Lisp in the real world

Question

I have experimented with Lisp (actually Scheme) and found it to be a very beautiful language that I am interested in learning more about. However, it appears that Lisp is n

Answer 1

ITA Software uses Common Lisp for its QPX low-fare search engine which powers sites like Orbitz, Kayak, and American and United Airlines among many others. It's also used in part for its upcoming passenger reservation system for Air Canada. Paul Graham has written a little bit about Lisp at ITA in the past.

(Disclaimer: I work there.)

Answer 2

Reddit was originally written in Lisp and then later rewritten in Python. There's a good analysis of the switch and what it means for Lisp over at Finding Lisp.

Answer 3

A fairly recent open-source project that is still enjoying consistent and considerable development activity is LilyPond.

It's a music notation program that takes a easy-to-write text file as input and converts it into beautiful sheet music (pdf files). Offers all kinds of ways to fiddle with the output if you want to. It can even produce decent sounding midi files. I use it whenever I need to produce nice sheet music that other musicians will read from. I think it's better than Finale and it's free!

In the commercial category, there is also Notehead's Igor Engraver. Unfortunately, the site doesn't allow me to post a direct link to the page that talks about Lisp, so go to downloads and look at the bottom for a "Lisp" link.

There's also Naughty Dog (a computer game company) who use Lisp in their games. This article talks about that and even shows some code.

And there are many others that have been mentioned and linked to, but these are the main ones that resonate with me (being a composer/programmer/gamer/... type).

Answer 4

The Hubble Space Telescope is scheduled using Lisp planning tools. The Space Shuttle was. The Webb telescope will be. The company I write Lisp for analyzes billions of dollars of health insurance claims and has been growing at ~30% per year even through the recession. We've been bought by a huge company, and one of our programmers matched (actually improved upon) the output of (huge company)'s software for analyzing Medicare claims, starting from scratch, by himself, in a year. (huge company)'s code, not in Lisp, took 6 years and several programmers. The trouble, career-wise, is that too many listen to the twaddle about "lots of irritating silly parentheses" and so on. Most managers don't "get it" and would rather have a project in a language familiar enough that they can micro-manage. They think "Lisp=AI" and don't even want to entertain the possibility that it's a good general purpose language. They just plug their ears. There aren't polished tools for doing M$-friendly websites or clustering or pipelining existing Java apps, and that's 90% of what IT cares about in these days of growth by acquisition. I could go on, but it would just get me bitter. :)

Answer 5

Peter Christensen has compiled a great list of (financially) successful lisp companies.

http://www.pchristensen.com/blog/lisp-companies/

Answer 6

Lisp is used in real-world algorithmic music composition with the Common Music library. Rick Taube's Notes from the Metalevel is a great introductory text to the subject which has a bunch of examples in Lisp for composing. See the examples directory here and a copy of the text here.