Problem Statement

Most programming languages have a built-in implementation of exponentiation.

Re-implement integer exponentiation for both   intint   and   floatint   as both a procedure,   and an operator (if your language supports operator definition). If the language supports operator (or procedure) overloading, then an overloaded form should be provided for both   intint   and   floatint   variants.

Let's start with the solution:

pow(X, Y) when Y < 0 ->
    1/pow(X, -Y);
pow(X, Y) when is_integer(Y) ->
    pow(X, Y, 1).

pow(_, 0, B) ->
    B;
pow(X, Y, B) ->
    B2 = if Y rem 2 =:= 0 -> B; true -> X * B end,
    pow(X * X, Y div 2, B2).