How To Cube A Number In Factor?

Question

I'm playing with Factor trying to get a little understanding of concatenative programming. Writing a word to square a number is trivial:

: square ( n -- n ) dup * ;

But for the life of me I can't seem to figure out how to cube a number:

: cube ( n -- n ) * * ;  ! Form a

Doesn't work because the inferred stack effect is ( x x x -- x ) Similarly

: cube ( n -- n ) dup * * ; ! Form b

also fails.

If I were to hard code a cube I would do something like this:

3 3 * 3 *

Which is why my naive guess would be form b.

As I say I'm just playing with Factor and would love to know what I'm missing here--but it's mostly for my curiosity.

Answer 1

There is a builtin word for that:

IN: scratchpad 3 3 ^ .
27

Or if you want to write the word yourself:

: pow ( x n -- y ) 1 - over '[ _ * ] times ;
IN: scratchpad 5 3 pow .
125

You could also formulate cube using square:

: cube ( n -- n' ) dup square * ;
IN: scratchpad 6 cube .
216