From: David Palm <dvdplm@...>
Date: 2008-03-11T21:11:49+09:00
Subject: Re: Combinatorics and permutations? Help?

On Tue, 11 Mar 2008 20:40:11 +0900, William James wrote:
> p [[1,2],[3,4]].inject([[]]){|old,lst|
>   lst.inject([]){|new,e| new + old.map{|c| c.dup << e}}}

awesome. Totally rocks.