Formerly clojure.contrib.combinatorics.

Efficient, functional algorithms for generating lazy sequences for common combinatorial functions.

• (combinations items n) - A lazy sequence of all the unique ways of taking n different elements from items.

  Example: (combinations [1 2 3] 2) -> ((1 2) (1 3) (2 3))

• (subsets items) - A lazy sequence of all the subsets of items (but generalized to all sequences, not just sets).

  Example: (subsets [1 2 3]) -> (() (1) (2) (3) (1 2) (1 3) (2 3) (1 2 3))
  

• (cartesian-product & seqs) - Takes any number of sequences as arguments, and returns a lazy sequence of all the ways to take one item from each seq.

  Example: (cartesian-product [1 2] [3 4]) -> ((1 3) (1 4) (2 3) (2 4))
  

• (selections items n) - A lazy sequence of all the ways to take n (possibly the same) items from the sequence of items.

  Example: (selections [1 2] 3) -> ((1 1 1) (1 1 2) (1 2 1) (1 2 2) (2 1 1) (2 1 2) (2 2 1) (2 2 2))

• (permutations items) - A lazy sequence of all the permutations of items.

  Example: (permutations [1 2 3]) -> ((1 2 3) (1 3 2) (2 1 3) (2 3 1) (3 1 2) (3 2 1))
  

Distributed under the Eclipse Public License, the same as Clojure.