Re: [Haskell-cafe] ghci & ghc -> JS (Emscripten)

Thank you for your response :) Could you please answer one additional question - why you, while creating GHCJS didn't base on emscripten? Why haven't you patched it and created custom solution? Is GHCJS "production ready"? Also - Can I use GHCJS to compile big projects (like GHC or GHCI) to Javascript? When you mentioned the file sizes I thought it would be good to further introduce what we are trying to do. We want to be able to send a haskell code to a server to compile it and return the resulted JS to user as a compiled library. We want users to be able to connect these compiled functions together to get some interactive results. for example: user is creating 2 functions (pseudocode): a(x) and b(x). They are send to server and compiled to JS. Then in an online tool user is connecting (visually with lines) a data (lets say a list of ints) [] -> a -> b. While connecting it we want this tool to "interpret" such connections and visualise the data on each step - so we want to have some kind of "runtime" or "interpreter" on client side. 2013/7/3 Luite Stegeman

On Wed, Jul 3, 2013 at 11:06 AM, B B wrote:

...

Emscripten is meant to translate ANY LLVM IR code to javascript and it should work (as I belive).

It cannot compile ANY LLVM code: It's heavily geared towards porting C and C++ code to JavaScript, and still there are some limitatons, see:

https://github.com/kripken/emscripten/wiki/CodeGuidelinesAndLimitations

Also the FAQ mentions how event loops should be converted to something that emscripten can deal with:

https://github.com/kripken/emscripten/wiki/FAQ

Since the GHC runtime never returns, you'd probably have to do something similar.

I've tried to compile 'hello wrold' Haskell program to JS using Emscripten

...

but I faced a problem, that in generated LLVM IR code there is no C-like main function (https://github.com/kripken/emscripten/issues/500) so there has to be a runtime library that has to be linked and will run the code - is this "RTS" or something else? If its RTS I understeand I should compile it to javascript and then provide it as a library to emscripten? Do you have a working RTS js version?

I don't have a working version. The files you need are probably mostly in the rts directory of the GHC repository: https://github.com/ghc/ghc/tree/master/rts , but you might need a bit more, like libffi and gmp (unless you use integer-simple).

...

I want to simply try emscripten and see how it performs on such GHC generater LLVM IRs.

I don't think it's that easy... I'd expect a few weeks of work minimum to get very simple examples like "Hello, world" working. And a few months for something big like GHC.

Also keep in mind that the code will probably be pretty big, GHC (and GHCi, which is the same file) is ~65MB on my linux system, so getting well over 100MB of JavaScript wouldn't be terribly surprising.

luite