Wasmtime 44.0.0

Installation

You can add a package reference with the .NET SDK:

$ dotnet add package wasmtime

Introduction

For this introduction, we'll be using a simple WebAssembly module that imports a hello function and exports a run function:

(module
 (func $hello (import "" "hello"))
 (func (export "run") (call $hello))
)

To use this module from .NET, create a new console project:

$ mkdir wasmintro
$ cd wasmintro
$ dotnet new console

Next, add a reference to the Wasmtime package:

$ dotnet add package wasmtime

Replace the contents of Program.cs with the following code:

using System;
using Wasmtime;

using var engine = new Engine();

using var module = Module.FromText(
 engine,
 "hello",
 "(module (func $hello (import \"\" \"hello\")) (func (export \"run\") (call $hello)))"
);

using var linker = new Linker(engine);
using var store = new Store(engine);

linker.Define(
 "",
 "hello",
 Function.FromCallback(store, () => Console.WriteLine("Hello from C#!"))
);

var instance = linker.Instantiate(store, module);
var run = instance.GetAction("run")!;
run();

An Engine is created and then a WebAssembly module is loaded from a string in WebAssembly text format.

A Linker defines a function called hello that simply prints a hello message.

The module is instantiated and the instance's run export is invoked.

To run the application, simply use dotnet:

$ dotnet run

This should print Hello from C#!.