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 never used serious projects, and I haven't seen it listed as a desired skill on any job posting. I am interested in hearing from anyone who has used Lisp or seen it used in the "real world", or who knows whether it is considered a purely academic language.

+6  A: 

If I started up my very own major software project now, I would make my language decision based on the criteria above. Sure, I love Lisp, CLOS is awesome, real lexical scoping rocks, Lisp macros are way cool (when used as directed), and personally I really like Lisp syntax. […] But it would take a lot, or require special circumstances, to persuade me to choose Lisp for a major software project, if I were in charge of making the choice. - Dan Weinreb

Ólafur Waage
Right - then enjoy not being able to hire anyone :)
@Jeff: "But it would *take a lot*, or *require special circumstances*, to persuade me to choose Lisp for a major software project". It is a point against Lisp.
J.F. Sebastian
where's this quote from? googling by text chunks only yields this very post
Chris Jester-Young
Thanks Chris. The comment of Dan Weinreb is worth reading.
J.F. Sebastian
cheers. i have to say, this quote reads stronger then it really is, outside of context. weinreb is now working at ITA, and blogging about lisp among other things; i wonder how and if that might've influenced his opinion.
+12  A: 

Paul Graham has used and written about ViaWeb that was written in LISP

Read about it here - Beating the Average

Thats not really a good example, they went out of business years ago
BTW, can I just add that I think Paul is delusional on this one: it was not LISP that gave them the edge, it was just being smart and paying attention. They could have succeeded with VB if that was the only tool at hand.
They didn't go out of business, they were bought up by Yahoo. Big difference, at least to the developers. :-)
Head Geek
If the best example that can be come up with got bought out years ago and was subsequently run into the ground, then LISP it shows that LISP isn't that great in the real world?
@1800: It only "got run into the ground" after Yahoo owned it and had it rewritten in another language, so stop strawmanning.
And since then there have been no other significant examples of LISP being used in the real world, and if it was any good they would have kept using it written as LISP?
@1800: You seem to deliberately misunderstand the responses to your flamebait. Why don't you simply broaden your horizon by trying Lisp out for yourself instead of concluding it isn't “any good” from what other people have decided to do based on some circumstances that you don't know anything about?
Matthias Benkard
@1800: Forget what Matthias said, I actually think its quite funny. Your assertion that "there have been no other significant examples of LISP being used in the real world" directly implies that you are omniscient. Bravo!
@Ali: You win. :)
Matthias Benkard
+2  A: 

Look up ACL2. It's a lisp based formal logic engine that has been used for a number of "real world" project like formal methods in software security and proofs of correctness for Floating point hardware.

This is an amazing piece of software.
+2  A: 

It's a wonderful language, but it's crippled because (in my opinion as a software business owner and programmer) there are very few commercial Lisp packages, and the few that are out there demand a run-time fee (because a proper Lisp package can be used by end-users to write Lisp programs too).

I use Steel Bank Common Lisp to prototype code under Windows and Linux, and I love it -- but I would never consider shipping a product written with it. There's no easy way to set up single-click access to the programs, so that the end user will never be confronted with a Lisp prompt. There's no way to ship a compiled product so that the user can't disassemble it, make some changes to remove your name, and sell it as his own. I've seen mention of Lisp systems that both of these can be done in, but they're commercial ones where you have to pay run-time fees for each end-user of your program, which is ridiculous.

Lisp may come into its own some day (and I fervently hope that it does), but it isn't viable for most commercial software yet. The only exception is something where it's always going to be running on systems that you have complete control over, like a web server (and I've only heard of a couple companies using it even for that).

Head Geek
you can make executables with sbcl (they will be huge, though).i like the way everything is opensource around lisp. i'm very reluctant to depend on non-OSS components and all our stuff is OSS. anything can be disassembled, hacked and re-sold. the fix should happen at the marketing department...
Attila Lendvai
"It's a wonderful language, but it's crippled because (in my opinion as a software business owner and programmer) there are very few commercial Lisp packages, and the few that are out there demand a run-time fee (because a proper Lisp package can be used by end-users to write Lisp programs too)."Not true e.g for LispWorks on Windows, Mac, and Linux
Interesting... that's the only one I've seen that doesn't demand a run-time fee. They may be the salvation of Lisp for commercial software.
Head Geek
+14  A: 

Does Emacs' elisp count? That's the most "real world" use that I am familiar with (although I'm not sure that Emacs counts as "real world" either).

+6  A: 

Far from exhausted list in

+5  A: 

I believe Autocad has extensions that use Lisp to extend the product. See AutoLISP.

Alex Miller
Correct. It also implements ActiveX - it is quite powerful and AtoDesk themselves use it to write 'internal' commands. It is interpreted into ObjectARX - C++, basically.
CAD bloke
+13  A: 

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.

Mark Reid
+10  A: 

ITA software uses a fair amount of CL.

+20  A: 

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.)

Joe Shaw
+4  A: 

There are plenty of companies, projects, and products that use Lisp in a variety of roles — I've done work for several of them.

There are two relevant points:

  1. you may never know that your latest piece of consumer electronics was built with, or even programmed in, Common Lisp, or that some service you use is powered by a Lisp server. It would be incorrect to conclude that Lisp is "never used".

  2. … and, like so many domains, those jobs never appeared on Just because you've never seen a job posting for it doesn't mean that there are no Lisp-required or right-tool-for-the-job opportunities out there.

+19  A: 

Franz, Inc. provides an inexhaustive list of success stories on their website. However:

Please don't assume Lisp is only useful for Animation and Graphics, AI, Bioinformatics, B2B and E-Commerce, Data Mining, EDA/Semiconductor applications, Expert Systems, Finance, Intelligent Agents, Knowledge Management, Mechanical CAD, Modeling and Simulation, Natural Language, Optimization, Research, Risk Analysis, Scheduling, Telecom, and Web Authoring just because these are the only things they happened to list. — Kent Pitman

Matthias Benkard
That blurb seems like a very hollow mantra to me. Sure, it may be around in those areas, but then mostly as legacy code. In my experience from real life, Python combined with swigged C/C++ has much replaced Lisp as the rapid prototyping language(s) of choice for pragmatic hackers.
+1  A: 

If my plans work out, we will all be using Scheme in 5 years from now! ;p

My plans are probably quite similar:1) Make a kickass library on top of scheme (halfway there now).2) Test the library by writing cool programs in it (1 down, few more to go).3) Open source the library (already done but very casually).4) ...5) Lisp becomes the natural tool for a job at work.
+5  A: 

as a small startup we've built up something some people call an "application server". but in fact it's just a bunch of integrated common lisp libraries for sql connectivity and web applications. some details are available at cl-dwim project page

using that we have developed and operate a web application for the hungarian government that collect data from the local governments and calculates the relevant part of the budget of the country. this is the second budget we are planning now.

it has about 4000 users, and it runs on a cluster of computers.

as of "academic language": we are playing with things like persistent continuations for business process modelling. it's some random lisp code with a few extra process-related primitives and a few constraints. it can stop at random points in the code and fall asleep (get comitted into the database) while it waits for some external event.

is it practical or academic? you decide... :)

Attila Lendvai
+2  A: 

Well, it's hardly mainstream, but I use lisp for as much of my research code as is manageable. It's by far the best language I've found for the balance of dynamism & expressiveness while still generating decent performance for numerics, etc..

+7  A: 

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

Eric Normand
+7  A: 

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).


Scheme programming language is used as a scripting language by FLUENT Flow Modelling Software (computational fluid dynamics, CFD).

J.F. Sebastian

Just adding to all the very wise comments above: look at the Corman Lisp tool and discover how to embed VERY INTELLIGENT FUNCTIONS into an embedded system!

+1  A: 

For the AutoCAD application AutoLISP/Visual LISP are used a lot for real projects and there is a large community of users.

Jimmy Bergmark - JTB World

I was quite impressed when I found out that the PRISM («The Prism project is a long term project to build software tools for radiation therapy planning, including artificial intelligence tools as well as manual simulation systems.») is written in Common Lisp.

At my job I am writing software that uses DICOM and I must say that writing good DICOM implementation is a hard task. In their report they describe how Common Lisp let them build a good DICOM implementation that is better (at least in some ways) than other implementation with lesser effort.

+2  A: 

Some more recent ones:

The first three of those were written using Weblocks, a CL web framework. Wigflip and Clutu use pure Hunchentoot.

Now get coding! :)


Lisp attempted the jump to lightspeed in the early 80's. Before there were PCs, there were commercially produced "Lisp Machines" which superficailly look a lot like modern workstations, but which were lisp "all the way down". Lisp hardware eventually lost out to Intel (as did everything else). Lisp software eventually lost out to C/C++. There are a variety of theories why this is all this is so.


I see a few people have already mentioned it but lisp is widely used in custom Autocad development. Autocad includes a built-in lisp interpreter. It is one of the simplest ways to extend the product and provides the ability to quickly enhance your productivity.

No compiling is required, on the user side, and 1, or more, line lisp expressions can be entered on the command line and executed immediately on the drawing. For designers and draftsman willing to take even a small step to learning the basics of lisp it can provide a huge productivity boon.

Autocad does provide a number of other ways to customize their products; ObjectARX (C++), VB, C#, etc.. The lisp interface is by far the easiest to learn and implement. And the majority of other dev environments use lisp in some fashion.

The lisp interpreter was made available in a very early version of Autocad and was called Variables and expressions. It was fairly limited but was such a success with the users that additional functionality was quickly added. A full blown visual IDE was later on (in version 2000 I think).

I would hate to guess how many millions (billions?) of lines of lisp code are available for Autocad. A google search on "autocad .lsp" returns 2.3 million hits.

Ok, enough typing, it's back to work for me, writing more lisp for my current project :)

+2  A: 

Google App Inventor is written in Scheme

+2  A: 

The GIMP's plug-in system is based on Scheme, I believe. I don't know if this is completely "real world", but it seems to be a practical application of Lisp, at the very least.

Tikhon Jelvis