What is the most production-level Haskell to JavaScript compiler, to write code running in the browser?

Question

I am not looking for a necessarily super-robust solution with a 10-year track record, but for something that can be used in a real applications, and goes beyond just being able to run an Hello World example.

My preference is to run the compiler on the server, so I can compile Haskell code ahead of time. Of course, the solution would need to be more than just a compiler, and enable Haskell code to access the API available on the browser (DOM, XHR…).

_{Footnote: the projects I have seen so far don't seem to be actively maintained, or to go beyond being able to run "Hello world", or in some case even to go beyond a project description.}

Most existing Haskell implementations compile to C or x86. I'm pretty sure there's more deployed ECMAScript engines than either C or x86 engines. So, it makes perfect sense, doesn't it? ECMAScript is a pretty fine assembly language, too, except it desperately needs `GOTO`, continuations, a reified stack or something like that. (Note: I'm only talking of ECMAScript *as an assembly language*. Adding `GOTO` to ECMAScript *as a programming language* would be a terrible mistake. Continuations OTOH would be pretty cool. Well, actually ECMASCript already has exceptions which are `GOTO`s anyway ...) — Jörg W Mittag, Jun 08 '11 at 00:21
@Jorg: uh, aren't most JavaScript engines implemented in C? Implications: #(JavaScriptEngines)<=#(CEngines). And the number of x86 engines on the planet is pretty astonishing. Why target JavaScript with so many C and x86 engines lying around? — Ira Baxter, Jun 08 '11 at 01:53
@Ira: By that argument there should be more car factories in the world than cars. — hammar, Jun 08 '11 at 06:51
@hammar: while your argument is "cute", x86s are in pretty wide actual distribution (likely more of them than actual cars). C compilers may not actually have such wide distribution in practice, but given for any JavaScript implementation there was likely a C compiler [with a significant fraction of these likley being GCC], and such compilers in general are not hard to get, anybody contemplating a JavaScript target can surely acquire the corresponding C compiler without a lot of effort. So I just don't see the point. What does a Haskell programmer get out a JavaScript implementation? — Ira Baxter, Jun 08 '11 at 13:59
@Ira: It is almost certainly true that there are more C implementations than JavaScript ones, although this does not follow logically from the fact that most of them are written in C. Anyway, I guess compiling Haskell to JavaScript is mostly motivated by a desire to have access to the strong static guarantees of Haskell in the browser. — hammar, Jun 08 '11 at 14:13
After reading the first two comments, and having asked the question myself, I have to post a link to Steve Yegge's blog post "Haskell Researchers Announce Discovery of Industry Programmer Who Gives a Shit". Enjoy. http://goo.gl/F8xbu — avernet, Jun 15 '11 at 01:23
I want haskell syntax, haskell type enforcement and all this awesome stuff but i need to release javascript code. — lud, Jun 11 '13 at 21:56
@JörgWMittag What in the world are you talking about? There are far more x86 chips out there than EMCAscripting engines, and there are tons more C compilers than JS VIMs. A cursory google search would have verified this. Furthermore, exceptions are NOT goto's; they are far more powerful in general. — Alice, Mar 02 '15 at 01:29

score 21 · Accepted Answer · edited Feb 18 '15 at 15:00

21

There is a more complete list here:

http://www.haskell.org/haskellwiki/The_JavaScript_Problem

and there is also Fay (although it is only a subset of haskell)

https://github.com/faylang/fay

edited Feb 18 '15 at 15:00

Pandafox

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answered May 14 '12 at 12:51

David

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Elm is another interesting project in this space http://elm-lang.org/ – Ben Racine Jan 30 '13 at 17:57
And judging by the linked wiki page. JMacro seems like its most mature, but is just a EDSL within Haskell. Haste seems like the next most mature, and seems more faithful to haskell itself. I looked at its Github page, and it seems to be actively maintained. – Will Sewell May 07 '14 at 20:32

score 9 · Answer 2 · answered Dec 05 '12 at 18:49

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While GHCJS does not seem to be actively maintained, Emscripten seems to be quite current.

Emscripten compiles LLVM bitcode to JavaScript.
GHC's LLVM backend appears to be actively developed.
Intuitively, to answer the question, the following pipeline might not be very far from "production quality": Haskell lexemes (-> GHC ->) LLVM lexemes (-> Emscripten ->) JavaScript lexemes

I'll admit that this is a speculative post.

answered Dec 05 '12 at 18:49

jerng

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do you know why it isn't more famous? it's hell of an idea. maybe performance? – András Gyömrey Dec 19 '12 at 21:57
One guy seems to have got it working before. (Google for it.) Could not find any other information on that in the past. Maybe it's not in demand. I haven't had time to test it. Maybe soon. – jerng Dec 25 '12 at 17:12

score 9 · Answer 3 · answered Jun 07 '11 at 22:31

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You may find this List useful: https://github.com/jashkenas/coffee-script/wiki/List-of-languages-that-compile-to-JS

From the List:

* UHC (Utrecht Haskell Compiler) backend converts UHC core to JavaScript, allowing the compiling of Haskell code to JS.
* YHC (York Haskell Compiler) backend, as above but with YHC core language.
* jshaskell

I know its not Haskell but Coffee script is expression based and rather elegant IMHO.

answered Jun 07 '11 at 22:31

Adam Gent

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In this list «Emscripten LLVM to JavaScript compiler.» is under C/C++ section which is wrong as it can compile any language that can be compiled to LLVM bytecode, including [Haskell](http://hackage.haskell.org/trac/ghc/wiki/Commentary/Compiler/Backends/LLVM). – ZyX Jun 08 '11 at 11:18
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Out of those, UHC looks the most promising. As of today, its last release was in Oct 2010, and they have a blog with JavaScript specific posts (http://goo.gl/cX4fN). YHC is dead (http://goo.gl/icNTo), so I wouldn't even consider to evaluate it. jshaskell is a project on Google Code (http://goo.gl/d85K4). As of today, the repository hasn't been touched since Jul 2010, and Google Code describes the activity of the project as "None"; not very encouraging. – avernet Jun 09 '11 at 00:33

score 9 · Answer 4 · answered Jun 15 '11 at 19:43

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I have stumbled upon this project called ghcjs

It seems promising!

Quote from the README:

Haskell to Javascript translator

Project aims to provide solution to

compile modern Haskell libraries to Javascript files and use them in Ajax applications or

develop entire Ajax application in Haskell language

Previous version of project is located at vir.mskhug.ru.

answered Jun 15 '11 at 19:43

Rotsor

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on ghcjs, see also: http://www.haskell.org/pipermail/haskell-cafe/2011-May/091897.html – sclv Jun 15 '11 at 20:20
@sclv, do you get to try ghcjs? Is it already usable, or for now more of a prototype? – avernet Jun 15 '11 at 22:58
@avernet, I didn't go further than reading the readme-file, so I can't tell. – Rotsor Jun 16 '11 at 00:43
I can say that as of 2015 april, GHCJS seems highly approachable and quite mature; I was able to get to a running Hello World without a glitch, which I cannot say about Haste at this time (which is the only other "true", i.e. non-dialect Haskell->JS compiler). – Erik Kaplun Apr 21 '15 at 09:43

score 2 · Answer 5 · answered Jun 19 '12 at 02:16

This language, Roy, is perhaps not really Haskell (?), but it seems very similar:

http://roy.brianmckenna.org/

Roy seems to be alive; there are many forks in the GitHub repo: https://github.com/pufuwozu/roy
and it seems to be alive: https://github.com/pufuwozu/roy/graphs

If you're using Play Framework 2.0, then there's a plugin, Ray, to run Roy on Play Framework 2.0:

http://brianmckenna.org/blog/ray
https://github.com/pufuwozu/ray

The last commit was four months ago, which is rather long ago keeping in mind that Play Framework 2 was released perhaps 4 or 5 months ago.

Gerold Meisinger · Answer 6 · 2014-04-18T21:12:03.547

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There is a list of "most production level" candidates from Yesod: https://github.com/yesodweb/yesod/wiki/Javascript-Options (Yesod is a very popular Haskell webframework so they may know what they are talking about)

edited Apr 18 '14 at 21:12

answered May 23 '12 at 19:58

Gerold Meisinger

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I'm pretty sure Yesod is server side, not client side like JS. – jmite Aug 30 '13 at 02:38
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Still Yesod maintainers know about an option to compile Haskell to Javascript and created their own rating for the tools. – Anton Oct 15 '14 at 18:08

What is the most production-level Haskell to JavaScript compiler, to write code running in the browser?

6 Answers6

Haskell to Javascript translator

Linked