wasmslime/README.md

# wasmslime

.. is a library providing [Wasmtime] bindings for use with the [Zig] language. This is my first project I've tackled with Zig, as I wanted to play around with WebAssembly for sandboxing reasons, and the libraries I have found are both outdated and incomplete. Though they did provide some starting help.

Of course, this library too is likely very much incomplete, maybe even broken. I just wanted to share it as I'm quite proud and perhaps someone else finds some use in it. Feel free to yoink anything from `wasmslime` as you see fit.

## Example

```zig
const wat_bytes =
    \\(module
    \\  (func $hello (import "env" "print_hello"))
    \\  (func (export "main") (call $hello)))
;

fn print_hello() void {
    const stdout = @import("std").io.getStdOut().writer();
    stdout.print("Hello, Slime!\n", .{}) catch unreachable;
}

pub fn main() !void {
    const wasm = @import("wasmslime");
    // Should deinit Wasm objects. Omitted for brevity.
    var engine = try wasm.Engine.initDefault();
    var module = try wasm.Module.initFromWat(engine, wat_bytes, null);
    var linker = wasm.Linker.init(engine);
    try linker.defineFuncFromFn("env", "print_hello", print_hello, null);
    var store = wasm.Store.init(engine);
    var context = store.getContext();
    var instance = try linker.instantiate(context, module, null);
    const run_func = try instance.getFunc(context, "main");
    try run_func.call(context, .{}, void, null);
}
```

## Setup as Dependency

Currently requires [Wasmtime] to be installed as a system library. Unsure about the possibility of statically linking it instead, and the up- and downsides that come with that. I may look into this in the future.

`wasmslime` uses Zig version `0.11` and thus makes use of its new [Package Management] feature. Since this is a pretty new feature that currently isn't documented beyond what's shared in the release notes, I'll give a brief overview of how to add it as a dependency to your project.

### `build.zig.zon`

```zig
.{
    .name = "my_amazing_project",
    .version = "0.1.0",
    .dependencies = .{
        .wasmslime = .{
            .url = "https://git.mcft.net/copygirl/wasmslime/archive/main.tar.gz",
            .hash = "00000000000000000000000000000000000000000000000000000000000000000000",
        },
    },
}
```

Providing an invalid hash will make the build system complain about what it should actually be. Keep in mind the string needs to be the correct length, however. This way I don't have to update the README each commit.

Downloaded packages end up in `~/.cache/zig/`. If the hash already matches an existing package here, it will be used regardless of the source URL. If you run into issues, you could consider clearing Zig's cache folder.

### `build.zig`

```zig
...
const exe = b.addExecutable(...);

const wasmslime = b.dependency("wasmslime", .{ .target = target, .optimize = optimize });
exe.addModule("wasmslime", wasmslime.module("wasmslime"));
exe.linkLibrary(wasmslime.artifact("wasmslime"));

b.installArtifact(exe);
...
```

[Wasmtime]: https://wasmtime.dev/
[Zig]: https://ziglang.org/
[Package Management]: https://ziglang.org/download/0.11.0/release-notes.html#Package-Management