A small survey (if you have couple of minutes) - comp.lang.lisp

Message from discussion A small survey (if you have couple of minutes)

Erann Gat

More options Aug 26 2001, 2:27 am

Newsgroups: comp.lang.lisp

From: g...@flownet.com (Erann Gat)

Date: 25 Aug 2001 23:27:00 -0700

Subject: Re: A small survey (if you have couple of minutes)

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richar...@gmx.net (Richard Krush) wrote in message <news:slrn9ogpo9.2ueb.richard_k@localhost.localnet>...
> Hello!

Hi Richard!

> Please excuse me if this type of articles are not welcome here, but I
> would like to ask you one question which gives me troubles in my
> "intrahead" debates about whether to invest more time in learning LISP
> or just continue with C or another popular language.

No apologies needed. This is a perfectly fine article.

> I know that LISP is very successfuly used in a few complex industrial
> programs (and if believe the list on www.lisp.org, many more I've never
> head of) as well as several userland applications such as EMACS. I also
> know LISP can be used as THE most powerful scripting language instead
> of shell scipting or even Perl/Python.

> What I would like to know is what uses do you (meaning people who post
> in this group or read it) use LISP for?

Lisp was the third programming language I learned, after Basic and
Pascal. I first used it in 1981 on an Apple II, and I've been
programming in it ever since. In college I used it for just about
everything, including my CS class assignments. My colleagues worked
in Pascal mostly (this was when C was just beginning to get popular,
and Bjarne Stroustrup had not yet invented C with objects, which would
later become C++). They would work on a typical assignment for days
and turn in code printouts that were many inches thick. I would work
for an hour or two and turn in code that only took up a few pages.
(And I got A's.)

From 1988 to about 1992 I used Lisp to program a series of research
robots that eventually led to the Sojourner Rover on the Mars
Pathfinder mission. (Sojourner itself was programmed in C.) The
robots themselves did not run Lisp, their processors were too small
(8-bit processors with only a few k of RAM). Instead I used Lisp to
write a compiler for a custom-designed robot programming language that
compiled to machine code for the robot's processors. Writing the
compiler took only a couple of weeks (and would have only taken a
couple of days if I'd actually known what I was doing).

In 1993 I used Lisp to program a robot for the AAAI mobile robot
contest. I started working on the code for the contest on the flight
to the conference. The total time I spent coding was three (very
intense) days. I took a first and a second place, competing against
teams of programmers working for weeks or months in C.

In 1994 I used Lisp to produce a code patch for an instrument on the
Galileo spacecraft in orbit around Jupiter. The instrument (a
magnetometer) was programmed in Forth, and had developed a bad memory
byte (out of a total 4k bytes of memory). It was estimated that to
patch the Forth code (which is notoriously difficult to maintain)
would take so long that it was not feasable. I wrote a customized
Forth development environment in Lisp that was used to produce a code
patch. The total time it took to produce the development environment
and the code patch was three months. (The resulting patch is flying
today. It's the only thing this development environment was ever used
for.)

From 1995 to about 1998 I was part of a team using Lisp to program an
autonomous spacecraft (a project called Remote Agent which flew on a
spacecraft called DS1). At one point part of the team tried to
re-implement their part of the software in C++. After a year the
effort was declared a failure and they went back to Lisp.

In 2000 as an excercise I wrote a fully functional Web server in Lisp.
It took me about a month. It includes GET and POST methods, file
upload capability, user authentication, in short, just about
everything (except documentation).

I've written cryptography code, and robot and spacecraft simulators in
Lisp.

In short, I've used Lisp to do just about everything.

Erann Gat
g...@flownet.com

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