golem-v2-wasm3/docs/Cookbook.md

Wasm3 Cookbook

Rust WASI app

Create a new project:

$ cargo new --bin hello
$ cd hello
$ rustup target add wasm32-wasi

Build and run:

$ cargo build --release --target wasm32-wasi

$ wasm3 ./target/wasm32-wasi/release/hello.wasm
Hello, world!

AssemblyScript WASI app

Create hello.ts:

import "wasi"

import {Console} from "as-wasi"
Console.log('Hello World!\n');

Create package.json:

{
  "name": "hello",
  "version": "1.0.0",
  "description": "Hello world with AssemblyScript and as-wasi",
  "main": "hello.ts",
  "scripts": {
    "build": "asc hello.ts -b hello.wasm"
  },
  "devDependencies": {
    "assemblyscript": "^0.10.0",
    "as-wasi": "^0.1.1"
  }
}

Build and run:

$ npm install
$ npm run build

$ wasm3 hello.wasm
Hello World!

TinyGo WASI app

Create hello.go:

package main

import "fmt"

func main() {
    fmt.Printf("Hello, %s!\n", "world")
}

Build and run:

$ tinygo build -o hello.wasm -target wasi ./hello.go

$ wasm3 hello.wasm
Hello, world!

Zig WASI app

Create hello.zig:

const std = @import("std");

pub fn main() !void {
    const stdout = std.io.getStdOut().writer();
    try stdout.print("Hello, {s}!\n", .{"world"});
}

Build and run:

$ zig build-exe -O ReleaseSmall -target wasm32-wasi hello.zig

$ wasm3 hello.wasm
Hello, world!

Zig library

Create add.zig:

export fn add(a: i32, b: i32) i64 {
    return a + b;
}

Build and run:

$ zig build-lib add.zig -O ReleaseSmall -target wasm32-freestanding

$ wasm3 --repl add.wasm
wasm3> add 1 2
Result: 3

C/C++ WASI app

The easiest way to start is to use Wasienv.

Create hello.cpp:

#include <iostream>
int main() {
    std::cout << "Hello, world!" << std::endl;
    return 0;
}

Or hello.c:

#include <stdio.h>
int main() {
   printf("Hello, %s!\n", "world");
   return 0;
}

Build and run:

$ wasic++ -O3 hello.cpp -o hello.wasm
$ wasicc -O3 hello.c -o hello.wasm

$ wasm3 hello.wasm
Hello World!

Limitations:

• setjmp/longjmp and C++ exceptions are not available
• no support for threads and atomics
• no support for dynamic libraries