Re: Lua to ECMAscript static compiler (or translator)

[Philippe Lhoste <PhiLho@...>]

On 06/11/2011 16:03, Joshua Ballanco wrote:
> Have you looked at Emscripten (https://github.com/kripken/emscripten/wiki)? There's an
> example of Lua running in the browser here: http://syntensity.com/static/lua.html

If I understood correctly each project (from their description), lua2js (official name?) 
translates Lua code to JS code (a bit like what Xtend compiler does to Java, or lot of 
compilers in general do, using often C as target language), while Emscripten translated 
the C code of the Lua VM to JavaScript, interpreting Lua on the fly (would be like 
rewriting another JVM, to continue the analogy).

So, if I am not mistaken, Emscripten is able to run Lua code typed in the browser without 
assistance from a server, while lua2js would need to send the script to a server with a 
Python module to translate the code and send it back to the browser. Right?
Both approaches are interesting. As I believe the Emscripten was generated (by LLVM?), it 
should have a complete support of Lua features, but need to run a heavy machinery, not 
necessarily optimized for its target language (C idioms/pattern/tricks used in the Lua 
code might not be optimal for JS) to run the scripts, while lua2js probably generate a 
lighter JS and this code can be heavily optimized by the browser's engine.

Two interesting approaches.

I recall a failed attempt, some years ago, to make Lua to run natively (or with a plugin) 
in browsers, but the modern approach of using JS as the assembly language of browsers is 
probably saner, now that we have HTML5 (canvas and other facilities).

By saner, I don't mean it is a good idea, just that we don't have a choice (no standard 
bytecode here), if we want high compatibility, and well, it becomes usage, given the 
recent progress in JS engine speed.

--
Philippe Lhoste
--  (near) Paris -- France
--  http://Phi.Lho.free.fr
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