Name Math::Cartesian::Product - Generate the cartesian product of zero or more lists. Synopsis use Math::Cartesian::Product; cartesian {say "@_"} [qw(a b c)], [1..2]; # a 1 # a 2 # b 1 # b 2 # c 1 # c 2 Description Generate the cartesian product of zero or more lists. Given two lists, say: [a,b] and [1,2,3], the cartesian product is the set of all possible ordered pairs: (a,1), (a,2), (a,3), (b,1), (b,2), (b,3) which select their first element from all the possibilities listed in the first list, and select their second element from all the possibilities in the second list. The idea can be generalized to any number of lists. In particular, the cartesian product of zero lists is the empty set, as is the cartesian product of any set of lists which contain a list with no elements. "cartesian()" takes the following parameters: 1. A block of code to process each selection of list elements. 2. zero or more lists. "cartesian()" returns an array of references to all the pairs (more generally n-tuples) produced, each pair being held as an array. "cartesian()" croaks if you try to form the cartesian product of something other than a list of things. The cartesian product of lists A,B,C is associative, that is: (A X B) X C = A X (B X C) "cartesian()" respects associativity by allowing you to include a cartesian product produced by an earlier call to "cartesian()" in the set of lists whose cartesian product is to be formed. my $a = [qw(a b)]; my $b = [cartesian {} $a, $a; ok 16 == cartesian {} $b, $b; # a a a a # a a a b # a a b a # ... "cartesian()" is easy to use and fast. It is written in 100% Pure Perl. Export The "cartesian()" function is exported. Installation Standard Module::Build process for building and installing modules: perl Build.PL ./Build ./Build test ./Build install Or, if you're on a platform (like DOS or Windows) that doesn't require the "./" notation, you can do this: perl Build.PL Build Build test Build install Author PhilipRBrenan@handybackup.com http://www.handybackup.com See Also Copyright Copyright (c) 2009 Philip R Brenan. This module is free software. It may be used, redistributed and/or modified under the same terms as Perl itself.