5 ms·

How Kal Compiles Itself

87 points by rzimmerman 13y ago

lmartel 13y ago
This is definitely one of the coolest "Show HN"-style projects I've seen in a while. Great work!
jashkenas 13y ago
As CoffeeScript also went through this same process, bootstrapping itself away from an original Ruby-based compiler (at this moment: https://github.com/jashkenas/coffee-script/commit/6446e0004c6e53cf909b300ebb12a934ccb33eb6 https://github.com/jashkenas/coffee-script/commit/6446e0004c...), Kal is now in some sense "two self-hosted steps" away from a "normal" language. That's pretty neat. GorillaScript (here: https://github.com/ckknight/gorillascript/tree/master/src https://github.com/ckknight/gorillascript/tree/master/src), Coco (here: https://github.com/gkz/LiveScript/tree/master/src https://github.com/gkz/LiveScript/tree/master/src) et al, are also implemented in themselves. I hope that this trend of compile-to-JS languages tending to self-host continues.
drivebyacct2 13y ago
My understanding is that many self hosting compilers do something similar to bootstrap, etc. Very cool to get an inside look despite my other feelings of Kal.
aa0 13y ago
While it may be cool that Kal compiles itself, unless there is a source tree for the Kal binaries themselves, there is a indubitably huge issue of trust with distributing binaries. Relevant: http://cm.bell-labs.com/who/ken/trust.html http://cm.bell-labs.com/who/ken/trust.html
- spicyj 13y ago
  The article links to that very page: > anarbi posted a great [link] about how compilers can contain a memory of things that are no longer in the code.
vorg 13y ago
I'm wondering what Kal's license is? I'm especially wondering if source written in the language itself qualifies as open source under the terms of any/some/most/all of the Free and Open Source licenses, or if the source of every version ever used to compile another version must be made available?
- fleitz 13y ago
  All self-hosted GPL compilers have this 'problem'... The output of the compiler under the GPL can be licensed however you like.
_random_ 13y ago
A word of warning: the name 'Kal' will be funny to russian-speaking devs. In case you care.
- teebrz 13y ago
  Sure, it would be a poor name for a new soda you plan to market in Russian-speaking countries; but probably not really worth mentioning here. I'm sure you realize, but lots of Russian words/phrases sound funny (or obscene) in English too - this is true of every language and vice versa. Naming things is hard enough already without trying to cover what it might sound like in every major language.
  - deleted 13y ago
    [deleted]
  - solomatov 13y ago
    Kal means feces in Russian. >Naming things is hard enough already without trying to cover what it might sound like in every major language. IMO, when you give a name to internationally used thing, this should be taken care of. I.e. name shouldn't sound funny obscene in any of the major languages.
    - teebrz 13y ago
      I think most Russian-speaking programmers are intelligent enough to understand it's a foreign name, especially since it's written as "kal" and not "кал". > I.e. name shouldn't sound funny obscene in any of the major languages. My point is that this is probably more difficult than you realize. It's also pointless; if you're the maker of a consumer product (like a soda) and you expect to market it in Russian-speaking countries, then of course you need to watch out for such things. Something like this which is only incidentally used by a small portion of technically literate Russian speakers - it's not really worth bothering with.
- rzimmerman 13y ago
  Yeah, that's kind of a shame. I'm not planning on changing it though. I figure most russian devs will have a sense of humor about it. I guess with a word that short, most languages are bound to have a meaning for it. I chose it because in Hebrew it means simple/easy/BASIC.
callesgg 13y ago
So in essense it dosen't, not more than any other language atleast. It originaly compiles from coffescript. It's a point of view thing.
- norswap 13y ago
  It does. Coffeescript is not involved at any point in the current compilation process. It did not originally however.
teleological 13y ago
"wait for" and "for parallel" seem useful. Are they inspired by constructs in other languages, or do they have analogs in other languages?
- rzimmerman 13y ago
  "wait for" turns out to be somewhat analogous to the upcoming "yield" statement in ECMAScript 6 as well as .NET patterns for async code. "for parallel" must exist somewhere (it almost looks like functional programming). I actually added it as an afterthought when I decided "wait for" ought to work inside of loops. It uses the same mechanism as async.js's "map".
- octo_t 13y ago
  Fortress and Scala have similar concepts (0 to 10).par.foreach(expensiveOp)
  - qu4z-2 13y ago
    C# has range.AsParallel().Select(expensiveOp); Which is hilariously verbose, and map is called select. But it's nice to have...
anaphor 13y ago
Why isn't anyone doing languages that compile to a trampolined form of JS? It would kill two birds with one stone: you get to write recursive code without wasting memory, and you can easily implement a lightweight thread scheduler. It seems like people are just picking the low hanging fruit, i.e. "JS syntax is ugly, let's implement a desugarer". I haven't seen many people try to change the semantics of JS much. maybe Whalesong or something, but nobody is using that.
- kevingadd 13y ago
  One reason is that performance would be miserable. Most current JS runtimes aren't very good at optimizing that kind of code, and it actually uses quite a bit of extra memory.

87 points by rzimmerman 13y ago

This is definitely one of the coolest "Show HN"-style projects I've seen in a while. Great work!

As CoffeeScript also went through this same process, bootstrapping itself away from an original Ruby-based compiler (at this moment: https://github.com/jashkenas/coffee-script/commit/6446e0004c6e53cf909b300ebb12a934ccb33eb6 https://github.com/jashkenas/coffee-script/commit/6446e0004c...), Kal is now in some sense "two self-hosted steps" away from a "normal" language. That's pretty neat. GorillaScript (here: https://github.com/ckknight/gorillascript/tree/master/src https://github.com/ckknight/gorillascript/tree/master/src), Coco (here: https://github.com/gkz/LiveScript/tree/master/src https://github.com/gkz/LiveScript/tree/master/src) et al, are also implemented in themselves. I hope that this trend of compile-to-JS languages tending to self-host continues.

drivebyacct2 13y ago

My understanding is that many self hosting compilers do something similar to bootstrap, etc. Very cool to get an inside look despite my other feelings of Kal.

aa0 13y ago

While it may be cool that Kal compiles itself, unless there is a source tree for the Kal binaries themselves, there is a indubitably huge issue of trust with distributing binaries. Relevant: http://cm.bell-labs.com/who/ken/trust.html http://cm.bell-labs.com/who/ken/trust.html

spicyj 13y ago
The article links to that very page: > anarbi posted a great [link] about how compilers can contain a memory of things that are no longer in the code.

vorg 13y ago

I'm wondering what Kal's license is? I'm especially wondering if source written in the language itself qualifies as open source under the terms of any/some/most/all of the Free and Open Source licenses, or if the source of every version ever used to compile another version must be made available?

fleitz 13y ago
All self-hosted GPL compilers have this 'problem'... The output of the compiler under the GPL can be licensed however you like.

_random_ 13y ago

A word of warning: the name 'Kal' will be funny to russian-speaking devs. In case you care.

teebrz 13y ago
Sure, it would be a poor name for a new soda you plan to market in Russian-speaking countries; but probably not really worth mentioning here. I'm sure you realize, but lots of Russian words/phrases sound funny (or obscene) in English too - this is true of every language and vice versa. Naming things is hard enough already without trying to cover what it might sound like in every major language.
- deleted 13y ago
  [deleted]
- solomatov 13y ago
  Kal means feces in Russian. >Naming things is hard enough already without trying to cover what it might sound like in every major language. IMO, when you give a name to internationally used thing, this should be taken care of. I.e. name shouldn't sound funny obscene in any of the major languages.
  - teebrz 13y ago
    I think most Russian-speaking programmers are intelligent enough to understand it's a foreign name, especially since it's written as "kal" and not "кал". > I.e. name shouldn't sound funny obscene in any of the major languages. My point is that this is probably more difficult than you realize. It's also pointless; if you're the maker of a consumer product (like a soda) and you expect to market it in Russian-speaking countries, then of course you need to watch out for such things. Something like this which is only incidentally used by a small portion of technically literate Russian speakers - it's not really worth bothering with.
rzimmerman 13y ago
Yeah, that's kind of a shame. I'm not planning on changing it though. I figure most russian devs will have a sense of humor about it. I guess with a word that short, most languages are bound to have a meaning for it. I chose it because in Hebrew it means simple/easy/BASIC.

callesgg 13y ago

So in essense it dosen't, not more than any other language atleast. It originaly compiles from coffescript. It's a point of view thing.

norswap 13y ago
It does. Coffeescript is not involved at any point in the current compilation process. It did not originally however.

teleological 13y ago

"wait for" and "for parallel" seem useful. Are they inspired by constructs in other languages, or do they have analogs in other languages?

rzimmerman 13y ago
"wait for" turns out to be somewhat analogous to the upcoming "yield" statement in ECMAScript 6 as well as .NET patterns for async code. "for parallel" must exist somewhere (it almost looks like functional programming). I actually added it as an afterthought when I decided "wait for" ought to work inside of loops. It uses the same mechanism as async.js's "map".
octo_t 13y ago
Fortress and Scala have similar concepts (0 to 10).par.foreach(expensiveOp)
- qu4z-2 13y ago
  C# has range.AsParallel().Select(expensiveOp); Which is hilariously verbose, and map is called select. But it's nice to have...

anaphor 13y ago

Why isn't anyone doing languages that compile to a trampolined form of JS? It would kill two birds with one stone: you get to write recursive code without wasting memory, and you can easily implement a lightweight thread scheduler. It seems like people are just picking the low hanging fruit, i.e. "JS syntax is ugly, let's implement a desugarer". I haven't seen many people try to change the semantics of JS much. maybe Whalesong or something, but nobody is using that.

kevingadd 13y ago
One reason is that performance would be miserable. Most current JS runtimes aren't very good at optimizing that kind of code, and it actually uses quite a bit of extra memory.