From ...
From: Erik Naggum <erik@naggum.no>
Subject: Re: Waving the lambda flag again (was: Constants and DEFCONSTANT)
Date: 1999/04/01
Message-ID: <3131961221139730@naggum.no>#1/1
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References: <nkjpv5y244f.fsf@tfeb.org> <sfwk8w5eu91.fsf@world.std.com> <ixhfr4njna.fsf@gaspode.cam.harlequin.co.uk> <sfw3e2nbwmu.fsf@world.std.com> <7dr23c$2re$1@shell5.ba.best.com>
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Organization: Naggum Software; +47 8800 8879; http://www.naggum.no
Newsgroups: comp.lang.lisp

* chucko@best.com (Chuck Fry)
| Modern Common Lisp compilers allow me to tune the critical parts of my
| code to within a few percent of C code, but without the pain of using a
| fragile, brittle quasi-portable assembly language.

  just for the heck of it: I have tuned a _very_ CPU-heavy function I wrote
  in Common Lisp over a year ago so it went from the unsatisfactory 623 µs
  per call to the very pleasant 4.7 µs per call.

  the strictly equivalent C function that people are entirely _satisfied_
  with, performance-wise, takes 92 µs per call.  very frequently, I find
  that Common Lisp allows me to experiment with algorithms so much faster
  than I can in C and the like, so I can change methodology and approach as
  fast as they can do another optimization attempt.  this means that a good
  Common Lisp programmer can find the optimal algorithm _and_ the optimal
  implementation in less time than the C programmer can find the optimal
  implementation.

  the C mind-set is that C is fast.  this is even less true than their idea
  that CL is slow.  writing really fast C code is _incredibly_ hard, and
  you might as well write it in assembly after you have seen what the
  compiler is doing to the overall code.  I have squeezed the last drop of
  blood out of many a CPU in my time, but never has it been easier to do it
  than with Allegro CL with its instruction-level profiler, hackable LAP
  code (thanks, Duane!), and code transformation with compiler macros (a
  standard CL facility).  this stuff just isn't available to C programmers.

  if you can't outperform C in CL, you're too good at C.

#:Erik