ysugimoto/webassembly-lua

webassembly-lua

Write and compile as WebAssembly program by lua script.

Note: this project is still under development. We have to do more improvement

Requirements

• https://github.com/kripken/emscripten
• https://www.lua.org/ (prefer to use latest version)
• Python 3.6.5+

To avoid to polute your environment, we prefer to use prebuilt docker image on https://hub.docker.com/r/ysugimoto/webassembly-lua/.

How to use

Write lua script

Here is example Hello World script:

lua
function hello_world()
  return 'Hello, WebAssembly Lua!'
end

Make sure the function declares as global in order to access from C program. And, also you can spcify some function arguments like:

lua
function hell_something(something):
  return ('Hello, %s!'):format(something)
end

Then, you need to rememeber what type of argument should be supplied and what type of value will return (supports string or int for now).

Write definitions in definition.yml

The definition.yml is configuration for generate / compile WebAssembly ***ary. Format is following:

yaml
dependencies:
  - luaposix

functions:
  hello_something:
    return : string
    args:
      - string

entry_file: hello_world.lua

Describes each fields:

Compile as WebAssembly program

On docker image, the image has emcc-lua command:

shell
$ docker pull ysugimoto/webassembly-lua
$ docker run --rm -v $PWD:/src ysugimoto/webassembly-lua emcc-lua

The emcc-lua finds definition.yml in current working directory (in this case, $PWD) and start to build. If build successfully, you can see a hello_world.[html,js,wasm]in your directory. The output file is named byentry_file` in definition.yml.

Run WebAssembly program

Open created or write HTML to run compiled WebAssembly program like:

CODE_TOKEN_4

And run local server in your favorite way (e.g python -m http.server) and access to http://localhost:8000/hello_world.html (port may need), then you can see Hello, WebAssembly Lua! message in your browser console.

Features

• Compile single lua script to WebAssembly binary
• Support for return type of string and int
• Support to call function with any arguments
• Enable to bundle some libraries (e.g. hosted on luarocks, or Independent C libraries)

TODOs

• Support to require other lua modules which you defined as other file, installed via luarocks
• Support to apply function arguments as detected types
• Works with more complicated script. Now we can work on simple script.
• Support some structured return type which can use in JavaScript (Array, Object -- especially JSON --)
• Try to compile various libraries (Now we tried to bundle luaposix, it's fine to work)

Author

Yoshiaki Sugimoto

License

MIT