Ilya Basov

package main

import "fmt"

func summ(x, y int) int {
    return x + y
}

func fold(f func(int, int) int, a []int) (res int) {

    for _, v := range a {
        res = f(res, v)
    }

    return
}

func main() {

    a := []int{1, 2, 3, 4, 5}
    f := summ
    fmt.Println(fold(f, a))
}