Golang support using Yaegi

[mliezun]

Issue 359

• Implemented golang support using yaegi
• Golang code used to generate yaegi.wasm:

package main

import (
	"bytes"
	"syscall/js"

	"github.com/traefik/yaegi/interp"
	"github.com/traefik/yaegi/stdlib"
)

func main() {
	idle := make(chan int)

	js.Global().Set("evalGo", js.FuncOf(evalGo))

	<-idle
}

func evalGo(this js.Value, inputs []js.Value) interface{} {
	stdout := bytes.NewBuffer(nil)
	stderr := bytes.NewBuffer(nil)

	i := interp.New(interp.Options{
		Stdout: stdout,
		Stderr: stderr,
	})

	i.Use(stdlib.Symbols)

	var errMessage string
	_, err := i.Eval(inputs[0].String())
	if err != nil {
		errMessage = err.Error()
	}

	return map[string]interface{}{
		"stdout": stdout.String(),
		"stderr": stderr.String(),
		"error":  errMessage,
	}
}

• Compiled with go 1.16: $ GOOS=js GOARCH=wasm go build -o yaegi.wasm main.go
• wasm_exec.js is a standard file got from $ cp "$(go env GOROOT)/misc/wasm/wasm_exec.js"
• Added scripts-src-local and wasm-src-local for local dev testing. (usage of these function should be changed before accepting PR)

[viebel]

Very good job @mliezun !
I cleaned up a bit the code in #394 and merged it to master.
Thank you.

[mliezun]

Great!
I found the blog post in Lobsters. Thank you for mentioning my contribution ✌️

[viebel]

My pleasure @mliezun
Some people asked about the implementation details. Could you describe the process for compiling yaegi into WASM?

[mliezun]

Hi @viebel
The explanation is in the first comment of this PR. You have the go code used and the command used to generate yaegi.wasm just underneath it.
If you never used go before it's easier to use go modules:

• Create new folder called yaegi-js
• Initialize module inside folder $ go mod init yaegi-js
• Copy go code to a new file called main.go
• Compile with $ GOOS=js GOARCH=wasm go build -o yaegi.wasm main.go
  Let me know if you have any trouble running that or you need a more in depth explanation. Im happy to help.