Dear Haskell Folks This is to announce the availability of indexed data types, a modest extension of our earlier proposal for associated data types[1], in GHC's development version. Detailed information on where to get the right GHC and how to use indexed types is available from the Haskell wiki: http://haskell.org/haskellwiki/GHC/Indexed_types This is an experimental feature and any feedback is greatly appreciated. NB: The implementation of associated type *synonyms* is *not* complete yet. We are working on this now. Happy Hacking! Manuel [1] http://www.cse.unsw.edu.au/~chak/papers/CKPM05.html