This bug is already fixed in 5.02.2, which is available now. Simon | -----Original Message----- | From: Ashley Yakeley [mailto:ashley@semantic.org] | Sent: 04 February 2002 02:23 | To: Haskell List | Subject: Implicit Parameter Bug? | | | What's wrong with this? | | f :: ((?param :: a) => b) -> a -> b | f foo a = foo with ?param=a | | g :: (?param :: a) => a | g = ?param | | h :: a -> a | h = f g | | 'ghci -fglasgow-exts' (5.02) gives this error: | | Could not deduce (?param :: a) from the context () | Probable fix: | Add (?param :: a) to the type signature(s) for h | arising from use of `g' at Implicit.hs:10 | In the first argument of `f', namely `g' | In the definition of `h': f g | | 'hugs -98' (Feb 2000) gets as far as this: | | Reading file "/usr/share/hugs98/lib/Prelude.hs": | Reading file "Implicit.hs": | Type checking | | ...and spins there. | | There's a workaround for ghci, but it doesn't help hugs: | | h :: a -> a | h = f (g with ?param = ?param) | | This is very odd, as surely the type of (g with ?param = | ?param) is the | same as the type of g? | | -- | Ashley Yakeley, Seattle WA | | _______________________________________________ | Haskell mailing list | Haskell@haskell.org http://www.haskell.org/mailman/listinfo/haskell |