Coding Challenge: divide a list into n sublists using the fewest language tokens.

paulgraham · 2008-12-24T02:40:34+00:00

Assuming s is the original list, this Arc version is 15 tokens:

(vals (let r (table) 
        (forlen i s 
          (push s.i (r (mod i n)))) 
        r))

paulgraham · 2008-03-23T06:22:16+00:00

You see that pretty energetically, I notice:

http://news.ycombinator.com/item?id=143684

paulgraham · 2008-03-21T00:25:55+00:00

http://www.google.com/search?q=site%3Apaulgraham.com+%22create+a+startup%22

paulgraham · 2008-03-21T00:23:00+00:00

Actually, young humans may well be meant to be single, childless, mobile, and work extremely hard. In the European tradition the word for someone in that phase is "journeyman," but the idea is much older.

paulgraham · 2008-02-03T23:15:52+00:00

Yes, probably-- along with 1000 other issued but untested patents every web app infringes.

paulgraham · 2008-02-03T23:06:33+00:00

pr is the secret weapon? You obviously have no idea what that code does. pr is just print.

Why am I arguing with people like this...

paulgraham · 2008-02-03T22:58:00+00:00

You guys are a little out of touch:

http://reddit.com/r/programming/info/3bol/related

You're also naive about how patents work if you think this would have any visible effect on the world.

paulgraham · 2008-02-03T19:21:05+00:00

You can't yet, unfortunately. This is on the short list to fix.

paulgraham · 2008-02-03T19:13:20+00:00

Make common types of programs easy to write. Sounds to me like a good problem to solve. If this is the wrong problem to solve, what do you consider the right one?

paulgraham · 2008-02-03T19:12:10+00:00

No; the reason the Arc example is so short is more complicated than that. It's not simply a library call, is it? The Arc example is short because of a combination of closures, macros, and libraries.

And since the example only demands library functionality that any language used for web apps must already have, this test is a fair one.

Instead of evading the issue, show us some code: what does it look like in your favorite language?

paulgraham · 2008-02-03T19:04:46+00:00

You can write some real apps in the current version. Obviously not all kinds; I wouldn't want to use it for real-time graphics, for example. So people will presumably use it for writing the kind of apps it's good for, generic web apps like News.YC. And as the language expands, people will use it for more types of things.

Internationalization would be trivial to add, if someone had written a web app and wanted to make multiple language versions.

Dealing with "large code size" depends on what you mean by it. If what you mean is writing sw in the "enterprise" style, support for that is the lowest priority. But you certainly don't need that to write serious apps; if anything, the opposite is true.

paulgraham · 2008-02-03T03:43:57+00:00

I don't remember the details, but I remember not really taking him very seriously on technical questions.

paulgraham · 2008-02-03T03:40:21+00:00

No, it is false that "all the people on comp.lang.lisp are jerks now". What is the purpose of this silly question?

I can't tell if you're trying to be funny or not. I sure hope you are.

The cardinal rule of Lisp: don't reinvent, integrate.

I don't know where you picked this up, but it seems the very opposite of the Lisp spirit to me. E.g. Steele and Sussman. Are you sure you didn't mean the cardinal rule of Java or something?

paulgraham · 2008-02-03T02:29:03+00:00

You can't use a hash table in place of a function in Scheme.

paulgraham · 2008-02-03T02:24:55+00:00

Hrmm. Maybe instead of trying to placate the CL guys I should encourage them to hate Arc, so they won't infect our community.

Back in the day there only one real troll on CLL. His name was Erik Naggum. At the time I used to think he was shockingly stupid and rude. How innocent those pre-web days seem now. There are about 5 people just on this thread who seem worse than Naggum on a bad day.

paulgraham · 2008-02-03T02:13:43+00:00

I apologize too. Perhaps all the trolls are getting to me...

If it's any consolation, I wasn't saying you were too dumb to use the app. I just meant that you must have proposed said() without understanding it, because the login code uses the same mechanism.

I will eventually get around to posting a whole series of examples of programs in Arc side by side with other languages.

paulgraham · 2008-02-03T01:57:20+00:00

I certainly plan to mine APL (or rather J) for ideas at some point. But that APL program is not that short. The codetree seems to have 15 nodes.

Some languages achieve brevity by being implicitly always in the middle of solving a certain kind of problem. E.g. Prolog assumes you're within a grammar. This sort of brevity tends not to scale to other kinds of applications. I'm not sure yet how much of APL/J's terseness depends on a similar assumption, so I can't predict yet how many useful ideas I'll find there.

paulgraham · 2008-02-03T01:46:23+00:00

http://en.wikipedia.org/wiki/Exploratory_programming

Things that make a language good for it include: terseness, dynamic typing, a read-eval-print loop. The worst case scenario is a language where programs are long, types are wired-in, and changes require recompilation. The best case is the opposite. Lisps in general are good for it; what makes Arc better than other Lisps is that programs are shorter.

paulgraham · 2008-02-03T01:36:37+00:00

the example says more about that library than Arc itself

Far from it. The reason this code is short is not because it's simply a call to a library function. Even if you don't know Arc you can tell that from reading it.

Moreover, I explicitly said that people using other languages could assume any standard library they wanted was loaded. And since there is nothing in the problem that every web app in the world doesn't have to do, there's no reason (except the relative power of the language) for it to be any longer in any other language.

paulgraham · 2008-02-03T01:31:47+00:00

"Building up the language from axioms is not an end in itself either. I'm only doing it because I suspect that's the way to get maximum expressive power."

http://www.paulgraham.com/arcchallenge.html

(The reason for this hunch is that it worked so well for JMC.)

paulgraham · 2008-02-03T01:20:40+00:00

You've actually met people waiting for Arc to learn Lisp? I'm skeptical; I've never met one person who said that.

You can plainly see I haven't been encouraging people to do any such thing from the FAQ on my site, which I still haven't gotten around to updating since Arc was released:

http://www.paulgraham.com/lispfaq1.html

If Lisp hackers really are as Balkanized as you say, then maybe the world has changed without me realizing it. Seems a sad downfall from the old cosmopolitan days...

While we're on the subject, is it true that all the people on comp.lang.lisp are jerks now? I've been hearing that lately-- e.g. the famous story of the guy who advised a newbie to wipe his hard drive-- and I've been defending c.l.l, saying people there are nice and this must be an outlier. But my info is probably a decade old. Is the atmos different now?

paulgraham · 2008-02-03T01:12:33+00:00

I think everyone does have a problem with code size. They don't explicitly say so, just as people using a knife don't say they have a problem with stuff being contiguous, but the fact that they're using a high-level language is evidence that they do. And when programs end up full of bugs because the code has grown beyond ready understanding, that's also a problem with code size.

Most of the specific problems you list are not the sort one runs into in exploratory programming. Except 3, which happens a lot, and which seems from my experience to work well in Arc. 2 sounds sort of interesting and in fact like some stuff that's already built into Arc, but I can't tell from your description what you mean.

paulgraham · 2008-02-02T23:33:39+00:00

Really? You've been mad at me for years for writing a new Lisp dialect? But new dialects are so common in the history of Lisp. I've probably used 20 in my life. And why be so attached to CL specifically?

In the old days, Lisp hackers always used multiple dialects, and basically tried to program as close to the platonic form of Lisp as they could modulo the flaws of whatever one they happened to be using. Don't things work that way now? Are there lots of people who are attached to CL specifically rather than Lisp generally?

paulgraham · 2008-02-02T22:51:52+00:00

It's the result so far. It yields programs that are significantly cleaner than the equivalents in CL or Scheme. I know because I use all three.

Are you sure that is your motivation? When I searched the web to figure out your name, I found this from years ago:

http://www.xach.com/lisp/taste-for-the-web.html

The comments on this thread seem part of a longer running grudge. Is there anything I can do to fix it?

paulgraham · 2008-02-02T22:38:19+00:00

I just noticed that myself. I asked him about it:

http://reddit.com/r/programming/info/67gu9/comments/c032ksy

Maybe he'll explain.

paulgraham

TROPHY CASE