Hello! Recently I was trying to write a variadic function composition operator in Haskell. I managed to produce a version with such an interface: runF (compose f1 f2 f3 ... fn) == f1 . f2 . f3 . ... . fn I believe it is impossible to remove 'runF' without loosing generality and introducing ambiguities. But that's not my question. I noticed that Hugs can instantly infer the nice type for result of composition, but GHC keeps the huge typeclass context to the last moment. __ __ __ __ ____ ___ _________________________________________ || || || || || || ||__ 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 _________________________________________ Hugs mode: Restart with command line option +98 for Haskell 98 mode Type :? for help Prelude> :l Comp Comp> :t runF (compose succ (+ 1) succ read) runF (compose succ (flip (+) 1) succ read) :: (Num a, Enum a, Read a) => [Char] -> a Comp> :t runF (compose id id id id) runF (compose id id id id) :: a -> a ___ ___ _ / _ \ /\ /\/ __(_) / /_\// /_/ / / | | GHC Interactive, version 6.2.1, for Haskell 98. / /_\\/ __ / /___| | http://www.haskell.org/ghc/ \____/\/ /_/\____/|_| Type :? for help. Loading package base ... linking ... done. Prelude> :l Comp Compiling Comp ( Comp.hs, interpreted ) Ok, modules loaded: Comp. *Comp> :t runF (compose succ (+ 1) succ read) runF (compose succ (+ 1) succ read) :: forall a b a1 a2 a3 a4. (MkComp (a1 -> a1) ((a2 -> a2) -> (a3 -> a3) -> (String -> a4) -> F a b), Enum a1, Num a2, Enum a3, Read a4) => a -> b *Comp> runF (compose succ (+ 1) succ read) "13123" :: Int 13126 *Comp> :t runF (compose id id id id) runF (compose id id id id) :: forall a b a1 a2 a3 a4. (MkComp (a1 -> a1) ((a2 -> a2) -> (a3 -> a3) -> (a4 -> a4) -> F a b)) => a -> b *Comp> let f = runF (compose id id id id) *Comp> :t f f :: forall b. b -> b Is this a known feature of GHC ? Best regards, Tom -- .signature: Too many levels of symbolic links