Hi Everyone, I've uploaded a new version of the permutation library to hackage. Here is the package description: This library includes data types for storing permutations. It implements pure and impure types, the latter which can be modified in-place. The main utility of the library is converting between the linear representation of a permutation to a sequence of swaps. This allows, for instance, applying a permutation or its inverse to an array with O(1) memory use. . Much of the interface for the library is based on the permutation functions in the GNU Scientific Library (GSL). Here's the url: http://hackage.haskell.org/cgi-bin/hackage-scripts/package/permutation Patrick