Try out go plugin package

a.go

package main

import (
	"fmt"
)

// F is to be loaded and called from main().
func F() {
	fmt.Println(`This is a function in "a.go"`)
}

b.go

package main

import "fmt"

// F is to be loaded and called from main().
func F() {
	fmt.Println(`This is a function "b.go"`)
}

main.go

package main

import (
	"fmt"
	"os"
	"plugin"
)

func main() {
	if len(os.Args) < 2 {
		fmt.Println(help())
		os.Exit(1)
	}

	p, err := plugin.Open(os.Args[1] + ".so")
	if err != nil {
		fmt.Fprintf(os.Stderr, "Unexpected command: %s", err)
		os.Exit(1)
	}

	f, err := p.Lookup("F")
	if err != nil {
		fmt.Fprintf(os.Stderr, "Function F not found: %s", err)
		os.Exit(1)
	}

	f.(func())()
}

func help() string {
	return ""
}

1. build a.go and b.go with plugin mode

$ go build -buildmode=plugin a.go
$ go build -buildmode=plugin b.go

2. build main.go

$ go build main.go

3. run main with arguments

$ ./main a
This is a function in "a.go"

$ ./main b
This is a function in "b.go"