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Walt In 5 Minutes
Walt's ultimate goal is to make WebAssembly accessible to regular JavaScript programmers and to do so in a sane and simple fashion. There are only a few prerequisites and most of the necessary tools you most likely have already installed.
Here is a small step-by-step tutorial to get from an empty project directory to loading WebAssembly in about five minutes:
There are many different ways you could install these and manage the rapidly changing versions. I personally recommend installing n (https://github.com/tj/n) as a node version manager.
In a new empty folder create a simple folder structure for your new project
├── dist
└─┬ src
└── walt
npm init -y
This will create a new package.json file. npm will prefill it with the most useful default values.
npm install --save-dev webpack
While it is possible to create a Walt project without Webpack, this will make your life much easier. Walt comes with a Webpack loader that makes regular recompilation a breeze 🌬️
npm install --save-dev walt-compiler walt-loader
Create a new file in your project folder and save it as webpack.config.js
const path = require('path')
module.exports = {
resolve: {
extensions: [".walt"]
},
module: {
rules: [
{ test: /\.walt$/, use: 'walt-loader' }
]
},
entry: './src/index.js',
mode: 'production',
output: {
filename: 'bundle.js',
path: path.resolve(__dirname, 'dist')
}
}Create a new file in your project folder and save it as index.html
<html>
<head>
<title>Getting Started</title>
</head>
<body>
<script src="dist/bundle.js"></script>
</body>
</html>Create a new file in your project folder and save it as src/index.js
import makeCounter from './walt/counter.walt'
makeCounter().then(wasmModule => {
console.log(wasmModule.instance.exports.increment()) // 1
console.log(wasmModule.instance.exports.increment()) // 2
console.log(wasmModule.instance.exports.decrement()) // 1
})Create a new file in the src/walt folder of your project and save it as counter.walt
let counter: i32 = 0;
export function decrement(): i32 {
counter -= 1;
return counter;
}
export function increment(): i32 {
counter += 1;
return counter;
}
This would probably also be a good time to register .walt files in your OS to open with your favorite editor.
At this point you should have files in directories arranged like this
├── dist
├── node_modules
├─┬ src
│ ├─┬ walt
│ │ └── counter.walt
│ └── index.js
├── index.html
├── package-lock.json
├── package.json
└── webpack.config.js
Use Webpack to create the bundle.js file in the dist folder
npx webpack --config webpack.config.js
When you open index.html in a browser it will load the bundle.js and execute it. Open the JavaScript console and you should see
1
2
1
Congratulations! You just ran your first WebAssembly script!