietz | I understand this. Sorry, that not clear to me from what you wrote. | The current scheme makes it hard for the user to do some things that the | compiler can do. Precisely, but there are different ways to accomplish this. If the compiler knows the type, you can let the macro expand to a `type-case´ form that the compiler should optimize away. If the compiler cannot optimize it away, it will be a run-time decision, instead, which may bloat the code but should yield nearly the same performance benefits. | I realize that macros can expand to arbitrary code. My suggestion was to | allow some way for the user to provide a hint to the system so it can | propagate information through unexpanded macros. Perhaps this could be | limited to compiler macros, which should be written to reflect the semantics | of the equivalently named functions anyway. I think macros are used where compiler-macros should be used mainly because the programmer does not know about compiler-macros. For some reason, they are not covered in many Common Lisp texts. -- Erik Naggum, Oslo, Norway Act from reason, and failure makes you rethink and study harder. Act from faith, and failure makes you blame someone and push harder.