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

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.}

Agnostic

Why? [maybe there is a reason why they are not maintained!] – Coarsen

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 GOTOs anyway ...) – Infelicitous

@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? – Assyrian

@Ira: By that argument there should be more car factories in the world than cars. – Disjunctive

@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? – Assyrian

@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. – Disjunctive

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. goo.gl/F8xbu – Agnostic

I want haskell syntax, haskell type enforcement and all this awesome stuff but i need to release javascript code. – Izaak

@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. – Come

Answer 1

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

Kiyokokiyoshi

Elm is another interesting project in this space elm-lang.org – Kaneshakang

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. – Patterson

Answer 2

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.

Apocope

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. – Rival

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 (goo.gl/cX4fN). YHC is dead (goo.gl/icNTo), so I wouldn't even consider to evaluate it. jshaskell is a project on Google Code (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. – Agnostic

Answer 3

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.

Cosmography

on ghcjs, see also: haskell.org/pipermail/haskell-cafe/2011-May/091897.html – Hotze

@sclv, do you get to try ghcjs? Is it already usable, or for now more of a prototype? – Agnostic

@avernet, I didn't go further than reading the readme-file, so I can't tell. – Cosmography

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). – Virg

Answer 4

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.

Oxysalt

do you know why it isn't more famous? it's hell of an idea. maybe performance? – Friday

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. – Oxysalt

Answer 5

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.

Radiothermy

Answer 6

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)

Calpe

I'm pretty sure Yesod is server side, not client side like JS. – Sphygmomanometer

Still Yesod maintainers know about an option to compile Haskell to Javascript and created their own rating for the tools. – Cotopaxi