Golang function and function variable semantics

Question

Why can't I define a recursive function as a variable? I seem to be able to define arbitrary functions except when they recurse.

This is legal:

func f(i int) int {     if i == 0 {         return 1     }     return i * f(i-1) }  func main() {     fmt.Println(f(2)) } 

This is illegal:

var f func(int) int = func(i int) int {     if i == 0 {         return 1     }     return i * f(i-1) }  func main() {     fmt.Println(f(2)) } 

This is legal and I'm guessing it is just because you can figure out f after initialization:

func main() {     var f *func(int) int;     t := func(i int) int {         if i == 0 {             return 1         }         return i * (*f)(i-1)     }     f = &t     fmt.Println((*f)(2)) } 

So it looks like it comes down to function and variable declarations of a function type are treated differently though from the reading the documentation I wouldn't expect that to be the case. Did I miss the part of the documentation detailing this?

I would expect the illegal case to work just because it works in other languages. Like in JavaScript:

(function () {   var f = function (i) {     if (i == 0) {       return 1;     }     return i * f(i - 1);   };    console.log(f(2)); })(); 

Answer 1

The below code would be the preferred way of doing what you describe. Note that you do not have to create an additional variable, nor do you have a pointer to a function:

package main  import "fmt"  func main() {     var f func(int) int     f = func(i int) int {         if i == 0 {             return 1         }         return i * f(i-1)     }     fmt.Println(f(2)) }