First class functions in Go

Question

I come from JavaScript which has first class function support. For example you can:

• pass a function as a parameter to another function
• return a function f

Answer 1

package main

import (
    "fmt"
)

type Lx func(int) int

func cmb(f, g Lx) Lx {
    return func(x int) int {
        return g(f(x))
    }
}

func inc(x int) int {
    return x + 1
}

func sum(x int) int {
    result := 0

    for i := 0; i < x; i++ {
        result += i
    }

    return result
}

func main() {
    n := 666

    fmt.Println(cmb(inc, sum)(n))
    fmt.Println(n * (n + 1) / 2)
}

output:

222111
222111