Re: Re: [Haskell-cafe] Aren't type system extensions fun? [Further analysis]

Roberto Zunino-2 wrote:

Alas, for code like yours: foo = \f -> (f 'J', f True)

there are infinite valid types too: (forall a. a -> Int) -> (Int, Int) (forall a. a -> Char)-> (Char, Char) (forall a. a -> (a,a)) -> ((Char,Char),(Bool,Bool)) ...

and it is much less clear if a "best", most general type exists at all.

How about foo :: (exists. m :: * -> *. forall a. a -> m a) -> (m Char, m Bool) Not quite Haskell, but seems to cover all of the examples you gave. -- Kim-Ee -- View this message in context: http://www.nabble.com/Aren%27t-type-system-extensions-fun--tp17479349p175312... Sent from the Haskell - Haskell-Cafe mailing list archive at Nabble.com.