Applications of Functional Programming

Many of these are anecdotal and lacking in references, but I think the breadth of the applications and the general success of the projects are compelling reasons for people to more actively consider these languages for projects, both for raw computation and especially for providing extension and glue languages over lower level computational engines that may be written in some other language.

If you have any information on other commercial, industrial, or other application (except teaching or Programming Language research), please Dave Mason. If you have special libraries or foreign function interfaces, please do likewise (preferably including the information below). Or if any of the people mentioned here don't want to be attributed, or want a web page link added, or want to correct an email address, send me mail.

If, having looked at all this, you want to learn more, my Scheme page or one of the links above should help.

• Autocad is built around Lisp.
• The Emacs editor is entirely customized (and a majority of the functionality is written) in Lisp.
• Softquad is doing web development in Scheme.
• Ericsson has 300-400 programmers developing telecoms products in the functional language Erlang, with usage increasing.
• IS Robotics is using Lisp for real-time control of robots.

• The video game `Abuse' is written in Lisp.
• (Softquad's) Hot Metal is largely coded in Scheme.
• A signal-processing company considers Scheme their `silver-bullet' for their toolkit software.
• US miliary logistics software that was a major success of the Gulf War was written in Lisp (DOD estimates that savings from that program alone paid back every penny of AI research funding they had ever spent!).
• Super-Mario-64 is significantly Lisp.

Lucent Technologies, formerly AT&T Network Systems and Bell Labs Research, has licensed Allegro CL products for the past 10 years. Lucent's various projects involving Allegro CL development have included a distributed service workbench for video on demand applications over ATM, ATM switching, and interfaces to various database systems.

A switching application known as the Globeview-2000 Broadband System was developed to accommodate new or custom services such as routing by call origin, call forwarding, universal telephone numbers, voice mail and other services. These services could be updated on-the-fly to a running switch because of Allegro CL's Dynamic Objects technology.

They do 3-D animated graphics (systems and product -- ads). The company is descended from the Symbolics Graphics division.

There are two commercial VLSI CAD tools (that I know of) that are widely used in the semiconductor industry and that are implemented in Scheme. Both involve significant numerical computation. The first is VeriCheck by Integrated Silicon System and the second is ArcCell by Arcsys. Both companies have now been absorbed into a company called Avant! and the progam names have been changed to Hercules and Aquarius, resp. Hercules is a design rule checker and Aquarius is a place and route tool. Both provide APIs via Scheme. I have run Hercules on very large chip designs (millions of transistors) and speed is no problem. FWIW, in VLSI CAD correctness is probably more important. If Scheme provides that at a cost of 5-10% speed, then it's worth the price.

Alfred J. Reich, Austin, Texas, USA, <reich@io.com>

In article <01bc34da$c82c69c0$677f2dc7@stanton>, "Stephen Tanton" <stanton@isn.net> wrote:
>
> Please don't lynch me for asking this, but what is the use of scheme.
>
> The reason I ask this is after taking a comparative languages course and a
>course in OOP I'm not so sure that I like where some people say programming
>is going, ie towards OOP languages such as C++/Java or (ugh) visual
>languages.  Now after looking at the functional languages such as
>scheme/lisp it kind of makes me wonder if maybe we shouldn't be looking
>harder towards other programming paradigms such as the functional or
>logical models.
>
>Of course I'm not saying that we should be trying to fit every software
>solution into a particular paradigm, I just think that as a programmer I
>shouldn't put all my faith in one type of language, which is why I posed
>this question.  In the end I guess I'm just looking for some insight from
>some more experienced programmers out there as to when I should think about
>using some of these less publicized languages.

In article <01bc3800$ddc10060$0f02000a@gjchome.nis.newscorp.com>,
George J. Carrette <gjc@delphi.com> wrote:
>
>Also, some people have used scheme for spreadsheets, such as:
>Siag is a spreadsheet based on X and Scheme. It is copyrighted by its
>author, Ulric Eriksson, under the Gnu Public License. See Copying
>for details

I know of at least three other spreadsheet projects using Scheme. Also, the Gimp (GNU Image Processing Program) uses Scheme for a type of plug-in.

A good reason to use Scheme as an extension language, embedded interpreter or somesuch is that you get a real, flexible language as opposed to hacking your own or using something like Tcl. Also, at least with Siod, the size is small enough to justify its use in almost *any* program, however small. Most programs use configuration information in some form. Reading the configuration requires error checking. Why write it yourself, probably forcing your users to learn a new file format, when it can be done with existing stuff based on standards.

Craig Earls writes:
>Unless you need speed. Scheme seems pretty slow, of course that could
>be my naive programming style...

I found on the benchmarks I tried that Sun's f77 was the fastest, followed by Scheme.

In short, how fast or slow "Scheme" is depends on your computer, your problem, your program, and your compiler.

One of the reasons Scheme is a useful language is that it is simple enough that one man (Jeff Siskind) can write an extremely smart compiler for it. Of course, it _is_ a one-man compiler, and there are programs where other compilers do better.

Speeds vary widely amongst Lisp compilers as well. GCL is not one of the best. On the other hand, speeds also vary widely between C compilers, and I have actually measured a FIFTY TO ONE speed ratio for the same C source code compiled by different compilers on the same UltraSPARC.

Somebody wrote:
> Scheme is useful any time you need a small, clean, expressive,
> interactive programming language.  The Virtual Reality team at
> Walt Disney Imagineering uses a combination of Scheme and C++ in
> their VR implementation.  I've heard that people at Microsoft are
> using Scheme to analyze legacy C code. I've also heard that JPL
> is using Scheme to program robots.  Scheme would have made a much
> better Java than Java, but it didn't look enough like C++.

<mwette@mr-ed.jpl.nasa.gov> (Matthew R Wette) writes:
> I know of a LISP effort (not
> Scheme).  There is currently a project under development (to launch
> next year some time) which may use LISP for the Remote Agent, which
> will make the spacecraft autonomous.  It includes a planner, a smart
> executive and a model identification and reconfiguration system.

Great idea:
It is also possible to use foreign function interfaces to couple Scheme with a library of C functions for simulations -- control systems, networks, communication links. The functions themselves are dynamically linked to a scheme MOP such as stklos, and communicate between each other using the Unix socket interface. Multithreading or forking would allow the ability to spread load over multiple machines or processers, while the Scheme script has the ability to inspect, alter and display data, as well as to facilitate quick prototyping.

The only product in the market that comes close to achieving this functionality is a package marketed by Mathworks known as Matlab. [...]

I always use "slower" high-level languages, because the programs I use are usually executed once, or a dozen times at most. I try to minimize my programming time. The program may take 15 minutes to write and 15 minutes to run, but that's still less time it would take me to just write it in C++.

1. We made a generic multi-player game system. The clients are generic Scheme interpretors, the server sends over Scheme code for them to execute. If the server sends the chess code, the client becomes a chess player. If the server sends the checker code, it becomes the checker player. This allows one code on the client side to morph and adapt to the human player.

2. We made a generic, multi-language (C, C++, Fortran, Pascal) debugger front-end. The user options and configuration is stored in Scheme format. The debugger, when started, loads the configuration file, feed it to the embedded interpretor, and initialize the debugger internal state. The debugger backend (the one that controls the debugged process and plays with the symbol table) sends over the data structure and prin format in Scheme as well. The front-end simply interpretes the Scheme code from the backend to do the printing.

>>>>> "Johann" == Johann Hibschman <johann@physics20.berkeley.edu> writes:

    Johann> Hi, I've just recently dropped into this newsgroup, so I
    Johann> don't know if this has been discussed at all.  Is scheme
    Johann> ever used for large scale numerical work, like numeric
    Johann> integration of functions, hydrodynamic codes, matrix
    Johann> manipulation, etc.?  Are the compilers capable of the

    Johann> required optimizations to get acceptable performance?  C++

    Johann> is slower than C which is slower than Fortran; if Scheme
    Johann> is much slower than C++, then it is nigh-useless.
                                          ^^^^^^^^^^^^^^^^^^

stalin

Usually produces code about the same speed as the C code - sometimes faster and sometimes slower.

bigloo

Produces smaller binaries than scheme->C. Can produce very fast code (close to C speed) if you explicitly tell it to use all floating point numbers or all integers (if that's applicable).

gambit-C

Usually much faster than generic bigloo (no math switches), sometimes a little slower.

hobbit

Can produce fast code, but might require tweaking of the C code produced, and might require switches similar to those required by bigloo & gambit-C.

scheme->C

produces slow code & big binaries.

Several successful products and internal projects at Sun were written in esh.

• If you look at the project files generated by the old DevGuide user interface builder, for example, you should not be surprised to see parentheses scattered about in abundance.
• The TNF tools, a set of trace generation and analysis tools for Solaris, were written in esh.
• My own project uses esh, too. I am responsible for a large distributed resource sharing system that runs about 3000 SPARC-10 equivalent hours of jobs every hour in one building alone, and the central scheduler is written almost entirely in Scheme.

Well, AT&T was doing a switching system in Lisp and another one in C++. The C++ system did take a lot more resources (it was done as a production system). The Lisp version was more like a research project (let's see what we can do). As it turned out the Lisp version did have more functionality at comparable speed and was *much* cheaper to built.

This was a large project (if I remember correct, up to 100 people were working on the switch based on Lisp). It did touch areas like real-time GC, OODBMs, fault tolerance, the system should be down in the range of a minute per year, etc.

The group has reported about that publicly and they seemed a bit frustrated that despite the clear superiority of their switch, the company still wanted to market the system based on C++.

Here is a list of some users of SIOD (a very small Scheme implementation).

SML-NJ development projects.

Some of these respondents are also found above.