I uploaded a new fixed length list library to hackage: http://hackage.haskell.org/package/fixed-list Its main advantages are: Very easy to use. Almost entirely Haskell98 (the non Haskell98 pieces are not critical, just nice) The datatype is a member of Foldable, Traverable, Applicative, Monad, etc... Then length of the list is encoded in the type in a natural way. Comments/critiques/suggestions welcome :) - Job