Hi, With the code:

import qualified Data.Map as Map data Test = Map.Map Int Int

There is no error at compile time by Hugs. There is in GHC: test.hs:6:12: Not in scope: data constructor `Map.Map' Of course, the GHC error message is not really very good, but Hugs compiles it fine - I have no idea what the runtime behaviour is. I guess this is an invalid Haskell program, and Hugs is at fault? Thanks Neil