GeezerVison

Go supports recursive functions. Here’s a classic example.

package main

import "fmt"

This fact function calls itself until it reaches the base case of fact(0).

func fact(n int) int {
    if n == 0 {
        return 1
    }
    return n * fact(n-1)
}

func main() {
    fmt.Println(fact(7))

Anonymous functions can also be recursive, but this requires explicitly declaring a variable with var to store the function before it’s defined.

    var fib func(n int) int

    fib = func(n int) int {
        if n < 2 {
            return n
        }

Since fib was previously declared in main, Go knows which function to call with fib here.

        return fib(n-1) + fib(n-2)
    }

    fmt.Println(fib(7))
}

$ go run recursion.go 
5040
13