从Golang中的功能列表中选择一个功能

Basically if I have a slice or array of any arbitrary functions, how can I select only the ones that return int, or select only the ones that take ints?

I figured that I would need to use the reflect package, but just reading the docs didn't really help me figure out exactly how to do it.

This program prints the functions taking an int as parameter or returning an int :

package main

import (
    "fmt"
    "reflect"
)

func main() {
    funcs := make([]interface{}, 3, 3) // I use interface{} to allow any kind of func
    funcs[0] = func (a int) (int) { return a+1} // good
    funcs[1] = func (a string) (int) { return len(a)} // good
    funcs[2] = func (a string) (string) { return ":("} // bad
    for _, fi := range funcs {
        f := reflect.ValueOf(fi)
        functype := f.Type()
        good := false
        for i:=0; i<functype.NumIn(); i++ {
            if "int"==functype.In(i).String() {
                good = true // yes, there is an int among inputs
                break
            }
        }
        for i:=0; i<functype.NumOut(); i++ {
            if "int"==functype.Out(i).String() {
                good = true // yes, there is an int among outputs
                break
            }
        }
        if good {
            fmt.Println(f)
        }
    }
}

I think the code is self explanatory