如何在golang中实例化函数类型？

Question

I would like to instantiate a bunch of functions of the same type without having to duplicate their signature. I already have a function type describing that signature (fancyFunc below) and another function consuming arguments of that kind (doFancyStuff below). How would I make something like this work?

package main

import "fmt"

type fancyFunc func(a,b,c int) int

func doFancyStuff(f FancyFunc) int {
    // Do something special with f
    return 42
}

func main() {
    // This works but is rather tedious:
    f1 := func(a,b,c int) int { return a + b + c }

    // I would like to create them like this:
    f2 := fancyFunc{ return a * b * c }

    // Eventually, they are used like this:
    fmt.Println(doFancyStuff(f1))
    fmt.Println(doFancyStuff(f2))
}