Factorial in Cat

Example for versions Online Cat 1.3

This example uses recursive factorial definition, and works in a similar way to Fibonacci numbers example. 

define fact {
    dup 1 <= 
        [pop 1]
        [dup 1 - fact *]
    if
}

    0
    [dup write "! = " write dup fact writeln inc]
    [dup 16 lteq]
while