How to self reference a function?

Question

Below code in python:

def print_all(x):
   print(x)
   return print_all

---

allows to call print_all(1)(2) or print_all(1)(2)(3)(4)

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Edit

Another example in python:

def print_sums(x):
   print(x)
   def next_sum(y):
      return print_sums(x+y)
   return next_sum

print_sums(1)(3)(5)

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which maps to syntax:

package main

import "fmt"

type printsumfunctype func(x int) printsumfunctype

func printSums(x int) printsumfunctype {
    fmt.Println(x)
    var nextSum func(y int) printsumfunctype
    nextSum = func(y int) printsumfunctype {
        return printSums(x + y)
    }
    return nextSum
}

func main() {
    printSums(1)(2)(3)
}

In GoLang, function is first class

1) What is the syntax to self reference a function in GoLang?

2) What is the preferred naming convention to define types like printsumfunctype?

Answer 1

You define a recursive function type:

type Printer func(interface{}) Printer

func printAll(x interface{}) Printer {
    fmt.Println(x)
    return printAll
}

func main() {
    printAll(1)("Hello")
}

For the new code, you would write

type Sink func(int) Sink // not really different, is it?

func printSums(x int) Sink {
    fmt.Println(x)
    return func(y int) Sink {
        return printSums(x + y)
    }
}

A useful naming convention is to just name the types after their functions. In both of these cases, Printer (basically function verb + "er") works. Or, the more generic term Sink also fits, as it's a black hole that you can just keep dumping items into. I don't think there's any rule for it; these types aren't very common. Just pick a descriptive name.