After loading the following script, b = b' && True b' = (if True then f else odd) 1 f _ = True I get the following session: || || || || || || ||__ Hugs 98: Based on the Haskell 98 standard ||___|| ||__|| ||__|| __|| Copyright (c) 1994-2003 ||---|| ___|| World Wide Web: http://haskell.org/hugs || || Report bugs to: hugs-bugs@haskell.org || || Version: November 2003 _______________________________________________ Haskell 98 mode: Restart with command line option -98 to enable extensions Reading file "c:\program files\hugs98\libraries\Hugs\Prelude.hs": Reading file "c:\program files\hugs98\libraries\Prelude.hs": Reading file "C:\Documents and Settings\pepe gallardo\Desktop\pepe.hs": Hugs session for: c:\program files\hugs98\libraries\Hugs\Prelude.hs c:\program files\hugs98\libraries\Prelude.hs C:\Documents and Settings\pepe gallardo\Desktop\pepe.hs Type :? for help Main> b False :: Bool Main> b' Program error: pattern match failure: instShow_v89_v1324 0 b' Regards, Pepe Gallardo