JavaScript to Lua translator | Hacker News Reader

JavaScript to Lua translator

github.com

35 pointsluu13 comments

For reference, here's why JavaScript to Lua converters are really hard to make feature complete.

http://phrogz.net/lua/LearningLua_FromJS.html

http://stackoverflow.com/questions/1022560/subtle-difference...

Do you have specific examples? I went over both lists, and most differences were either syntax, or "Lua has complicated feature X, JS doesn't."

Off of the top of my head, with varying difficulty

* js has UTF-16 strings with the same semantics(compare-by-value, immutable, interned) as lua strings. you could store UTF-16 in normal lua strings, but then you'd need some way of marshalling them for C code that expects const char* values

* JS has a lot of type coercions when doing binary operations, etc. replicating that seems like a source of indirection

* Lua tables have no explicit length, or any way to preallocate, so it's not entirely obvious what Array(len) or a.length = newlen would do

Take a look what happens if you write something simple, like "a[5]=1": http://es5.github.io/#x15.4.5.1

Or "a > b": http://es5.github.io/#x11.8.5

This, in turn, causes all sorts of weird behavior nicely described at https://www.destroyallsoftware.com/talks/wat

Tessel has a Javascript to Lua compiler too, as their hardware runs Lua underneath https://github.com/tessel/colony-compiler

Is there any reason why they didn't just stick with Lua, or some abstraction over Lua like Moonscript (http://moonscript.org)? Why is there such a big desire to put Javascript in places where it's not needed?

Author here. Actually, I wanted to do exactly the reverse - ability to use tons of Node.js modules in Lua, while coding in Lua. Think of it :)

Just in case you haven't already heard of what the nice folks at Tessel are doing, this may be useful to you:

https://github.com/tessel/colony-compiler

Author here. Tessel uses modified eLua, I want to use Node modules in vanilla Lua, so naturally that approach was not viable to me.

This repository is Windows only, it uses \ as a path delimiter all over the place. Gives you weird error messages on Linux.

Consider using / instead: it is accepted on both Windows and UNIX.

Yep, *nix support is definitely part of the plan.

How about a reverse translator that lets me write more lua and less javascript?

There is Moonshine http://moonshinejs.org/ to run Lua in the browser. There are a few more too.

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