方案宏的优点是什么？

Question

Why would anyone prefer Scheme macros over Common Lisp macros (and I genuinely want to know too, I'm not trying to be a troll)?

My experience as a Lisp newb is that Common Lisp style macros are much easier to learn than Scheme's macros. I have yet to see any advantages to Scheme's macros, but of course that doesn't mean they don't exist.

I do know that Scheme macros are "hygenic", but I'm still not convinced this is worth the additional complexity. On the other hand though, there obviously are people that are convinced that this is necessary, otherwise there wouldn't be implementations of Scheme macros in Common Lisp.

To make a long story short, can someone defend Scheme's macros to me?

转载于:https://stackoverflow.com/questions/3484094/what-are-the-advantages-of-scheme-macros

Answer 1

Scheme macros introduce two, essentially orthogonal, concepts: hygiene and pattern matching. Hygiene is less important in a lisp2 like Common Lisp. The pattern matching language captures many of the common macro idioms, but has the problem that it is essentially a different language from scheme. Probably the best introduction to scheme's macros, along with some of the rationale behind them is Shriram Krishnamurthi's PLAI chapters 36 and 37.

I suspect that the reason people write scheme style macro systems in common lisp is more for the pattern matching than for the hygiene.