generics.go

package main

import (
	"fmt"
)

type Set map[interface{}]bool

func Intersection(s1, s2 Set) Set {
	rs := Set{}
	for k := range s1 {
		if _, ok := s2[k]; ok {
			rs[k] = true
		}
	}

	return rs
}

func main() {
	s1 := Set{
		1: true,
		2: true,
		3: true,
		"foo": true,
	}

	s2 := Set{
		2: true,
		3: true,
		4: true,
		"foo": true,
	}

	fmt.Println(Intersection(s1,s2))
}

outputs:

map[2:true 3:true foo:true]