Free "Lisp Hackers" Ebook

More than a year passed since I had started to publish a series of interviews with Lisp hackers. It was a great project, but I'm going to finalize it for now. All of the interviews are collected in a free ebook that is available through leanpub. You should share it with your friends and on the interwebs! ;)

Below is a few observations on the whole series that I think are interesting.

The Road to Lisp

There was a famous survey on the Association of Lisp Users site called "The Road to Lisp". I have somewhat replicated it in the interview and some of the answers where quite surprising, as far as I'm concerned.

First of all, people came to Lisp through friends, who gave them a copy of SICP or showed some fascinating Lisp programs. There's also a mention of online forums (usenet, irc, etc.)

So SICP is the most influential book, followed by Peter Norvig's PAIP. The other mentioned sources are "Writing GNU Emacs Extensions" by Bob Glickstein, "The UNIX-Haters Handbook", and Paul Graham's "Beating the Averages".

Two interesting things get notable mentions as leading to Lisp: computer graphics and Caml-light (for the French guys).

And receiving it as legacy from the dad is somewhat priceless!

I'd also like to add my experience here: the 2 things which brought me to Lisp were Eric S. Raymond's "How to Become a Hacker" which mentioned that you need to learn Lisp to become a better programmer, and Peter Seibel's great "Practical Common Lisp", which came out after all the interviewed hackers were already into Lisp, so they couldn't have been influenced by it.

Dislikes

This was an interesting question, because it made most of the persons go out of their comfort zone a little: after all, most of them are fond of Common Lisp. And the answers are interesting, although expected.

Basically, it boils down to 3 things:

• the arrogance of the community and/or outsiders prejudice against it
• lack of static typing and other ways to express constraints on the program
• disdain for the platform it lives on, which includes problems with embedding into other systems, no good way to write one-liners, etc.

Also noted were:

• necessity to struggle to achieve high performance
• the unspecified corners, but this problem is becoming less and less acute

A Lisp project

This was a question, proposed by Zach Beane: what Lisp project would you do if you weren't constrained in resources and other stuff. For the sake of completeness, I've also followed up with him, and here's his answer:

Right now I'd love to spend more time polishing Quicklisp. I'd love to make a good system for discovering the functionality you need (it's not easy to make the connection from "I need to fetch web pages" to "drakma"). I'd like to make interfaces for accepting user feedback and reviews. I'd like to make it easy to make connections from a project to its website, bug tracker, mailing list, documentation, etc. I'd like to publish my build tools and build logs. I'd like to make EVERYTHING a lot better, to make the system not just better than what CL had before but better than what other language ecosystems offer, too. It's all a lot of work.

As a fantasy project, I'd love to make a system for interesting visualization of complex data, something where it's easy to splat something quick and dirty on the screen/page, but which can grow in capability as the need arises. Or maybe just some tool for making audiovisual toys, with cool pictures and noises coming out.

The other interesting answers were:

• another take on reflection
• an OS, based on Linear Lisp, bootstrapped from Racket or Maru
• Lisp bridges to other runtime systems
• a Common Lisp object database
• a Go-playing program
• and, surely, an own Lisp dialect or even a separate programming language :)

Lisp companies

It's one of the popular myths that it's impossible to find a Lisp job. Well, it's definitely harder than to find a Java one, but speaking about the job's quality YMMV. Some of the Lisp companies were mentioned in the interviews:

• ITA Software that employed up to 50 Lisp developers in its Boston office and was bought by Google for almost $1B
• Franz in the Silicon Valley
• Teclo Networks in Switzerland
• MSI in Japan
• Novasparks which operates from Boston and Paris

But a lot more weren't mentioned. To name a few:

• probably, the biggest Lisp company in the world — the Portuguese SISCOG with 70+ Lisp developers
• Clozure Associates band of Lisp gurus from the US East Coast
• Copyleft from Norway
• RavenPack from Spain
• Australia's division of Accenture
• Agri-Esprit from France

I would say, that most of them work in pretty interesting domains and with challenging problems. There are also many more one- or two-man Lisp shops scattered around the world. So, yes, Lisp companies are rare, but there's nothing wrong with relying on Lisp in a company: it doesn't fail you and may even bring some outstanding results. Not to mention the fun of the process itself...

submit

Lisp Hackers: Marc Battyani

Marc Battyani is one of the people who put Lisp at the foundation of their business, and he doesn't seem to regret that decision. And the business itself is exploring very interesting aspects of high-performance and reconfigurable computing. Besides, he has a notable open-source contribution with cl-pdf/cl-typesetting libraries (which even I use, so thanks Marc!). He elaborates on all these and more in much detail in the interview.

Tell us something interesting about yourself.

I think maybe the most unusual things I do is that I work on very different application domains which are even sometimes completely at opposite extremes both in electronics and software. For instance form ultra low power smart sensors based on $1 microprocessors which will run continuously for 5+ years only powered by a small coin battery up to the world's lowest latency supercomputers based on FPGA costing thousands of $ per chip. On the software side I use programming languages ranging from the lowest level languages like assembly or even below with VHDL up to really high level languages like Common Lisp.

I've always enjoyed mixing electronics design and higher level computer science and all that diversity probably gives me a different and original view on say computing and programming in general.

What's your job? Tell us about your company.

I'm the CTO of NovaSparks a startup I founded in 2008 to make ultra-low latency FPGA based supercomputers for the financial markets. BTW These things are really incredibly fast. For instance on 10Gb/s Ethernet market data packets coming from exchanges like the NASDAQ we process the IP/UDP/multicast network stack, extract the messages from the packets, parse/decode/filter/normalize those messages, maintain the indexed order book data structures, aggregate the price levels per stock, generate output messages and finally send them to a server through PCI-express or 10Gb/s Ethernet network stacks. The nice thing is that we do all that fully pipelined at a rate of one message every 12 nanoseconds! To have an idea of how fast it is, in 12 ns the light will only travel 3.6 meters (11.8 ft). Another way to view this performance is that the system can process 83 Millions of financial messages per second without any queuing.

As an aside it is interesting to note that the Domain Specific Language Compilers and various other tools written in Common Lisp have been key enabling factors for the creation of NovaSparks.

I'm also the CEO and CTO of Fractal Concept which is the company where we were developing that technology before starting NovaSparks but as NovaSparks has been using more than 100% of my time for the last years Fractal Concept has been less active with only the development and maintenance of the smart sensors going on.

Do you use Lisp at work? If yes, how you've made it happen? If not, why?

I've always used Common Lisp for most of my work and even when I need to use other programming languages (like VHDL for NovaSpark's FPGAs or javascript for web stuff) I generally use Common Lisp at least for a lot of related tasks like prototyping, designing and testing algorithms, extracting statistics, performing simulations, generating test data, analysing test runs.

The next step is very often to generate some or all the code in other languages by designing various domain specific languages (DSL) which will take care of the tedious aspects of programming in less powerful languages. I really like it when from a few 100s of lines written in a easy to use high level DSL we generate 10000 to 60000+ lines of very low level VHDL code saving months of development.

About that point I think I would even say that I'm mostly doing Language Oriented Programming by trying to abstract the domain specific knowledge into various domain specific languages with very different syntaxes like s-expressions, C like or other languages or even sometimes adding to the mix some GUI or data-based inputs. Then those DSLs would generate most if not all the application code in whatever language is needed be it VHDL, asm, C, javascript or Common Lisp.

What brought you to Lisp? What holds you?

A friend of mine gave me a version of Le_Lisp a version of Lisp used in the 80's by the French universities and engineering schools to teach high level programming concepts. At that time I was mostly programming in Z80 assembly language on a TRS80 and the straight jump from ASM to Lisp was quite a shock and an eye opener.

Since then I've used Common Lisp for countless projects ranging from a few hours of work to multi-years ones and I still find it awesome. Where else can you find a language providing such powerful and multi-paradigms features like CLOS, generic functions, the MOP, macros, closures, s-expressions, lambdas, an interactive REPL (Read Eval Print Loop), native compilation of applications, on the fly native compilation of generated code, the condition system, interactive live programming, real time live debugging of running software and more!

What's the most exciting use of Lisp you had?

I've got so many of them than picking only one would be difficult so here are a few of them:

• softscan: real time driving and data acquisition of automated non-destructive testing installations with real time 3D display (a first in 1995)
• my web application framework: Automatic generation of really complex web applications (the whole stuff from the HTML/javascript front-end to the server back-end). It has been fully Ajax-based with dynamic modification of the displayed pages without reloading the page. This seems obvious nowadays but it was also a first in 2000 and IIRC the term "Ajax" was only invented 5 years later.
• hpcc: The awesome DSL to VHDL compiler. In many aspects VHDL is the complete opposite of Common Lisp. It's a hardware description language used to program FPGA and it deals with the lowest possible programming level with data types like signals, clocks, and bits. Programming at that level is really tedious, time consuming and verbose so it's really a relief to be able to generate tens of thousands of lines of highly optimized VHDL code from just a few hundred lines of some high level Domain Specific Language.
• cl-pdf/cl-typesetting: Being able to generate the first PDF files from scratch in only 107 lines of Common Lisp was an Haha moment.

What you dislike the most about Lisp?

The language itself is somewhat good enough and anyway Common Lisp makes it really easy to change most of itself to add the new and cool stuff or ideas of the day.

In fact what I dislike about Lisp is outside the language and more related to the (mis)perception that people have about it. Having almost everytime to justify its use and sometimes even to fight to be able to use it is somewhat annoying and tiresome.

Of course, Lisp is not for everybody but this is not a reason to have nobody using it. In fact I view Lisp as some kind of amplifier which will give awesome things when used by brilliant developers but will end up giving an incredible mess when used by people without any clues about what they are doing. That's one aspect that makes Lisp very different from other languages which are especially designed to try to normalize and average what people can do with them.

Describe your workflow, give some productivity tips to fellow programmers.

I obviously use emacs and all the nice stuff that work with it like slime, org-mode, magit and lots of other packages. I switched from subversion (svn) to git for all my projects and I now use git mostly form emacs with magit.

In general I have several instances of Lispworks running as standalone apps on my laptop but connected to Slime through M-x slime-connect rather than being started by slime. I do a lot of exploratory programming and interactively play with the code while I write it and if I have to optimize some code I very often use #'disassemble.

About my Lisp coding style I really do like generic functions, CLOS and the MOP. As mentioned earlier I try to generate as much of the code as possible by using macros in simple cases and full blown DSLs in more complex ones. Sometimes I do not dislike making some premature optimizations when I know that speed will be important for some project. BTW when speed matters I like to generate and compile code on the fly when it's useful (and possible) and try to generate really optimized code. It's always cool when you have Common Lisp applications running much faster than C++ ones.

I also refactor a lot. Generally when I start on some new stuff I try to make a first version that works well enough but then once it's done or generally after some time I have some cool ideas to make something much better. At that point I'm really happy that Common Lisp makes refactoring very easy thanks to optional and key args, macros and generic functions with multiple dispatch because all that enables me to make even very deep modifications very easily. I really find those Common Lisp features make software very resilient to code modifications.

What are the advantages of using Lisp in the HPC field? What are the drawbacks? Are you happy with your technology choice?

The HPC field is huge and I can only talk about the small corner of it I know which is the ultra-low latency processing of vast amounts of data we do in NovaSparks. For that the various DSL compilers generating VHDL code have really been a key enabling factor. Programming FPGAs is notoriously difficult and time consuming and this is the major factor limiting the use of reconfigurable computing in the HPC field. The use of those DSL compilers has made it possible to use those FPGA on a more practical basis for processing financial data.

BTW I'm looking for other HPC domains in which those DSL VHDL compilers could be used so feel free to contact me if you have some ideas.

If you had all the time in the world for a Lisp project, what would it be?

Again that's a difficult choice. Speaking about pure Lisp projects I've been willing for a long time to clean up and modernize my web app framework before releasing it as open-source so maybe that could be a good project to start.

Otherwise as mentioned above, I'm looking for possible applications and opportunities of leveraging the DSL => hardware compilers and the FPGAs around some Big Data processing. I have a few ideas but nothing specific for now.

Anything else I forgot to ask?

A conclusion? (Everybody wants a conclusion.) So here is mine:

Common Lisp is Awesome! It is much easier nowadays to use it thanks to all the projects and libraries that Quicklisp makes available. If you do not know Common Lisp then learn it and this will make you a better programmer anyway even if you do not use it directly after.

submit

Lisp Hackers: Vladimir Sedach

Vladimir Sedach is an active open-source Common Lisp developer and proponent, as well as a computing philosopher to some extent. At his carcaddar blog he writes about decentralized social networks, forgotten bits of computer history and, surely, Lisp. He is the maintainer or originator of a few open-source libraries like parenscript and Eager-Future2, and works on Vacietis C-to-Lisp compiler, which he describes in more detail in the interview. Together with Andrey Moskvitin they were the driving force behind 2012 cliki update effort (see cliki2).

Tell us something interesting about yourself.

In 2012 my best friend and I rode our bicycles across the USA.

What's your job? Tell us about your company.

Right now I work at ZestFinance in Hollywood. We're a relatively new company that's helping the underbanked receive access to credit on more reasonable terms than otherwise obtainable, by using machine learning. The only thing bad about my job is that I get so focused on programming at work that I don't have any desire to hack on Free Software projects when I come home, so a lot of my own projects are currently badly neglected.

Do you use Lisp at work? If yes, how you've made it happen? If not, why?

I've used Lisp for new commercial projects where people trust me with the technology choices. I've also come in to work on existing Lisp projects. I have used Lisp for one-off tasks at "non-Lisp" companies, but I've never started a Lisp project at a company that wasn't using Lisp already. Most computer programmers tend to make technical decisions based on cliches they read about on the Internet, and unfortunately I don't know the cure for being dumb.

What brought you to Lisp? What holds you?

As a teenager I got interested in computer graphics, and came across this really cool 3d graphics program called Mirai from Nichimen Graphics. Mirai was written in Common Lisp, and I read more about Lisp in the Slashdot interview with Kent Pitman, and started reading SICP based on Kent's recommendation. By the second chapter computer programming had finally made sense to me, and by the third I had decided to study mathematics in university.

As an aside, Mirai is directly descended from the S-Graphics software from Symbolics. Not many people know this, but Symbolics was actually the second producer of commercially available 3d computer animation software (the first was Wavefront). S-Graphics was a complete modeling, animation, and painting system, and it was all written in Lisp in the mid 1980s.

Common Lisp is still the best programming language I've come across. There is the feeling of freedom. No one is telling you what patterns or types to use. You can always just write code in a way that is most appropriate for what you're currently doing.

What's the most exciting use of Lisp you had?

Working with Daniel Gackle on Skysheet. We did some very awesome things with Parenscript.

What you dislike the most about Lisp?

No one has yet invented a good way to write "one-liners" in Lisp. I would love to replace my Unix shell with a Lisp REPL someday.

Among the software projects you've participated in what's your favorite?

Vacietis, for the sheer amount of hacks per line of code, and for the "I proved them wrong" factor. It was during the development of Vacietis that I came up with my current programming philosophy: "when stuck, do the stupidest thing possible"

Tell us about Vacietis: your vision for it, the project's progress and roadmap, what's lacking?..

Vacietis was originally intended to be a translator for a subset of C code to Common Lisp. I discussed the idea for Vacietis a few times online before starting to code, and people generally thought it wouldn't be doable. Scott Burson, who wrote the Zeta-C compiler for Lisp Machines in the 1980s, told me it would take at least a year of full-time of work.

As I worked on Vacietis, I realized that adding more and more of the "advanced" C functionality was actually easy. First came the C preprocessor (which is implemented as part of the Common Lisp readtable that also parses the C code), then large patches of the C standard library, and then one day Brit Butler came along and sent me a one-page patch that actually used Vacietis as a stand-alone C compiler! I hadn't even realized the project had gotten to that phase. The compiler comes as the "vacietis.vcc" ASDF system as part of Vacietis.

Some big things that need to be done are struct call-by-value, pointer scaling, arguments to main(), some libc stuff, setjmp, and making VCC produce linkable Lisp "object" files (fasls) for the different implementations. I would also like to change the pointer representation to be a fixnum offset into a sparse array (right now pointers are represented by structures that look like <offset, array>).

Overall, I am amazed by how much progress Vacietis has made given how little time I spent on it. I am now convinced that Common Lisp is mostly a superset of C, and have a newfound appreciation for gotos and PROG.

If you had all the time in the world for a Lisp project, what would it be?

A single-address space Common Lisp operating system based on capabilities (Jonathan Rees wrote a dissertation on doing this in Scheme in 1995) and a virtualized package system. I really like Azul Systems' hack of using the EPT/RVI virtualized page tables as a hardware read barrier for real-time garbage collection, and with a single-address space operating system I think you can do the same thing on hardware with a regular MMU.

If you follow the steps of the Viewpoints Research Institute's Fundamental New Computer Technologies project and keep the system as simple as possible, it should be a surmountable amount of work to realize a somewhat working system.

Vacietis is actually the first step in the Common Lisp operating system project. I'd like to have a C runtime onto which I can port hardware drivers from OpenBSD with the minimal amount of hand coding. The way hardware drivers are written in OpenBSD (a set of patterns it borrows from NetBSD, where they originated and are colloquially known as "bus_dma") is very pleasant. Theo de Raadt was also the first well-known Free Software operating system developer to take a position against binary hardware drivers, and I respect him tremendously for that. Linus Torvalds doesn't care, and as a result it is now impossible to get drivers for any of your ARM devices, even though 99% of them run Linux. OpenBSD will continue to have great, stable Free Software device drivers that are easily portable for different hardware architectures and to the other BSD-derived operating systems. I hope OpenBSD's model of Free Software hardware drivers catches on more widely.

Describe your workflow, give some productivity tips to fellow programmers.

I tend to design software systems in advance only at the level of the domain. I find that programmers who try to come up with APIs or draw class diagrams ahead of starting to code tend to write very poor code.

I rely heavily on interactive programming for doing mundane tasks, and since most programming time is spent dealing with mundane things, I spend most of my time in the REPL. Fortunately the Common Lisp REPL is the best programming environment I have come across. Things like the Rails console don't even come close. The only comparable environment is the Unix shell.

It's also very easy to turn Common Lisp REPL code into unit tests, which I tend to do a lot. That is something that's very hard to do with object-oriented code, which is why idiotic things like dependency injection and Test-Driven Development have to be invented.

For difficult problems, it's always better to step back from the keyboard and just think about your code. Hacking around in the debugger is usually a waste of time (the only exception is when you're having data structure issues, but then technically you're in the object inspector). I mostly tend to debug with print statements.

The best productivity tip I've come across is the "Seinfeld technique" that I learned about from reading Hacker News. It involves doing something, no matter how small, on your project every single consecutive day, without any gaps or interruptions. Apparently Jerry Sienfeld uses a big calendar and tries to mark up large "runs" of consecutive days on it. That really keeps you focused.

One thing I try to focus on in my code is giving unambiguous, unique (ie, easily grep-able) names to symbols. That makes it easy to go back to old code and quickly figure out what is going on. Common words like "status," "mapping," etc. make terrible names unless you qualify them.

submit

Lisp Hackers: John Fremlin

John Fremlin has created a couple of very performant Common Lisp programs beating on some microbenchmarks the fastest similar software written in any other language, including C: the teepeedee2 dynamic webserver, that managed to break the c10k record on a single core machine, and cl-irregex regex library. Working at MSI in Japan he also had written an object persistence DB for CL manardb. Besides, he writes interesting blogs on topics of software optimization, programming languages and technology in general.

Tell us something interesting about yourself.

I've been to more than eighty countries; I want to go everywhere!

What's your job? Tell us about your company.

I work at Facebook on the growth team, on data-driven improvements to the sign-up flows.

Do you use Lisp at work? If yes, how you've made it happen? If not, why?

I used to at msi.co.jp. It is a Japanese consultancy based in Tokyo called originally Mathematical Systems Institute. Mr Kuroda leads the Lisp group there and I think it has hovered around five or six people over many years. He's done a great many very interesting projects for a range of companies over the years: for example a crash-test data inspection tool for a big Japanese car company, text mining, graph visualisation and so on. I worked primarily on building up a visualisation and mapping of a very large set of routers for the world's biggest telecoms, which led to the creation of manardb.

I really enjoyed working for Mr Kuroda and I'm sorry I had to leave for personal reasons. There were always many very fascinating problems around — with great people to discuss them and find solutions. It was a very stimulating workplace!
At Facebook, I use PHP, Python, C++, Java and miscellaneous things. I think we would all be better off if we hadn't balkanised the different systems that we program for — and Lisp is one of the few programming languages with the flexibility to serve in all these roles.

What brought you to Lisp? What holds you?

My initial programming was following Michael Abrash's graphics books and building on his ideas, by doing things like runtime native code generation for drawing dynamically generated bitmaps efficiently. This is not so interesting for modern processors as they have good branch prediction but the idea of code generation stuck with me and Lisp is one of the few programing languages that makes this easy and efficient.

I appreciate the intellectual coherence of Lisp, and its sensible approach to numeric computations. In terms of using it today, I feel that Common Lisp has an advantage over many other programming languages in that it has multiple mature independent implementations. Running on multiple compilers tends to greatly increase the quality of a program in my opinion, as the code is exposed to different static analyses.

What's the most exciting use of Lisp you had?

I helped someone use Lisp for an automated trading project.

What you dislike the most about Lisp?

In trying to make efficient code one ends up fighting against the compiler and the runtime system and most of the time is spent in coming up with clever ways to circumvent and outwit both. This is not a good use of resources, and means that it usually makes more sense to start with C++.

Tell us about your approach(es) to optimizing Common Lisp code (and maybe code optimization in general)?

The most important thing is to try to hold in your head an understanding of where the program is going to spend time. Profilers can be misleading and inaccurate, and it is sometimes difficult to get representative workloads to profile. I think their main utility is in confirming that there is no sloppy mistake (in Lisp, typically, consing accidentally) that prevents you from achieving the natural performance of your approach.

Complexity analysis in terms of computation, network usage, disk accesses and memory accesses is a first step as obviously if you can improve the asymptotic usage of a bottlenecked resource, you will very likely do much better than trying to tweak some little detail. The second step is to try to characterize interactions with caches and, in Lisp, garbage collection, which is pretty tricky.

Among the software projects you've participated in what's your favorite?

I think the one I enjoyed most was an embedded H.264 decoder in 2005. This was for the VideoCore, a really wonderful CPU architecture that could deal with parallelizable problems incredibly efficiently if programmed correctly. It would have been awesome to use Lisp for it!

If you had all the time in the world for a Lisp project, what would it be?

I wish there were Lisp bridges to other runtime systems (Java, Android, Objective C, Perl, Python, C++, R, etc.) so that the libraries and tools for each could be leveraged efficiently in Lisp and vice versa. That would mean being able to call Java code and handle Java objects in Lisp, for example -- perhaps initially by spinning up a Java implementation in a separate process running a CL-SWANK style interface.

I really don't think this would be that difficult and it would make a huge difference to the convenience of building programs in Common Lisp!

Describe your workflow, give some productivity tips to fellow programmers.

I use emacs and I have a bunch of elisp code that I keep meaning to publish!

submit

Lisp Hackers: Slava Akhmechet

Slava Akhmechet published several enlightening essays at defmacro.org, of which one I often recommend to people, interested in learning about Lisp: The Nature of Lisp. He also created a continuation-based Lisp web-framework - Weblocks, backed by a delimited continuations library cl-cont. Other then that he is a co-founder of a startup company RethinkDB, of which he tells a bit in the interview.

Tell us something interesting about yourself.

For a long time I thought that human achievement is all about science and technology. In the past few years I realized how misled I was. Hamlet is as important an achievement as discovering penicillin. I wish I'd figured out earlier that science, for all its usefulness, is very limiting if one adopts it as an article of faith.

What's your job? Tell us about your company.

I'm a founder at RethinkDB. We spent three years building a distributed database system that we're about to open source and release in the next two weeks. The system allows people to easily create clusters of machines, partition data in a click of a button, and run advanced, massively parallelized, distributed queries using a very comfortable query language we've designed. The product is really delightful to use — we were just playing with it today to analyze census data for the upcoming presidential election in the U.S. and using it to play with the data is a real joy. I'm very proud of what we've done here — I hope it will make lots of people's jobs easier and let them do things they couldn't have done before.

My job here is to do the most important thing at any given time. Sometimes it means fixing bugs, sometimes it means demoing the product to customers, and sometimes it means driving to buy supplies so our developers can get their jobs done.

Do you use Lisp at work? If yes, how you've made it happen? If not, why?

We don't use Lisp, but much of our software is built on ideas borrowed from Lisp. We don't use it because we needed low level control — most of the code is written in C++, even with some bits of assembly. But we've borrowed an enormous number of ideas from Lisp. In fact, if we weren't Lispers, we would have built a very different (and I think significantly more inferior) product.

What brought you to Lisp? What holds you?

A guy named bishop_pass on gamedev.net forums about fifteen years ago. He was a really good advocate and I respected his opinions because of other subjects, so I decided to check Lisp out. I enjoyed it immensely, and spent years hacking in it. Today the only Lisp I still use is Emacs Lisp. I honestly don't know if I'll program in Lisp again (other than for fun, of course), but the ideas behind it will be with me forever.

What's the most exciting use of Lisp you had?

I built cl-cont — a macro that converts Lisp code to continuation passing style. I honestly think I learned more about programming from that experience than from anything else I've done before or after.

What you dislike the most about Lisp?

Probably the arrogance of the community that surrounds it. Knowing Lisp certainly doesn't make one a better person, nor even necessarily a better programmer.

Among the software projects you've participated in what's your favorite?

Definitely RethinkDB. We took a really complex subject (real-time distributed systems) and made them extremely accessible and super-easy to use. I love the product both because we made the user experience a joy, and because of the really advanced technology that goes inside to make that happen (from low-level assembly hacks, all the way up to abstract mathematics).

If you had all the time in the world for a Lisp project, what would it be?

I'd want to build my own Lisp dialect. I know, I know, it's been done to death, there is no need to do it, and it only hurts the community, but in the presence of infinite time, it's just too much fun not to do.

Describe your workflow, give some productivity tips to fellow programmers.

The most important thing I learned on productivity is this Alan Kay quite — "Perspective is worth 80 IQ points." You could be the most productive person in the world, but it won't make the slightest bit of difference if you're pointing your talents in a direction that isn't useful to other people. If you're talented, your gift is precious and your time is limited. Learn how to direct your talents, it will be the most important thing you do.

You're currently a co-founder of a startup company RethinkDB, which went through YCombinator. As an insider of the startup ecosystem, in your opinion, what are the areas for Lisp use in startups nowadays with the biggest potential upside and why?

This isn't a popular stance in the Lisp community, but I think that today Lisp is mostly valuable as an education tool, as a means of thinking, and as an engine of ideas. It's very important for that. But as far as practical use goes, there are better options today.

submit

Lisp Hackers: François-René (Faré) Rideau

François-René Rideau works at ITA Software, one of the largest employers of lispers, which was acquired by Google a year ago. While at ITA he stepped up to support and improve ASDF, the system definition facility, that is at the core of Lisp package distribution. He's also the co-author of the recently published Google Common Lisp Style Guide, which as well originated at ITA.


He's also an active writer: both of code and prose. He's thoughts and articles can be found on twitter, Facebook, Google+, Livejournal, and his site.

Tell us something interesting about yourself.

I like introducing myself as a cybernetician: someone interested in the dynamic structure of human activities in general.

Programming languages and their semantics, operating systems and reflection, persistence of data and evolution of code, the relation between how programmers are organized and what code they produce — these are my topics of immediate professional interest. For what that means, see for instance my slides (improved) from ILC'09: "Better Stories, Better Languages" or my essay "From Creationism to Evolutionism in Computer Programming".

However I'm also interested in cybernetics as applies to Civilization in general, past, present and future. See for instance my essay "Identity, Immunity, Law and Aggression on the Rapacious Hardscrapple Frontier" or my writings about Individual Liberty and the basic principles of Economics

Last but not least, I was recently married to my love Rebecca Kellogg, with whom I have since had a daughter Guinevere Lý "Véra" Kellogg Rideau (born last May). This gives me less free time, yet somehow made me more productive.

What's your job? Tell us about your company.

For the last 7 years or so, I have been working at ITA Software, now part of Google Travel. I have been working on two servers written in Lisp, at first briefly on QPX the low (air)fare search engine behind Orbitz and Google Flights then mostly on QRes, a reservation system now launched with Cape Air. These projects nowadays each count about half a million lines of Common Lisp code (though written in very different styles), and each keep growing with tens of active developers.

I suspect that my login "fare" (at itasoftware) was a pun that played in favor of recruiting me at ITA; however, it wasn't available after the Google acquisition, so now I'm "tunes" (at google), to remind myself of my TUNES project.

At ITA, I have been working mostly on infrastructure:

• how to use better compilers (moving from CMUCL to SBCL, CCL),
• how to build, run and test our software,
• how to maintain the free software libraries we use and sometimes write,
• how to connect QRes to QPX and follow the evolution of its service,
• how to persist objects to a robust database,
• how to migrate data from legacy systems,
• how to upgrade our software while it's running, etc.

And debugging all of the above and more, touching many parts of the application itself along the way.

I think of my job at ITA so far as that of a plumber: On good days, I design better piping systems. On bad days, I don gloves and put my hands down the pipes to scrub.

Since you're mentioning me as working at ITA and on ASDF, I suppose it is appropriate for me to tell that story in full.

In building our code at ITA, we had grown weary of ASDF as we had accumulated plenty of overrides and workarounds to its unsatisfactory behavior. Don't get me wrong: ASDF was a massive improvement over what existed before (i.e. mk-defsystem), making it possible to build and share Common Lisp software without massive headaches in configuring each and every library. We have to be grateful to Dan Barlow indeed for creating ASDF. But the Common Lisp ecosystem was dysfunctional in a way that prevented much needed further improvements to ASDF. And so I started working on a replacement, XCVB.

Now, at some point in late 2009, I wrote a rant explaining why ASDF could not be saved: "Software Irresponsibility". The point was that even though newer versions of ASDF were written that slowly addressed some issues, every implementation stuck to its own version with its own compatibility fixes; no vendor was interested in upgrading until their users would demand upgrades, and users wouldn't rely on new features and bug fixes until all vendors upgraded, instead caring a lot about bug-compatibility, in a vicious circle of what I call "Software Irresponsibility", with no one in charge, consensus required for any change, no possible way to reach consensus, and everyone discouraged.

However, I found a small flaw in my condemnation of ASDF as unsalvageable: if, which was not the case then, it were possible to upgrade ASDF from whichever version a vendor had installed to whichever newer version you cared for, then ASDF could be saved. Users would be able to rely on new features and bug fixes even when vendors didn't upgrade, and vendors would have an incentive to upgrade, not to stay behind, even if their users didn't directly demand it. The incentive structure would be reversed. Shortly after I wrote this rant, the current ASDF maintainer stepped down. After what I wrote, I felt like the honest thing to do was to step forward. Thus, I started making ASDF self-upgradable, then massively improved it, notably making it more robust, portable, and easy to configure — yet fully backwards compatible. I published it as ASDF 2 in 2010, with the help of many hackers, most notably Robert Goldman, and it has quickly been adopted by all active Common Lisp vendors.

You can read about ASDF and ASDF 2 in the article I wrote with Robert Goldman for ILC 2010: "Evolving ASDF: More Cooperation, Less Coordination". I'm also preparing a talk at ILC 2012 where I'll discuss recent enhancements. I have to admit I didn't actually understand the fine design of ASDF until I had to explain it in that paper, thanks to the systematic prodding of Robert Goldman. Clearly explaining what you're doing is something I heartily recommend to anyone who's writing software, possibly as a required step before you declare your software complete; it really forces you to get the concepts straight, the API clean, and the tests passing. That also did it for me with my more recent lisp-interface-library, on which I'm presenting a paper at ILC 2012: "LIL: CLOS reaches higher-order, sheds identity, and has a transformative experience".

One double downside of ASDF 2 is that it both took a lot of resources I didn't put in XCVB, and made for a much better system for XCVB to try to disrupt. It isn't as easy anymore to be ten times better than ASDF. I still hope to complete XCVB some day and make it good enough to fully replace ASDF on all Common Lisp platforms; but the goal has been pushed back significantly.

Now one important point that I want to explicitly stress is that the problem with ASDF was not a strictly technical issue (though there were many technical issues to fix), nor was it strictly a social issue; it was an issue at the interface between the social and the technical spheres, one of how our infrastructures and our incentives shape each other, and what kind of change can bring improvement. That's the kind of issues that interest me. That's why I call myself a cybernetician.

Do you use Lisp at work? If yes, how have you made it happen? If not, why?

I've made it happen by selection. I applied at ITA Software precisely because I knew (thanks to the Carl de Marcken article published by Paul Graham), that the company was using Lisp to create real-world software. And that's what I wanted to do: create real-world software with a language I could use without wanting to kill myself every night because it is turning me into a pattern-expanding machine rather than a human involved in thinking and using macros as appropriate.

"I object to doing things that computers can do." — Olin Shivers

Yet, in my tasks as a plumber, I have still spent way too much time writing shell scripts or Makefiles; though these languages possess some reflection including eval, their glaring misdesign only lets you go so far and scale so much until programs become totally unmanageable. That's what pushed me over the years to develop various bits of infrastructure to do as much of these things as possible in Lisp instead: cl-launch, command-line-arguments, philip-jose, xcvb, asdf, inferior-shell.

Interestingly, the first and the last, cl-launch and inferior-shell, are kind of dual: cl-launch abstracts over the many Lisp and shell implementations so you can invoke Lisp code from the Unix shell; it is a polyglot lisp and shell program that can manipulate itself and combine parts of itself with user-specified Lisp code to produce an executable shell script or a dumped binary image; I sometimes think of it as an exercise in "useful quining". inferior-shell abstracts over the many Lisp and shell implementations so you can invoke Unix shell utilities from any Lisp implementation, remotely if needs be (through ssh), and with much nicer string interpolation than any shell can ever provide; it is a classic Lisp library notably available through Quicklisp. With the two of them, I have enough Unix integration that I don't need to write shell scripts anymore. Instead, I interactively develop Lisp code at the SLIME REPL, and have a shell-runnable program in the end. That tremendously improved my quality of life in many situations involving system administration and server maintenance.

What brought you to Lisp? What holds you?

My first introduction to Lisp was in high-school, in using the HP RPL on my trusty old HP 28C (eventually upgraded to a HP28S, with 32KB of free RAM instead of 4KB!). When I became student at Ecole Normale Supérieure, I was taught Caml-light by xleroy himself, I learned to use Emacs, and I met Juliusz Chroboczek who introduced me to Scheme and Common Lisp, continuations and SICP. Finally, during my vain efforts to gather a team to develop an operating system based on a higher-level language as part of the TUNES project, I have been introduced to Lisp machines and plenty of other interesting concepts.

I use Lisp because I couldn't bear to program without higher-order functions, syntactic abstraction and runtime reflection. Of all Lisp dialects, I use Common Lisp mainly because that's what we use at work; of course a large reason why we use it at work is because it's a good language for practical work. However, frankly, If I were to leave ITA (by Google), I'd probably stop using Common Lisp and instead use Racket or Maru, or maybe Factor or Slate, and try to bootstrap something to my taste from there.

What's the most exciting use of Lisp you had?

I remember being quite exhilarated when I first ran the philip-jose farmer: it was a server quickly thrown together by building green-threads on top of arnesi's (delimited) continuation library for CL. With it, I could farm out computations over a hundred servers, bringing our data migration process from "way too slow" (weeks) to "within spec" (a few hours). It's impressive how much you can do in Lisp and with how little code!

While I released the code in philip-jose, it was never well-documented or made user-friendly, and I suspect no one ever used it for real. This unhappily includes ITA, for my code never made it to production: I was moved to another team, our customer went bankrupt, and the new team used simpler tools in the end, as our actual launch customer was 1/50 the size of our first prospect.

What you most dislike about Lisp?

For Lisp in general, I would say the lack of good ways to express restrictions on code and data. Racket has been doing great work with Typed Racket and Contracts; but I'm still hoping for some dialect with good resource management based on Linear Logic, and some user-extensible mechanism to define types and take advantage of them.

For Common Lisp in particular, though I do miss delimited continuations, I would say that its main issue is its lack of modularity. The package system is at the same time low-level and inexpressive; its defsystem facilities are also lacking, ASDF 2 notwithstanding; up until the recent success of Zach Beane's Quicklisp, there wasn't a good story to find and distribute software, and even now it's still behind what other languages have. This is part of a vicious circle where the language attracts and keeps a community of developers who live happily in a context where sharing and reusing code is relatively expensive (compared to other languages). But things are getting better, and I have to congratulate Zach Beane once again for Quicklisp. I believe I'm doing my small part.

Among software projects you've participated in what's your favorite?

I unhappily do not have a great history of success in software projects that I have actively participated in.

However, I have been impressed by many vastly successful projects in which I had but a modest participation. In the Linux kernel, the Caml community, the Racket community, (QPX and QRes at work might also qualify but only to lesser degrees), there were bright people unified by a common language, by which I mean not merely the underlying computer programming language, but a vision of things to come and a common approach to concepts: not just architecture but architectonics. Another important point in these successful projects was Software Responsibility (as contrasted to the previously discussed Software Irresponsibility): there is always someone in charge of accepting or rejecting patches to any part of the system. Patches don't linger forever unapplied yet unrejected, so the software goes forward and the rewarded contributors come back with more and/or better patches. Finally, tests. Lots of them. Automatically run. All the time. Proofs can do, too, though they are usually more expensive (now if you are going to do testing at the impressive scale of sqlite, maybe you should do proofs instead (see CPDT). I discovered, the hard way, that tests (or proofs) are the essential complement to programs, without which your programs WILL break as you modify them.

If you had all the time in the world for a Lisp project, what would it be?

I would resurrect TUNES based on a Linear Lisp, itself bootstrapped from Racket and/or Maru.

Describe your workflow, give some productivity tips to fellow programmers.

First, think hard and build an abstract model of what you're doing. Guided by this understanding of where you're going, code bottom up, write tests as you do, and run them interactively at the SLIME REPL; make sure what you write is working and passing all tests at all times. Update your abstract model as it gets pummeled into shape by experience. Once you've got the code manually written once or twice and detect a pattern, refactor it using macros to automate away the drudge so the third time is a piece of cake. Don't try to write the macro until you've written the code manually and fully debugged it. Never bother with low-level optimization until the very end; but bother about high-level optimization early enough, by making sure you choose proper data structures.

Unhappily, I have to admit I am a serial under-achiever. I enjoy thinking about the big picture, and I like to believe I often see it better and further than most people; but I have the greatest trouble staying on track to bring about solutions: I have so many projects, and only one life to maybe complete a few of them! The only way I can actually get a few things done, is to decompose solutions into small enough steps such that I can keep focused on the next one and get it done before the focus goes away.

A year ago Google bought ITA, which was, probably, the largest Lisp company recently. What were the biggest upsides and drawbacks of using Lisp on the scale of ITA? Does Lisp have a future inside Google?

On the upside, we certainly have been able to write quite advanced software that we might not have otherwise managed. A million lines of Lisp code, including its fair share of macros and DSLs, would be so many more million lines of code without the syntactic abstraction made possible by Lisp. However hard and expensive it was with Lisp, I can only imagine how many times worse it would have been with anything else.

At the top of the tech bubble in 2008, we had over fifty Lisp programmers working just on QRes, gathered at an exponential rate over 3 years. That's a lot. We didn't yet have good common standards (Jeremy Brown started one, later edited by Dan Weinreb; I recently took it over, expanded it, merged it into the existing beginning of a Google Common Lisp Style Guide and published it), and it was sometimes hard to follow what another hacker wrote, particularly if the author was a recently hired three-comma programmer. But with or without standards, our real, major, problem was with lack of appropriate management.

We were too many hackers to run without management, and none of our main programmers were interested in becoming managers; instead managers were parachuted from above, and some of them were pretty bad: the worst amongst them immediately behaved like empire-building bullies. These bad managers were trying to control us with impossibly short, arbitrary deadlines; not only did it cause overall bad quality code and morale burnout, the renewing of such deadlines quarter after quarter was an impediment to any long-term architectural consideration for years. What is even worse, the organization as setup had a lot of inherent bad incentives and created a lot of conflicts, so that even passable managers would create damage, and otherwise good engineers were pitted against each other one two sides of absurd interfaces, each team developing a lot of scar tissue around these interfaces to isolate itself from the other teams. Finally, I could witness how disruptive a single bad apple can be when empowered by bad management rather than promptly fired.

I have had a lot of losing fights with QRes management at a time when, hanging on a H1B visa, I was too much of a coward to quit. Eventually, the bad people left, one by one, leaving behind a dysfunctional organization; and great as the people that manned it may have been, none was able or willing to fix the organization. Then finally, Google acquired us. There's a reason why, of two companies founded at about the same time, one buys the other and not the other way around: one grew faster because it got some essential things right that the other didn't. Google, imperfect as it necessarily is, gets those essential things right. It cares about the long term. It builds things to scale. It has a sensible organization. It has a bottom up culture. So far, things have only improved within QRes. Also, launching was also good in many ways. It makes us and keeps us real.

Lisp can be something of a magic tool to solve the hardest technical issues; unhappily it doesn't even start to address the social issues. We wasted a whole lot of talent due to these social issues, and I believe that in an indirect way, this is related to the lack of modularity in Common Lisp, as it fostered a culture of loners unprepared to take on these social issues.

So I'm not telling you this story just to vent my past frustration. There too I have a cybernetic message to pass on: incentives matter, and technical infrastructure as well as social institutions shape those incentives and are shaped by them.

As for the future of Lisp at Google, that million line of Common Lisp code ain't gonna rewrite itself into C++, Java, Python, Go, or even DART. I don't think the obvious suggestions that we should rewrite it were ever taken seriously. It probably wouldn't help with turnover either. But maybe, if it keeps growing large enough, that pile of code will eventually achieve sentience and rewrite itself indeed. Either that, or it will commit suicide upon realizing the horror.

Anything else I forgot to ask?

Ponies.

submit

Lisp Hackers: Daniel Barlow

Daniel Barlow was one of the most active contributors to the open source Lisp ecosystem, when its development took off in the early 2000s. Together with Christophe Rhodes he was the first to join SBCL hacking, after the project was started by William Newman. He also had created a lot of early Lisp web tools, like Araneida HTTP application server, and built on it the first version of cliki.net, which served the Lisp community for almost 10 years (the second version went live earlier in 2012). Studying Cliki source was a kind of zen experience for me, as it did so much, yet in a very simple way.


But his largest contribution is, probably, ASDF, regarding which, likewise Cliki, there are controversial opinions among Lisp programmers. And Dan explains his attitude in the interview.

In the mid 2000s his involvement with open-source Lisp gradually diminished, as he stopped working as a consultant and got a full-time job. Yet he remains fondly remembered in the community.

Tell us something interesting about yourself.

I don't do interesting. Um, improvise. Hacker, skater, cyclist, husband, father to a seven-month-old son as demanding as he is adorable, computing retro-grouch who uses Linux on the desktop.

I have a metal plate and some pins in my right forearm where I broke it a couple of months ago, inline skating in the Le Mans 24 hour relay event. I have now regained more or less complete range of motion in that hand and can advise anyone doing the event next year that the carpet in the pit boxes is unexpectedly treacherous when it's been waterlogged by a sudden thunderstorm.

Still, we came fifth in category, which makes me very happy.

What's your job? Tell us about your company.

I started a new job about three months ago, in fact. I'm now working at Simply Business in London, busily disrupting the business insurance market. Which is to say, writing web apps for the online sale of business insurance.

It's not quite as buzzwordy as it sounds, actually. Business insurance is traditionally sold by brokers, who are humans and therefore although really good at dealing with complex cases and large contracts where the personal touch is required, tend to be a trifle expensive for straightforward policies which could be much more economically sold online. The industy is ripe for disintermediation.

What brought you to Lisp?

A combination of factors around the time I was at university: the UNIX-Haters Handbook, which I bought to sneer at and ended up agreeing with; Caml Light, which I used in my fourth year project; Perl - specifically my horror to learn that it flattens (1,2,3,(4,5,6)) to (1,2,3,4,5,6) - yes, I know about references, but I think it's a bug not a feature that the sensible syntax is reserved for the silly behaviour - and meeting some people from Harlequin (as was) at a careers fair.

It took me another couple of years or so to find CMUCL - in fact, I think it was another couple of years or so before it was ported to the x86 architecture, so it wouldn't have done me much good if I had known about it earlier - but looking back I suppose that was where the rot set in.

Do you use Lisp at work? If yes, how you've made it happen? If not, why?

No, we're primarily a Ruby shop, with a sideline in large legacy Java app which we're working to replace. I think there've been a couple of uses of Clojure in hack days, but that's as far as it goes.

Why not? Well, apart from the point that I've only been there since July ... It's The Ecosystem, I suppose. Ruby as a language has pretty good support for OO paradigms and a whole bunch of free software libraries for doing web-related things: Ruby as a community is big on Agile and TDD and maintainable design. And it's at least possible (if not exactly easy in the current bubble) to engage a regular recruitment agent and task him with finding competent programmers who know it. I'm not saying Lisp is exactly bad at any of that, but it's at least questionable whether it's as good along all of those axes, and it's certainly not better enough to make the switch sensible.

What's the most exciting use of Lisp you had?

SBCL was probably one of the most fun projects I've ever worked on. Working with people who were mostly smarter than me or had better taste than me or both, on a project whose goal was to make it possible for people less smart than me to hack on a Lisp system. And context switching between the CL with all its high level features and (e.g.) Alpha assembly was a real kick - it's a bit like I imagine building a Lisp machine would be, except that the goal is achievable and the result is generally useful.

What you dislike the most about Lisp?

I don't really use it enough any more to react to that with the required levels of venom. I should probably say ASDF, everyone else does :-)

I guess if you force me to an answer, it'd have to be its disdain for the platform it lives on - take, for example, CL pathname case conversion rules. Whoever decided that Unix systems could reasonably be said to have a "customary case" had, in my view, not looked very hard at it.

As far as I can tell, you're currently mostly doing work in Ruby. What's the pros and cons of Ruby development compared to Lisp?

The transpose-sexps function in Emacs does nothing useful in Ruby mode. rails console is a poor substitute for a proper toplevel. Backtraces don't show the values of parameters and local variables. (Yes, pry helps a lot). And the garbage collector (in MRI, anyway) is sucky to the point that even 1990s Java GC could probably beat it in a fair fight.

On the other hand, libraries.

Here's an interesting thought experiment, though: there's a clear difference between the Lisp workflow where you change the state of your image interactively to get the code into working shape very quickly (and then later try to remember what it was you did) and the more scripted approach of test-driven development in Ruby where you put everything (code, test setup, assertions) in files that you reload from disk on each run. How would you meld the two to get repeatable and fast iterations? A lot of people are doing things like Spork (which forks your application for each test it runs, throwing the child state away after the test has run) but they never seem to me to be more than 80% solutions. My intuition is that you'd want to stick to a much more functional design and just make state a non-problem.

Among software projects you've participated in what's your favorite?

SBCL was a lot of fun, as I said earlier. ASDF is a candidate too, just because it must so obviously fill a need if people are still cursing it - as they seem to be - ten years later :-)

Describe your workflow, give some productivity tips to fellow programmers.

It's taken me the best part of three months to get this interview back to Vsevolod, I'm the last person anyone should be asking about workflow or productivity. :-)

Um. I've been doing a lot of TDD lately. Given that as recently as two years ago I was castigating it as a religion this might be seen as a capitulation or as a conversion, this might be perceived as a change of mind. What can I say? Actually, pretty much now what I said then: the value of TDD is in the forces it exerts on your design — towards modularity, functional purity, decoupling, all those good things - not so much in the actual test suite you end up with. Process not product. These days everyone thinks that's obvious, but back then it was either less widely known or less explicitly stated or else I was just reading the wrong blogs.

(Of course, the tendency in Lisp to write code interactively that can be tested ad hoc at the repl probably has a very similar effect on coupling and functional style. My personal experience is that TDD doesn't seem to be nearly as valuable in repl-oriented languages, but YMMV)

More generally: go home, do some exercise, get some sleep. Sleep is way underrated.

Anything else I forgot to ask?

Some day I will write an apology for ASDF.

Pedants will note that the word "apology" not only means "an expression of remorse or regret" but also "a formal justification or defence", and may infer from that and my general unwillingness to ever admit I was wrong that I'm not about to actually say I did a bad thing in writing it. Seriously, go find a copy of MK-DEFSYSTEM and try porting it to a Lisp implementation it doesn't support.

In 2002 I presented a paper at the ILC (about CLiki, not ASDF) that said essentially "worse is better than nothing", and - unless the "worse" has the effect of stifling a potential better solution from coming along later - I still stand by that

submit

Lisp Hackers: Luke Gorrie [+ his ECLM video]

Luke Gorrie is a proverbial hacker following his passion for programming to various places in the physical world, like Sweden or Nepal, or programming world, like Erlang, Forth, Lisp, Lua, or some other fringe language. And enjoying the process of exploration and meeting different people, while fiddling with computers, from OLPC to telecom equipment, working with world-famous technologists, including Joe Armstrong or Alan Kay, and, generally, doing whatever he likes in the programming world.

He was one of the main authors of SLIME in its early days. And recently he founded a Lisp networking startup Teclo Networks, the story of which (as of fall of 2011) he told at ECLM 2011. Here's the video, that he asked to hold off for some time due to business reasons, and only now it's posted online. Enjoy!



Luke's twitter account is @lukego

Tell us something interesting about yourself.

I enjoy exploring the world. I was born and raised in Australia (Brisbane), I've lived for many years in Sweden and become a Swedish citizen, and these days I'm extremely happy to be settling myself into Switzerland. I've spent a couple of years traveling continuously with just my backpack and unicycle and no home anywhere to go back to. I've found this interesting. You can find links to my exploits on my homepage.

I like to feel a bit out of my depth and to be "the new guy" who has a lot of catching up to do. This is why I so much enjoy learning new programming languages and visiting new programming communities so much: the feeling of having to think really hard about how to formulate even the most basic programs, just like when I was a kid, while other people do it so naturally.

What's your job? Tell us about your company.

I'm currently starting a new project called Snabb. It's too early to say very much about this yet, so I'll talk about the past.

I've had a few major jobs that have shaped my thinking. I worked in each one for about 3-5 years.

The first was Bluetail AB, the first Erlang startup company. I was hired by Joe Armstrong because I had enthusiasm pouring out of my ears and nostrils. I moved immediately to Stockholm in the middle of winter for this job -- I was 21 years old and I'd never left Australia or seen snow before. I learned a lot of things at Bluetail, besides practical matters like how to walk on ice. The programmers there were all way above my level and I was routinely stunned at the stuff they had done, like when Tobbe Törnqvist mentioned in passing that he'd written his own TCP/IP stack from scratch as a hobby project and that his dial-up internet connection uses his own home-brew PPP implementation. I used to roam the corridors at night borrowing tech books from people's shelves, there must have been a thousand books in the office.

Bluetail was bought by Alteon, who were bought by Nortel at the same time, and become a productive little product unit in a big networking company.

Next was Synapse Mobile Networks. This was an amazing experience for me: to switch from a big company to a small company and take care of everything from design to development to deployment to support by ourselves. Really getting to know customers and internalizing their needs and building the right solutions. The product is a device management system, which is a realtime database in a mobile phone network keeping track of which phone everybody is using and making sure all their services work. The whole thing was written in Erlang and BerkeleyDB, even with a from-scratch SS7 telecom networking stack in the end. I would routinely fly to a really interesting country -- Kazakhstan, Jordan, Russia, Algeria, you name it -- and spend a few weeks deploying the system and developing customizations on-site. Synapse was the first company in this market and they are still the market leader today. The system has by now configured approximately 1 billion actual mobile phones by sending them coded SMSes.

Synapse was also instructive in seeing how much a strong personality can shape a company. I'm still in awe of our fearless leader Per Bergqvist. What a guy, as they say on Red Dwarf.

The most recent is Teclo Networks. This is a company that I co-founded with friends from the SBCL community -- mostly drinking buddies from ECLM -- and friends from the telecom world. I served as CTO during the phase of finding the right problem to solve, building our series of prototypes and our real product, and finding our very first customers. I'm a Teclo-alumnus now, not actively working in the company, and: Wow, this was a really intense few years.

Teclo builds network appliances that optimize TCP traffic for cellular internet at about 20Gbps per server. The product speeds up the network, improves consistency, and globally eliminates buffer-bloat. The company is currently moving forward with a lot of momentum: we have Lispers like Juho Snellman, Tobias Rittweiler, and Ties Stuij currently deploying systems in real live networks all over the world. Go Teclo :-)

Do you use Lisp at work? If yes, how you've made it happen? If not, why?

I've mostly done Lisp hacking for my own pleasure on the side, but I've also used it quite a bit at work.

The first time was when I used Scheme at Bluetail. Specifically, I used Kawa to extend a Java application. I'm sure this raised some eyebrows amongst my colleagues but frankly I was having too much fun to really notice. Kawa is a great piece of software.

I wrote a bunch of Common Lisp networking code while reading books like TCP/IP Illustrated. This was a hobby project called Slitch and Netkit. I used this slightly in my work at Nortel to replicate a DoS against the Linux kernel that was crashing some of our appliances.

Teclo is very much a Lisp-hacker shop. In the first year or so we used Lisp for absolutely everything. We've written and deployed a prototype TCP/IP implementation written in Common Lisp (SBCL), wrote network analysis tools for cross-referencing and visualizing traffic captures (often working on traces that fill up a whole disk i.e. hundreds of gigabytes), and developed all of the operation-and-maintenance infrastructure in CL. These days Teclo uses C/C++ for the main traffic handling, R for statistical analysis, and Common Lisp for the rest -- mostly operation and maintenance and data visualization.

Among software projects you've participated in what's your favorite?

SLIME! This was wild fun. The project started when Eric Marsden, a CMUCL hacker, posted to #lisp his weekend hack to annotate individual S-expressions in an Emacs buffer with CMUCL compiler messages. His source files were slim.el and skank.lisp, after the Fatboy Slim song he was listening to at the time. I loved the idea so I started toying with it, renaming the files to slime.el and swank.lisp to make them easy to diff. I quickly posted my version to the cmucl-dev mailing list where Helmut Eller jumped right into it too. We created a Sourceforge project and quickly snowballed from there to over 100 contributors.

SLIME's mission was ultimately to replace ILISP as the standard Emacs mode for interacting with Common Lisp. ILISP worked by sending S-expressions between Emacs and Lisp via standard I/O and it had the unfortunate habit of getting stuck a lot. ILISP was also about 15 years old at that time (SLIME is catching up now at 8 years!) and really hard to work on due to the heavy use of reader conditionals in the source code, like #+cmucl #-lucid #+sbcl #-lispworks #+acl #-acl4.2 and so on.

I really enjoyed the feeling of working on a growing and thriving open-source project. Seeing the steady stream of new names appearing on our mailing list, getting patches from dozens of people, feeling good about positive feedback we received, working hard on negative feedback right away, and so on. Twas a really productive flow.

I think that writing development tools is also really satisfying because your users are your peer group: people you really look up to and respect and sometimes drink beer with. It's a great feeling to build stuff that they like to use.

Helmut Eller and I also had a really great working style. Very often I'd do some late-night hacking and check in a bunch of new functionality, which Helmut would then read through and think about and then thoughtfully rewrite in a simpler way. Then I'd see what he'd done, think about it, and rewrite it to be simpler again. And so on. This was a really pleasant and productive way of working. He is also an absolute magician when it comes to suddenly checking in what seems like a month worth of work that he did over the weekend. (Juho Snellman has this uncanny ability too.)

I hacked on SLIME from the beginning and up to version 1.0. Then I was engulfed by an Erlang startup. Here're some posts that I fished out of the mailing list archives to give a sense of the early days:

• SLIME is born
• Users!
• SLIME User Survey
• SLIME 1.0 release party :-)

What brought you to Lisp? What holds you?

My friend Darius Bacon brought me to Lisp (Scheme) by gently and persistently singing the praises of Abelson & Sussman back in the days when I was a teenager hacking Java. This book was a revelation for me: particularly the Digital Circuit Simulator. So I was a Scheme-lover for several years, but Darius also gently and persistently sang the praises of Norvig's Paradigms of AI Programming, which was another revelation to me, and made a Common Lisp convert of me.

What holds me to Lisp is the people. I love hanging out with Lisp hackers: I find that we're an unusually diverse community. How often do you attend a small conference where attendees are building nuclear defense systems, running intensive care wards, designing aeroplane engines, analysing Lute tablature, developing cancer drugs, writing FIFA's legal contracts, and designing their own microchips? Surely this describes few tech events other than Arthur & Edi's European Common Lisp Meeting :-).

What you dislike the most about Lisp?

I have a few stock rants that I'm tempted to rattle off -- fragmentation, threads, GC-phobia -- but honestly I doubt they are applicable these days. There have been so many improvements to SBCL and great developments like Quicklisp and so on.

I can say I'm personally disappointed about the missed opportunity for us to write Teclo's production traffic path in SBCL. Ultimately, the software has just a few microseconds' budget to process each packet, and can never spike latency by more than a millisecond. I don't know how to deliver that kind of performance in a high-level language like Lisp. So we fell back to C.

I'd also like to have embedded SBCL in the C program to take care of high-level work like slurping in configurations and spitting out statistics. But the SBCL runtime system is a bit heavyweight to make that practical. It gets in the way when you want to debug with strace, gdb, etc. So we wrote this stuff in C++ instead.

I'd have written a lot more Lisp code in recent years if I'd found good solutions to those problems. But at the end of the day it is C's niche to write lots of tiny state machines with extremely predictable performance characteristics, so I'm not especially shocked or disheartened. A language can't occupy every niche at once :-).

Describe your workflow, give some productivity tips to fellow programmers

I'm an incrementalist. I like to start from minimal running code, like (defun program () (print "Program 0.1")), and move forward in a long series of very small steps. I tend to choose designs that I know are too simple or too slow, because I enjoy the feeling of hitting their limits and knowing that I didn't prematurely generalize or optimize them. Then I fix them. I'd say that I'm much influenced by watching the development of Extreme Programming on WardsWiki in the 90s.

This isn't a hard and fast rule though. In Teclo I once spent a whole month writing a complex program without even trying to compile it once. This was a rewrite of the main traffic engine in C after having written a prototype in Lisp previously. This was a really fun way to work actually. I produced a tremendous amount of bugs in this style though and I wasn't smart enough to fix them. Christophe Rhodes did that part -- don't ask me how :-).

I do have a tip for getting into "the flow". It's a simple one: make a little TODO list of some features you want to hack, and take the laptop into the park away from the internet for an hour or two until they're done. This works every time for me.

Oh, and I highly recommend printing out and reading your programs. This is the best way that I know for improving their quality. This is why I'm a bit picky about things like the 80-column rule and the layout of functions within a file. I want to be able to print programs out and read them on paper from top to bottom. I wrote a program called pbook to help with this -- it's not a very good implementation though, with all those regexps, so I'd love if someone would make a much simpler one.

You have played around with so many languages, like Erlang, Lisp, Smalltalk & Lua. If you would design your own, how would it look like?

That's really hard to imagine. I'd have to find a reason that I needed a new programming language, and the details would probably follow from the problem I needed to solve.

I learn new languages mostly because I enjoy meeting new people and learning new ways of thinking. It's very seldom from any sense of dissatisfaction with previous languages I've used. My favourite languages are Common Lisp, Emacs Lisp, Forth, Erlang, Smalltalk, and C. So the best I can say is: those are the languages that I'd like to have designed.

P.S. Luke asked to give my warm thanks to John Q. Splittist for reading over these answers before I sent them to you (and for many other things!).
submit

Lisp Hackers: Peter Seibel

Peter Seibel has helped more people (including me) discover and become user of Lisp as probably noone else in the last decade with his Practical Common Lisp. Dan Weinreb, one of the founders of Symbolics and later Chief Architect at ITA Software, a succesfull Lisp startup sold to Google for around $1B in 2011, wrote, that their method of building a Lisp team was by hiring good developers and giving them PCL for two weeks, after which they could succesfully integrate under the mentorship or their senior Lisp people.

A few years after PCL Peter went on to write another fantastic programming book Coders at Work - here's my summary of it with the social network of Coders :)



Aside from being a writer he was and remains a polyglot programmer, interested in various aspects of our trade, about which he blogs occasionally. His code, presented in PCL, laid the foundation for a wide-spread CL-FAD library, which deals with filenames and directories (as the name implies), and more recently he created a Lisp documentation browser Manifest. Before Lisp Peter had worked a lot on Weblogic Java application server.

He's also active on twitter: @peterseibel

Tell us something interesting about yourself.

I’m a second generation Lisp programmer. My dad discovered Lisp when he was working at Merck in the 80s and ended up doing a big project to simulate a chemical plant in Lisp, taking over from some folks who had already been trying for quite a while using Fortran, and saving the day. Later he went to Bolt Beranek and Newman where he did more Lisp. So I grew up hearing about how great Lisp was and even getting to play around with some graphics programs on a Symbolics Lisp Machine.

I was also a childhood shareholder in Symbolics—I had a little money from some savings account that we had to close when we moved so my parents decided I should try investing. I bought Symbolics because my parents just had. Never saw that money again. As a result, for most of my life I thought my parents were these naive, clueless investors. Later I discovered that around that time they had also invested in Microsoft which, needless to say, they did okay with.

Oh, and something I learned recently: not only was Donald Knuth one of the subjects in my book Coders at Work, but he has read the whole thing himself and liked it. That makes me happy.

What's your job? Tell us about your organization.

A few months ago I started working half-time at Etsy. Etsy is a giant online marketplace for people selling handmade and vintage items and also craft supplies. I’m in the data group where we try to find clever ways to use data to improve the web site and the rest of the business.

Do you use Lisp at work? If yes, how you've made it happen? If not, why?

I always have a SLIME session going in Emacs for quick computations and sometimes I prototype things in Lisp or write code to experiment with different ideas. However, these days I’m as likely to do those things in Python because I can show my co-workers a sketch written in Python and expect them to understand it and I’m not sure I could do that with Lisp. But it makes me sad how slow CPython is compared to a native-compiling CL like SBCL. Usually that doesn’t matter but it is
annoying sometimes mostly because Python has no real excuse. The rest of my work is in some unholy mishmash of Scala, Ruby, Javascript, and PHP.

What brought you to Lisp? What holds you?

As I mentioned, I grew up hearing from my dad about this great language. I actually spent a lot of my early career trying to understand why Lisp wasn’t used more and exploring other languages pretty deeply to see how they were like and unlike Lisp. I played around with Lisp off and on until finally in 2003 I quit the startup I had been at for three years, which wasn’t going anywhere, with a plan to take a year off and really learn Common Lisp. Instead I ended up taking two years off and writing Practical Common Lisp.

At this point I use it for things when it makes sense to do so because I know it pretty well and most of my other language chops are kind of rusty. Though I’m sure my CL chops are rusty too, compared to when I had just finished PCL.

Did you ever develop a theory why Lisp isn’t used more?

Not one that is useful in the sense of helping it to be used more today. Mostly it seems to me to be the result of a series of historical accidents. You could argue that Lisp was too powerful too early and then got disrupted, in the Innovator’s Dilemma sense, by various Worse is Better languages, running on systems that eventually became dominant for perhaps unrelated reasons.

Every Lisper should read The UNIX-HATERS Handbook to better understand the relation between the Lisp and Unix cultures—Lisp is the older culture and back when the UNIX-HATERS Handbook was written, Unix machines were flaky and underpowered and held in the same contempt by Lisp geeks as Windows NT machines would be held by Unix geeks a few decades later. But for a variety of reasons people kept working on Unix and it got better.

And then it was in a better position than the Lisp culture to influence the way personal computing developed once micro computers arrived—while it would be a while before PCs were powerful enough to run a Unix-like OS, early on C was around to be adopted by PC programmers (including at Microsoft) once micros got powerful enough to not have to program everything in assembly. And from there, making things more Unix-like seemed like a good goal. Of course it would have been entirely possible to write a Lisp for even the earliest PCs that probably would have been as performant as the earliest Lisps running on IBM 704s and PDP-1s. My dad, back from his Lisp course at Symbolics, wrote a Lisp in BASIC on our original IBM PC. But by that point Lispers’ idea of Lisp was what ran on powerful Lisp machines, not something that could have run on a PDP-1.

The AI boom and bust played its role as well because after the bust Lisp’s reputation was so tainted by its failure to deliver on the over-promises of the Lisp/AI companies that even many AI researchers disassociated themselves from it. And throughout the 90s various languages adopted some of Lisp’s dynamic features, so folks who gravitated to that style of programming had somewhere else to go and then when the web sprang into prominence, those languages were well positioned to become the glue of the Internet.

That all said, I’m heartened that Lisp continues to not only be used but to attract new programmers. I don’t know if there will ever be a big Lisp revival that brings Lisp back into the mainstream. But even if there were, I’m pretty sure that there would be plenty of old-school Lispers who’d still be dissatisfied with how the revival turned out.

What's the most exciting use of Lisp you had?

I’m pretty proud of the tool chain I’ve built over the years while writing my two books and editing the magazine I tried to start, Code Quarterly. When I first started working on Practical Common Lisp I had some Perl scripts that I used to convert an ad-hoc light-weight text markup language into HTML. But after a little while of that I realized both that Jamie Zawinski was right about regexps and that of course I should be using Lisp if I was writing a book called Practical Common Lisp.

So I implemented a proper parser for a mostly-plain-text language that I uncreatively call Markup and backends that could generate HTML and PDF using cl-typesetting. When I was done writing and Apress wanted me to turn in Word files, I wrote an RTF backend so I could generate RTF files with all the Apress styles applied correctly. An Apress project manager later exclaimed over how “clean” the Word files I had turned had been. For editing Code Quarterly I continued to use Markup and wrote a prose diff tool that is pretty smart about when chunks of text get moved and edited a little bit.

What you dislike the most about Lisp?

I don’t know if “dislike” is the right term because the alternative has its own drawbacks. But I do sometimes miss the security of refactoring with more static checks. For instance, when I programmed in Java, there was nothing better than the feeling of knowing a method was private and therefore I didn’t have to look anywhere but in the one file where the method lived to see everywhere it could possibly be used. And in Common Lisp the possibilities for action at a distance are even worse than in some other dynamic languages because of the loose relation between symbols and the things they name. In practice that’s not actually a huge problem and some implementations provide package locks and so on, but it always makes me feel a bit uneasy to know that if I :use a package and then DEFUN a function with the name of an inherited symbol I’ve changed some code I really didn’t mean to.

From time to time I imagine a language that lets you write constraints on your code in the language yourself—kind of like macros but instead of extending the syntax your compiler understands, they would allow you to extend the set of things you could say about your code that the compiler would then understand. So you could say things like, “this function can only be called from other functions in this file” but also anything else about the static structure of your code. I’m not sure exactly what the API for saying those things would look like but I can imagine it being pretty useful, especially in larger projects with lots of programmers: you could establish certain rules about the overall structure of the system and have the compiler enforce them for you. But then if you want to do a big refactoring you could comment out various rules and move code around just like in a fully dynamic language. That’s just a crazy idea; anyone who’s crazy in the same way should feel free to take it and run with it and see if they get anywhere.

Among software projects you've participated in what's your favorite?

Probably my favorite software I ever wrote was a genetic algorithm I wrote in the two weeks before I started at Weblogic in 1998, in order to build up my Java chops. It played Go and eventually got to the point where it could beat a random player on a 5x5 board pretty much 100% of the time. One of these days I need to rewrite that system in Common Lisp and see if I can work up to a full-size board and tougher opponents than random. (During evolution the critters played against each other to get a Red Queen effect—I just played them against a random player to see how they were doing.)

Describe your workflow, give some productivity tips to fellow programmers

I’m not sure I’m so productive I should be giving anybody tips. When I’m writing new code I tend to work bottom up, building little bits that I can be confident in and then combining. This is obviously easy to do in a pretty informal way in Common Lisp. In other languages unit tests can be useful if you’re writing a bigger system though I’m often working on things for myself that are small enough I can get away with testing less formally. (I’m hopeful that something like Light Table will allow the easy of informal testing with the assurances of more strict testing—I’d love to have a development environment that keeps track of what tests go with what production code and shows them together and runs the appropriate tests automatically when I change the code.)

When I’m trying to understand someone else’s code I tend to find the best way is to refactor or even rewrite it. I start by just formatting it to be the way I like. Then I start changing names that seem unclear or poorly chosen. And then I start mucking with the structure. There’s nothing I like better than discovering a big chunk of dead code I can delete and not have to worry about understanding. Usually when I’m done with that I not only have a piece of code that I think is much better but I also can understand the original. That actually happened recently when I took Edi Weitz’s Hunchentoot web server and started stripping it down to create Toot (a basic web server) and Whistle (a more user friendly server built on top of Toot). In that case I also discarded the need for backward compatibility which allowed me to throw out lots of code. In that case I wasn’t going for a “better” piece of code so much as one that met my specific needs better.

If you had all the time in the world for a Lisp project, what would it be?

I should really get back to hacking on Toot and Whistle. I tried to structure things so that all the Hunchentoot functionality could be put back in a layer built on top of Toot—perhaps I should do that just to test whether my theory was right. On the other hand, I went down this path because the whole Hunchentoot API was too hard for me to understand. So maybe I should be getting Toot and Whistle stable and well-documented enough that someone else can take on the task of providing a Hunchentoot compatibility layer.

I’d also like to play around with my Go playing critters, reimplementing them in Lisp where I could take advantage of having a to-machine-code compiler available at run time.

PCL was the book, that opened the world of Lisp to me. I’ve also greatly enjoyed Coders at Work. So I’m looking forward for the next book you’d like to write. What would it be? :)

My current theory is that I’m going to write a book about statistics for programmers. Whenever I’ve tried to learn about statistics (which I’ve had to do, in earnest, for my new job) I find an impedance mismatch between the way I think and the way statisticians like to explain stuff. But I think if I was writing for programmers, then there are ways I could explain statistics that would be very clear to them at least. And I think there are lots of programmers who’d like to
understand statistics better and may have had difficulties similar to mine.

Discussion on Hacker News

submit