[Go] untype type

Reference:
https://groups.google.com/g/golang-nuts/c/9EVmGFVoawg/m/nYXYaUcpCgAJ

Untyped bool, int, etc are the types of untyped constants:
https://golang.org/ref/spec#Constants

const i = 42 // i is untyped 

int const j = int(42) // j is int

var f float64 = i // ok because i is untyped int

var g float64 = j // compile error, type mismatch