go.mod

module github.com/kyleconroy/wasmtimetest

go 1.18

require github.com/bytecodealliance/wasmtime-go v0.37.0

main.go

package main

import (
	"fmt"

	"github.com/bytecodealliance/wasmtime-go"
)

func main() {
	// Almost all operations in wasmtime require a contextual `store`
	// argument to share, so create that first
	store := wasmtime.NewStore(wasmtime.NewEngine())

	// Compiling modules requires WebAssembly binary input, but the wasmtime
	// package also supports converting the WebAssembly text format to the
	// binary format.
	wasm, err := wasmtime.Wat2Wasm(`
      (module
        (import "" "hello" (func $hello))
        (func (export "run")
          (call $hello))
      )
    `)
	check(err)

	// Once we have our binary `wasm` we can compile that into a `*Module`
	// which represents compiled JIT code.
	module, err := wasmtime.NewModule(store.Engine, wasm)
	check(err)

	// Our `hello.wat` file imports one item, so we create that function
	// here.
	item := wasmtime.WrapFunc(store, func() {
		fmt.Println("Hello from Go!")
	})

	// Next up we instantiate a module which is where we link in all our
	// imports. We've got one import so we pass that in here.
	instance, err := wasmtime.NewInstance(store, module, []wasmtime.AsExtern{item})
	check(err)

	// After we've instantiated we can lookup our `run` function and call
	// it.
	run := instance.GetFunc(store, "run")
	if run == nil {
		panic("not a function")
	}
	_, err = run.Call(store)
	check(err)
}

func check(e error) {
	if e != nil {
		panic(e)
	}
}