I don't know much about type families, but I recall this: http://ghc.haskell.org/trac/ghc/ticket/5321
The bug is marked as fixed, but perhaps behaviour you observed shows that there are other cases where constraqint solver is slow. I'd consider reporting this as GHC bug. Janek _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
