The Ackermann function is a famous function that played a big role in computability theory as the first example of a total computable function that is not primitive recursive.
Since then the function has been a bit simplified but is still of good use. Due to its definition in terms of extremely deep recursion it can be used as a benchmark of a compiler's ability to optimize recursion.
The goal of this kata is to code a function which will be given two inputs, m and n, and will return the Ackermann number A(m,n) defined by:
A(m,n) = n+1 if m=0
A(m,n) = A(m-1,1) if m>0 , n=0
A(m,n) = A(m-1,A(m,n-1)) if m,n > 0
m,n should be non-negative integers, the function should return null (Javascript), None (Python), or nil (Ruby) for other type, non-integer and negative numbers. In C, input is restricted to integer type.