Go で文字列関数名を使用して関数を動的に呼び出すにはどうすればよいですか?

package main

import "fmt"

func someFunction1(a, b int) int { return a + b }
func someFunction2(a, b int) int { return a - b }

func someOtherFunction(a, b int, f func(int, int) int) int { return f(a, b) }

func main() {
    fmt.Println(someOtherFunction(111, 12, someFunction1))
    fmt.Println(someOtherFunction(111, 12, someFunction2))
}

123
99

m := map[string]func(int, int) int{
    "someFunction1": someFunction1,
    "someFunction2": someFunction2,
}

...

z := someOtherFunction(x, y, m[key])