As it came up in the discussion at Reddit (http://www.reddit.com/r/haskell/comments/3425pk/refinement_types_as_a_library/cqqni9q http://www.reddit.com/r/haskell

As it came up in the discussion at Reddit (http://www.reddit.com/r/haskell/comments/3425pk/refinement_types_as_a_library/cqqni9q http://www.reddit.com/r/haskell/comments/3425pk/refinement_t...), there at least exists "data-checked" (http://hackage.haskell.org/package/data-checked http://hackage.haskell.org/package/data-checked).