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Re: lisp performance was Re: problems with lisp
There are pattern matchers for scheme, at least. IIRC there is code for
one in Essentials of Programming Languages; check out Dan Friedman's web
site. I'm sure there are similar facilities for lisp somewhere.
I don't see any reason why pattern matching shouldn't be just as popular in
lisp/scheme as it is in ML or Haskell. Erlang is dynamically typed and
Erlang programs use pattern matching all the time.
> Date: Mon, 25 Aug 2003 13:06:43 -0400
> From: Ken Anderson <firstname.lastname@example.org>
> You can find several papers on Lisp performance her:
> I'd be intersted in looking at your programs if you'd like.
> Unfortunately, Common Lisp does not require tail call optimization, though things like tail calls are usually optimized. You'd see stack overflows if this was an issue.
> First, I write Lisp straightforwardly. This version is often plenty fast enough. When its not, i profile (see for example, http://openmap.bbn.com/~kanderso/performance/postscript/courage-in-profiles.ps). I don't know if clisp or gcl have profilers however. Often a few relatively small changes can make a big difference. These may or may not require type declarations.
> Going from OCaml to Lisp you may lose information that OCaml takes advantage of.
> I agree that pattern maching makes the code cleaner.
> At 04:40 PM 8/22/2003 +0100, Russ Ross wrote:
> >Performance is still a bit of a sore spot, too. I hear that tuned
> >lisp code runs as fast as C code, but I'm still sceptical. I
> >recently implemented a fairly simple solution to the ILC programming
> >contest in both CL and OCaml. I wrote it first in OCaml as an
> >exercise to learn the language and then ported it to Lisp. It was
> >a purely functional solution and I was careful to use tail calls
> >when possible. The two solutions are almost identical in structure,
> >but the lisp version is about 10x slower. I tried it with two lisp
> >compilers (clisp and gcl) and they were about the same. I'm sure a
> >more experienced lisp programmer could tune it up nicely, but I have
> >much more lisp experience than OCaml experience and I was shocked
> >by the result. I don't trust a language where the clean, simple
> >approach is the slow one and requires careful annotations and
> >program restructuring to work around the idiosyncrasies of the
> >language. With Lisp it seems like there are two languages: the
> >simple one you teach people and use to demonstrate its virtues, and
> >the real one you use for high performance implementations. Can't
> >Simple Lisp be the same as High Performance Lisp? So far it sure
> >seems to work for OCaml. Pattern matching meant the OCaml code was
> >much more transparent as well (and I'm saying this as a complete
> >beginner with OCaml and ML in general).