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diff --git a/talermerchantdemos/blog/articles/en/rms-lisp.html b/talermerchantdemos/blog/articles/en/rms-lisp.html new file mode 100644 index 0000000..a5f0dd1 --- /dev/null +++ b/talermerchantdemos/blog/articles/en/rms-lisp.html @@ -0,0 +1,592 @@ +<!--#include virtual="/server/header.html" --> +<!-- Parent-Version: 1.77 --> +<title>My Lisp Experiences and the Development of GNU Emacs +- GNU Project - Free Software Foundation</title> +<!--#include virtual="/gnu/po/rms-lisp.translist" --> +<!--#include virtual="/server/banner.html" --> +<h2>My Lisp Experiences and the Development of GNU Emacs</h2> + +<blockquote><p>(Transcript of Richard Stallman's Speech, 28 Oct 2002, at the +International Lisp Conference).</p></blockquote> + +<p>Since none of my usual speeches have anything to do with Lisp, none +of them were appropriate for today. So I'm going to have to wing it. +Since I've done enough things in my career connected with Lisp I +should be able to say something interesting.</p> + +<p>My first experience with Lisp was when I read the Lisp 1.5 manual +in high school. That's when I had my mind blown by the idea that there +could be a computer language like that. The first time I had a chance +to do anything with Lisp was when I was a freshman at Harvard and I +wrote a Lisp interpreter for the <abbr title="Programmed Data +Processor">PDP</abbr>-11. It was a very small machine +— it had something like 8k of memory — and I managed to write the +interpreter in a thousand instructions. This gave me some room for a +little bit of data. That was before I got to see what real software +was like, that did real system jobs.</p> + +<p>I began doing work on a real Lisp implementation with JonL White +once I started working at <abbr title="Massachusetts Institute of +Technology">MIT</abbr>. I got hired at the Artificial Intelligence Lab +not by JonL, but by Russ Noftsker, which was most ironic considering +what was to come — he must have really regretted that day.</p> + +<p>During the 1970s, before my life became politicized by horrible +events, I was just going along making one extension after another for +various programs, and most of them did not have anything to do with +Lisp. But, along the way, I wrote a text editor, Emacs. The +interesting idea about Emacs was that it had a programming language, +and the user's editing commands would be written in that interpreted +programming language, so that you could load new commands into your +editor while you were editing. You could edit the programs you were +using and then go on editing with them. So, we had a system that was +useful for things other than programming, and yet you could program it +while you were using it. I don't know if it was the first one of +those, but it certainly was the first editor like that.</p> + +<p>This spirit of building up gigantic, complicated programs to use in +your own editing, and then exchanging them with other people, fueled +the spirit of free-wheeling cooperation that we had at the AI Lab +then. The idea was that you could give a copy of any program you had +to someone who wanted a copy of it. We shared programs to whomever +wanted to use them, they were human knowledge. So even though there +was no organized political thought relating the way we shared software +to the design of Emacs, I'm convinced that there was a connection +between them, an unconscious connection perhaps. I think that it's the +nature of the way we lived at the AI Lab that led to Emacs and made it +what it was.</p> + +<p>The original Emacs did not have Lisp in it. The lower level +language, the non-interpreted language — was PDP-10 +Assembler. The interpreter we wrote in that actually wasn't written +for Emacs, it was written for <abbr title="Text Editor and +COrrector">TECO</abbr>. It was our text editor, and was an +extremely ugly programming language, as ugly as could possibly be. The +reason was that it wasn't designed to be a programming language, it +was designed to be an editor and command language. There were commands +like ‘5l’, meaning ‘move five lines’, or +‘i’ and then a string and then an ESC to insert that +string. You would type a string that was a series of commands, which +was called a command string. You would end it with ESC ESC, and it +would get executed.</p> + +<p>Well, people wanted to extend this language with programming +facilities, so they added some. For instance, one of the first was a +looping construct, which was < >. You would put those around +things and it would loop. There were other cryptic commands that could +be used to conditionally exit the loop. To make Emacs, we +<a href="#foot-1">(1)</a> added facilities to have subroutines with +names. Before that, it was sort of like Basic, and the subroutines +could only have single letters as their names. That was hard to +program big programs with, so we added code so they could have longer +names. Actually, there were some rather sophisticated facilities; I +think that Lisp got its unwind-protect facility +from TECO.</p> + +<p>We started putting in rather sophisticated facilities, all with the +ugliest syntax you could ever think of, and it worked — people were +able to write large programs in it anyway. The obvious lesson was that +a language like TECO, which wasn't designed to be a +programming language, was the wrong way to go. The language that you +build your extensions on shouldn't be thought of as a programming +language in afterthought; it should be designed as a programming +language. In fact, we discovered that the best programming language +for that purpose was Lisp.</p> + +<p>It was Bernie Greenberg, who discovered that it +was <a href="#foot-2">(2)</a>. He wrote a version of Emacs in Multics +MacLisp, and he wrote his commands in MacLisp in a straightforward +fashion. The editor itself was written entirely in Lisp. Multics Emacs +proved to be a great success — programming new editing commands +was so convenient that even the secretaries in his office started +learning how to use it. They used a manual someone had written which +showed how to extend Emacs, but didn't say it was a programming. So +the secretaries, who believed they couldn't do programming, weren't +scared off. They read the manual, discovered they could do useful +things and they learned to program.</p> + +<p>So Bernie saw that an application — a program that does something +useful for you — which has Lisp inside it and which you could extend +by rewriting the Lisp programs, is actually a very good way for people +to learn programming. It gives them a chance to write small programs +that are useful for them, which in most arenas you can't possibly +do. They can get encouragement for their own practical use — at the +stage where it's the hardest — where they don't believe they can +program, until they get to the point where they are programmers.</p> + +<p>At that point, people began to wonder how they could get something +like this on a platform where they didn't have full service Lisp +implementation. Multics MacLisp had a compiler as well as an +interpreter — it was a full-fledged Lisp system — but people wanted +to implement something like that on other systems where they had not +already written a Lisp compiler. Well, if you didn't have the Lisp +compiler you couldn't write the whole editor in Lisp — it would be +too slow, especially redisplay, if it had to run interpreted Lisp. So +we developed a hybrid technique. The idea was to write a Lisp +interpreter and the lower level parts of the editor together, so that +parts of the editor were built-in Lisp facilities. Those would be +whatever parts we felt we had to optimize. This was a technique that +we had already consciously practiced in the original Emacs, because +there were certain fairly high level features which we re-implemented +in machine language, making them into TECO +primitives. For instance, there was a TECO +primitive to fill a paragraph (actually, to do most of the work of +filling a paragraph, because some of the less time-consuming parts of +the job would be done at the higher level by a TECO +program). You could do the whole job by writing +a TECO program, but that was too slow, so we +optimized it by putting part of it in machine language. We used the +same idea here (in the hybrid technique), that most of the editor +would be written in Lisp, but certain parts of it that had to run +particularly fast would be written at a lower level.</p> + +<p>Therefore, when I wrote my second implementation of Emacs, I +followed the same kind of design. The low level language was not +machine language anymore, it was C. C was a good, efficient language +for portable programs to run in a Unix-like operating system. There +was a Lisp interpreter, but I implemented facilities for special +purpose editing jobs directly in C — manipulating editor buffers, +inserting leading text, reading and writing files, redisplaying the +buffer on the screen, managing editor windows.</p> + +<p>Now, this was not the first Emacs that was written in C and ran on +Unix. The first was written by James Gosling, and was referred to as +GosMacs. A strange thing happened with him. In the beginning, he +seemed to be influenced by the same spirit of sharing and cooperation +of the original Emacs. I first released the original Emacs to people +at MIT. Someone wanted to port it to run on Twenex — it +originally only ran on the Incompatible Timesharing System we used +at MIT. They ported it to Twenex, which meant that there +were a few hundred installations around the world that could +potentially use it. We started distributing it to them, with the rule +that “you had to send back all of your improvements” so we +could all benefit. No one ever tried to enforce that, but as far as I +know people did cooperate.</p> + +<p>Gosling did, at first, seem to participate in this spirit. He wrote +in a manual that he called the program Emacs hoping that others in the +community would improve it until it was worthy of that name. That's +the right approach to take towards a community — to ask them to join +in and make the program better. But after that he seemed to change the +spirit, and sold it to a company.</p> + +<p>At that time I was working on the GNU system (a free software +Unix-like operating system that many people erroneously call +“Linux”). There was no free software Emacs editor that ran +on Unix. I did, however, have a friend who had participated in +developing Gosling's Emacs. Gosling had given him, by email, permission +to distribute his own version. He proposed to me that I use that +version. Then I discovered that Gosling's Emacs did not have a real +Lisp. It had a programming language that was known as +‘mocklisp’, which looks syntactically like Lisp, but didn't +have the data structures of Lisp. So programs were not data, and vital +elements of Lisp were missing. Its data structures were strings, +numbers and a few other specialized things.</p> + +<p>I concluded I couldn't use it and had to replace it all, the first +step of which was to write an actual Lisp interpreter. I gradually +adapted every part of the editor based on real Lisp data structures, +rather than ad hoc data structures, making the data structures of the +internals of the editor exposable and manipulable by the user's Lisp +programs.</p> + +<p>The one exception was redisplay. For a long time, redisplay was +sort of an alternate world. The editor would enter the world of +redisplay and things would go on with very special data structures +that were not safe for garbage collection, not safe for interruption, +and you couldn't run any Lisp programs during that. We've changed that +since — it's now possible to run Lisp code during redisplay. It's +quite a convenient thing.</p> + +<p>This second Emacs program was ‘free software’ in the +modern sense of the term — it was part of an explicit political +campaign to make software free. The essence of this campaign was that +everybody should be free to do the things we did in the old days +at MIT, working together on software and working with +whomever wanted to work with us. That is the basis for the free +software movement — the experience I had, the life that I've lived at +the MIT AI lab — to be working on human knowledge, and +not be standing in the way of anybody's further using and further +disseminating human knowledge.</p> + +<p>At the time, you could make a computer that was about the same price +range as other computers that weren't meant for Lisp, except that it +would run Lisp much faster than they would, and with full type checking +in every operation as well. Ordinary computers typically forced you to +choose between execution speed and good typechecking. So yes, you could +have a Lisp compiler and run your programs fast, but when they tried to +take <code>car</code> of a number, it got nonsensical results and eventually +crashed at some point.</p> + +<p>The Lisp machine was able to execute instructions about as fast as +those other machines, but each instruction — a <code>car</code> instruction would +do data typechecking — so when you tried to get the <code>car</code> of a number +in a compiled program, it would give you an immediate error. We built +the machine and had a Lisp operating system for it. It was written +almost entirely in Lisp, the only exceptions being parts written in +the microcode. People became interested in manufacturing them, which +meant they should start a company.</p> + +<p>There were two different ideas about what this company should be +like. Greenblatt wanted to start what he called a +“hacker” company. This meant it would be a company run by +hackers and would operate in a way conducive to hackers. Another goal +was to maintain the AI Lab culture <a href="#foot-3">(3)</a>. +Unfortunately, Greenblatt didn't have any business experience, so +other people in the Lisp machine group said they doubted whether he +could succeed. They thought that his plan to avoid outside investment +wouldn't work.</p> + +<p>Why did he want to avoid outside investment? Because when a company +has outside investors, they take control and they don't let you have +any scruples. And eventually, if you have any scruples, they also +replace you as the manager.</p> + +<p>So Greenblatt had the idea that he would find a customer who would +pay in advance to buy the parts. They would build machines and deliver +them; with profits from those parts, they would then be able to buy +parts for a few more machines, sell those and then buy parts for a +larger number of machines, and so on. The other people in the group +thought that this couldn't possibly work.</p> + +<p>Greenblatt then recruited Russell Noftsker, the man who had hired +me, who had subsequently left the AI Lab and created a successful +company. Russell was believed to have an aptitude for business. He +demonstrated this aptitude for business by saying to the other people +in the group, “Let's ditch Greenblatt, forget his ideas, and +we'll make another company.” Stabbing in the back, clearly a +real businessman. Those people decided they would form a company +called Symbolics. They would get outside investment, not have +scruples, and do everything possible to win.</p> + +<p>But Greenblatt didn't give up. He and the few people loyal to him +decided to start Lisp Machines Inc. anyway and go ahead with their +plans. And what do you know, they succeeded! They got the first +customer and were paid in advance. They built machines and sold them, +and built more machines and more machines. They actually succeeded +even though they didn't have the help of most of the people in the +group. Symbolics also got off to a successful start, so you had two +competing Lisp machine companies. When Symbolics saw that LMI was not +going to fall flat on its face, they started looking for ways to +destroy it.</p> + +<p>Thus, the abandonment of our lab was followed by “war” +in our lab. The abandonment happened when Symbolics hired away all +the hackers, except me and the few who worked at LMI part-time. Then +they invoked a rule and eliminated people who worked part-time +for MIT, so they had to leave entirely, which left only +me. The AI lab was now helpless. And MIT had made a very +foolish arrangement with these two companies. It was a three-way +contract where both companies licensed the use of Lisp machine system +sources. These companies were required to let MIT use +their changes. But it didn't say in the contract that MIT +was entitled to put them into the MIT Lisp machine +systems that both companies had licensed. Nobody had envisioned that +the AI lab's hacker group would be wiped out, but it was.</p> + +<p> So Symbolics came up with a plan <a href="#foot-4">(4)</a>. They +said to the lab, “We will continue making our changes to the +system available for you to use, but you can't put it into +the MIT Lisp machine system. Instead, we'll give you +access to Symbolics' Lisp machine system, and you can run it, but +that's all you can do.”</p> + +<p>This, in effect, meant that they demanded that we had to choose a +side, and use either the MIT version of the system or the +Symbolics version. Whichever choice we made determined which system +our improvements went to. If we worked on and improved the Symbolics +version, we would be supporting Symbolics alone. If we used and +improved the MIT version of the system, we would be doing +work available to both companies, but Symbolics saw that we would be +supporting LMI because we would be helping them continue to exist. So +we were not allowed to be neutral anymore.</p> + +<p>Up until that point, I hadn't taken the side of either company, +although it made me miserable to see what had happened to our +community and the software. But now, Symbolics had forced the issue. +So, in an effort to help keep Lisp Machines +Inc. going <a href="#foot-5">(5)</a> — I began duplicating all +of the improvements Symbolics had made to the Lisp machine system. I +wrote the equivalent improvements again myself (i.e., the code was my +own).</p> + +<p>After a while <a href="#foot-6">(6)</a>, I came to the conclusion +that it would be best if I didn't even look at their code. When they +made a beta announcement that gave the release notes, I would see what +the features were and then implement them. By the time they had a real +release, I did too.</p> + +<p>In this way, for two years, I prevented them from wiping out Lisp +Machines Incorporated, and the two companies went on. But, I didn't +want to spend years and years punishing someone, just thwarting an +evil deed. I figured they had been punished pretty thoroughly because +they were stuck with competition that was not leaving or going to +disappear <a href="#foot-7">(7)</a>. Meanwhile, it was time to start +building a new community to replace the one that their actions and +others had wiped out.</p> + +<p>The Lisp community in the 70s was not limited to +the MIT AI Lab, and the hackers were not all +at MIT. The war that Symbolics started was what wiped +out MIT, but there were other events going on then. There +were people giving up on cooperation, and together this wiped out the +community and there wasn't much left.</p> + +<p>Once I stopped punishing Symbolics, I had to figure out what to do +next. I had to make a free operating system, that was clear — the +only way that people could work together and share was with a free +operating system.</p> + +<p>At first, I thought of making a Lisp-based system, but I realized +that wouldn't be a good idea technically. To have something like the +Lisp machine system, you needed special purpose microcode. That's what +made it possible to run programs as fast as other computers would run +their programs and still get the benefit of typechecking. Without +that, you would be reduced to something like the Lisp compilers for +other machines. The programs would be faster, but unstable. Now that's +okay if you're running one program on a timesharing system — if one +program crashes, that's not a disaster, that's something your program +occasionally does. But that didn't make it good for writing the +operating system in, so I rejected the idea of making a system like +the Lisp machine.</p> + +<p>I decided instead to make a Unix-like operating system that would +have Lisp implementations to run as user programs. The kernel wouldn't +be written in Lisp, but we'd have Lisp. So the development of that +operating system, the GNU operating system, is what led me to write +the GNU Emacs. In doing this, I aimed to make the absolute minimal +possible Lisp implementation. The size of the programs was a +tremendous concern.</p> + +<p>There were people in those days, in 1985, who had one-megabyte +machines without virtual memory. They wanted to be able to use GNU +Emacs. This meant I had to keep the program as small as possible.</p> + +<p>For instance, at the time the only looping construct was +‘while’, which was extremely simple. There was no way to +break out of the ‘while’ statement, you just had to do a +catch and a throw, or test a variable that ran the loop. That shows +how far I was pushing to keep things small. We didn't have +‘caar’ and ‘cadr’ and so on; “squeeze +out everything possible” was the spirit of GNU Emacs, the spirit +of Emacs Lisp, from the beginning.</p> + +<p>Obviously, machines are bigger now, and we don't do it that way +any more. We put in ‘caar’ and ‘cadr’ and so +on, and we might put in another looping construct one of these +days. We're willing to extend it some now, but we don't want to extend +it to the level of common Lisp. I implemented Common Lisp once on the +Lisp machine, and I'm not all that happy with it. One thing I don't +like terribly much is keyword arguments <a href="#foot-8">(8)</a>. +They don't seem quite Lispy +to me; I'll do it sometimes but I minimize the times when I do +that.</p> + +<p>That was not the end of the GNU projects involved with Lisp. Later +on around 1995, we were looking into starting a graphical desktop +project. It was clear that for the programs on the desktop, we wanted +a programming language to write a lot of it in to make it easily +extensible, like the editor. The question was what it should be.</p> + +<p>At the time, <abbr title="Tool Command Language">TCL</abbr> +was being pushed heavily for this purpose. I had a very low opinion +of TCL, basically because it wasn't Lisp. It looks +a tiny bit like Lisp, but semantically it isn't, and it's not as +clean. Then someone showed me an ad where Sun was trying to hire +somebody to work on TCL to make it the +“de-facto standard extension language” of the world. And I +thought, “We've got to stop that from happening.” So we +started to make Scheme the standard extensibility language for +GNU. Not Common Lisp, because it was too large. The idea was that we +would have a Scheme interpreter designed to be linked into +applications in the same way TCL was linked into +applications. We would then recommend that as the preferred +extensibility package for all GNU programs.</p> + +<p>There's an interesting benefit you can get from using such a +powerful language as a version of Lisp as your primary extensibility +language. You can implement other languages by translating them into +your primary language. If your primary language +is TCL, you can't very easily implement Lisp by +translating it into TCL. But if your primary +language is Lisp, it's not that hard to implement other things by +translating them. Our idea was that if each extensible application +supported Scheme, you could write an implementation +of TCL or Python or Perl in Scheme that translates +that program into Scheme. Then you could load that into any +application and customize it in your favorite language and it would +work with other customizations as well.</p> + +<p>As long as the extensibility languages are weak, the users have to +use only the language you provided them. Which means that people who +love any given language have to compete for the choice of the +developers of applications — saying “Please, application +developer, put my language into your application, not his +language.” Then the users get no choices at all — whichever +application they're using comes with one language and they're stuck +with [that language]. But when you have a powerful language that can +implement others by translating into it, then you give the user a +choice of language and we don't have to have a language war +anymore. That's what we're hoping ‘Guile’, our scheme +interpreter, will do. We had a person working last summer finishing up +a translator from Python to Scheme. I don't know if it's entirely +finished yet, but for anyone interested in this project, please get in +touch. So that's the plan we have for the future.</p> + +<p>I haven't been speaking about free software, but let me briefly +tell you a little bit about what that means. Free software does not +refer to price; it doesn't mean that you get it for free. (You may +have paid for a copy, or gotten a copy gratis.) It means that you have +freedom as a user. The crucial thing is that you are free to run the +program, free to study what it does, free to change it to suit your +needs, free to redistribute the copies of others and free to publish +improved, extended versions. This is what free software means. If you +are using a non-free program, you have lost crucial freedom, so don't +ever do that.</p> + +<p>The purpose of the GNU project is to make it easier for people to +reject freedom-trampling, user-dominating, non-free software by +providing free software to replace it. For those who don't have the +moral courage to reject the non-free software, when that means some +practical inconvenience, what we try to do is give a free alternative +so that you can move to freedom with less of a mess and less of a +sacrifice in practical terms. The less sacrifice the better. We want +to make it easier for you to live in freedom, to cooperate.</p> + +<p>This is a matter of the freedom to cooperate. We're used to +thinking of freedom and cooperation with society as if they are +opposites. But here they're on the same side. With free software you +are free to cooperate with other people as well as free to help +yourself. With non-free software, somebody is dominating you and +keeping people divided. You're not allowed to share with them, you're +not free to cooperate or help society, anymore than you're free to +help yourself. Divided and helpless is the state of users using +non-free software.</p> + +<p>We've produced a tremendous range of free software. We've done what +people said we could never do; we have two operating systems of free +software. We have many applications and we obviously have a lot +farther to go. So we need your help. I would like to ask you to +volunteer for the GNU project; help us develop free software for more +jobs. Take a look at <a href="/help/">http://www.gnu.org/help</a> to +find suggestions for how to help. If you want to order things, there's +a link to that from the home page. If you want to read about +philosophical issues, look in /philosophy. If you're looking for free +software to use, look in /directory, which lists about 1900 packages +now (which is a fraction of all the free software out there). Please +write more and contribute to us. My book of essays, “Free +Software and Free Society”, is on sale and can be purchased at +<a href="http://www.gnu.org/">www.gnu.org</a>. Happy hacking!</p> + +<ol> +<li id="foot-1">Guy Steele designed the original symmetrical Emacs +command set; then he and I began implementing Emacs (on top of TECO), +but after one long joint development session, Steele began drifting +away, so I finished Emacs. Others particularly including Eugene +C. Cicciarelli and Mike McMahon contributed substantially later +on.</li> + +<li id="foot-2">Bernie Greenberg says that Dan Weinreb's +implementation of Emacs for the Lisp Machine came before Greenberg's +implementation for Multics. I apologize for the mistake.</li> + +<li id="foot-3">Greenblatt's plan, as I understood it, was to hire lab +people part time, so that they could continue working at the AI Lab. +Symbolics hired them full time instead, so they stopped working at +MIT.</li> + +<li id="foot-4">The background of this plan, which I did not state +explicitly in the talk, is that during an initial period the ex-AI-Lab +hackers, whether at Symbolics or LMI, continued contributing their +changes to the MIT Lisp Machine system — even though the +contract did not require this. Symbolics' plan was to rupture this +cooperation unilaterally.</li> + +<li id="foot-5">It was not that I cared particularly about the fate of +LMI, but rather I did not want to let Symbolics gain through its +aggression against the AI Lab.</li> + +<li id="foot-6">This statement has been misconstrued as saying that I +never, ever looked at Symbolics' code. Actually it says I did look, +at first. The Symbolics source code was available at MIT, where I was +entitled to read it, and at first that's how I found out about their +changes. + +<p>But that meant I had to make a special effort to solve each problem +differently, in order to avoid copying Symbolics code. After a while, +I concluded it was better not to even look. That way I could write +code in whatever way was best, without concern for what might be in +Symbolics' code.</p></li> + +<li id="foot-7">Symbolics at one point protested to MIT that my work, +by thwarting their plan, had cost Symbolics a million dollars.</li> + +<li id="foot-8">I don't mind if a very complex and heavyweight +function takes keyword arguments. What bothers me is making simple +basic functions such as “member” use them.</li> +</ol> + +</div><!-- for id="content", starts in the include above --> +<!--#include virtual="/server/footer.html" --> +<div id="footer"> +<div class="unprintable"> + +<p>Please send general FSF & GNU inquiries to +<a href="mailto:gnu@gnu.org"><gnu@gnu.org></a>. +There are also <a href="/contact/">other ways to contact</a> +the FSF. Broken links and other corrections or suggestions can be sent +to <a href="mailto:webmasters@gnu.org"><webmasters@gnu.org></a>.</p> + +<p><!-- TRANSLATORS: Ignore the original text in this paragraph, + replace it with the translation of these two: + + We work hard and do our best to provide accurate, good quality + translations. 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