An experimental work-in-progress (WIP) WebAssembly runtime written in Gleam.

Nowadays, many languages ​​support Wasm as a target, from mainstream ones like C++ and Rust, as well as newer ones like Odin and Grain. The purpose of this project is to use WebAssembly to create an alternative interoperability layer to Erlang's virtual machine NIFs.

gleam add gwr

// fib.rs

#![no_std]

#[panic_handler]
pub fn panic(_info: &core::panic::PanicInfo) -> !
{
    loop {}
}

#[unsafe(no_mangle)]
pub extern fn fib(value: i32) -> i32
{
    match value
    {
        v if v <= 0 => 0,
        v if v <= 2 => 1,
        _ => fib(value - 1) + fib(value - 2)
    }
}

rustc --crate-type cdylib --target wasm32-unknown-unknown -C debuginfo=none -C panic=abort -C strip=symbols -C opt-level=3 ./fib.rs -o ./fib.wasm

Using the wat2wasm tool from wabt.

;; fib.wat

(module
    (func $fib (export "fib") (param $value i32) (result i32)
        local.get $value
        i32.const 0
        i32.le_s
        if
            i32.const 0
            return
        end
        local.get $value
        i32.const 2
        i32.le_s
        if
            i32.const 1
            return
        end
        local.get $value
        i32.const 1
        i32.sub
        call $fib
        local.get $value
        i32.const 2
        i32.sub
        call $fib
        i32.add
        return
    )
)

wat2wasm -o ./fib.wasm ./fib.wat

Using the simplifile package to read the module file.

gleam add simplifile

import gwr/gwr
import gwr/execution/runtime
import simplifile

pub fn main()
{
    let assert Ok(data) = simplifile.read_bits(from: "fib.wasm")
    let assert Ok(binary) = gwr.load(from: data)
    let assert Ok(instance) = gwr.create(from: binary)
    let assert Ok(#(_instance, result)) = gwr.call(instance, "fib", [runtime.Integer32(18)])
    let assert [runtime.Integer32(2584)] = result
}

To test the project, you must have Make and Docker (or Podman) installed in your environment. The project has a test suite written in Rust and WebAssembly text format intended to be built for the wasm target; the build process is containerized so there is no need to install additional toolchains.

make test

The above command is equivalent to make build-test-suite followed by gleam test. Of course, once you have built the test suite, you can simply invoke gleam test.

Contributions are welcome! Feel free to submit either issues or PRs, but keep in mind that your code needs to be covered by tests.

GWR source code is avaliable under the MIT license.