This example is a Conway's Game of Life implementation. 3 outputs are proposed (console, OCaml Graphics and HTML/JavaScript), each one using the same WebAssembly modules.
Console and Graphics implementations use external functions technique as the standard example. Here are the command lines to run in this directory to execute the programs:
- Console mode:
dune exec -- ./life_graphics.exe - Graphics mode:
dune exec -- ./life_console.exe
Several modules (defined in life.wat and life_loop.wat files) are linked.
Why are two .wat files required ?
Because, in JavaScript, the Sleep function uses the
Promise system
which cannot work in a wasm call context.
So, if we want to use the same WebAssembly components in all contexts,
the game loop had to be extracted in a separate module.
See the following section for JavaScript implementation details.
Here is a standard example of a wasm module called in a web page using the JavaScript API.
First of all, a compiled version of the WebAssembly module is needed, obtained by the
command line wat2wasm life.wat. wat2wasm is part of the
WABT: The WebAssembly Binary Toolkit.
As in OCaml in the previous contexts, external functions are defined in the environment execution
(here in JavaScript). As explained before, only one wasm module is imported (life.wasm) and
the game loop has been written directly in JavaScript.
This function (life()) must be async because sleep function is called in await mode.
To see the final result, simply open life.html in your favorite browser.
However, the command line dune exec -- ./runweb.exe launches a full build and open it
directly in your browser. Some additional dependencies are required including
ocaml-cohttp and
ocaml-crunch.