Run roc with go

main.go

package main

import (
	"context"
	_ "embed"
	"fmt"
	"log"
	"os"

	"github.com/tetratelabs/wazero"
	"github.com/tetratelabs/wazero/api"
	"github.com/tetratelabs/wazero/imports/wasi_snapshot_preview1"
)

//go:embed rocLovesWebAssembly.wasm
var wasm []byte

func main() {
	if err := run(); err != nil {
		log.Println(err)
		os.Exit(1)
	}
}

func run() error {
	ctx := context.Background()

	runtime := wazero.NewRuntime(ctx)
	defer runtime.Close(ctx)

	wasi_snapshot_preview1.MustInstantiate(ctx, runtime)

	// Instantiate a Go-defined module named "env" that exports a function to
	// log to the console.
	_, err := runtime.NewHostModuleBuilder("env").
		NewFunctionBuilder().
		WithFunc(logString).
		Export("js_display_roc_string").
		NewFunctionBuilder().
		WithFunc(rocPanic).
		Export("roc_panic").
		Instantiate(ctx)
	if err != nil {
		return fmt.Errorf("create host module: %w", err)
	}

	// Instantiate a WebAssembly module that imports the "log" function defined
	// in "env".
	if _, err = runtime.Instantiate(ctx, wasm); err != nil {
		return fmt.Errorf("instantiate: %w", err)
	}

	return nil
}

func logString(_ context.Context, m api.Module, offset, byteCount uint32) {
	buf, ok := m.Memory().Read(offset, byteCount)
	if !ok {
		fmt.Printf("Memory.Read(%d, %d) out of range", offset, byteCount)
		os.Exit(2)
	}
	fmt.Print(string(buf))
}

func rocPanic(_ context.Context, m api.Module, offset, byteCount uint32) {
	panic("TODO")
}