Functions as values

As with almost everything inGo, functions are also just values. They can be assigned to variables asfollows:

import "fmt"
func main() {
    a := func() { 1
        fmt.Println("Hello")
    } 2
    a() 3
}

a is defined as an anonymous (nameless) function 1.Note the lack of parentheses () after a. If there were, that would be to call_some function with the name a before we have defined what a is. Once a isdefined, then we can _call it, 3.

Functions–as–values may be used in other places, for example maps. Here weconvert from integers to functions:

var xs = map[int]func() int{
    1: func() int { return 10 },
    2: func() int { return 20 },
    3: func() int { return 30 },
}

Note that the final comma on second to last line is mandatory.

Or you can write a function that takes a function as its parameter, for examplea Map function that works on int slices. This is left as an exercise for thereader; see the exercise .