On 12 November 2012 13:25, Henning Thielemann
I don't think of changing it. We could provide a package that exports "the right 'seq'" and then encourage people to use this instead of Prelude.seq.
I think I like this idea. So the package would export something like: module Control.Seq where import Prelude hiding (seq) import GHC.Base hiding (seq) class WHNFData a where rwhnf :: a -> () instance WHNFData [a] where rwhnf [] = () rwhnf (_:_) = () -- and all the others... seq :: WHNFData a => a -> b -> b seq a b = case rwhnf a of () -> b ($!) :: WHNFData a => (a -> b) -> a -> b f $! x = x `seq` f x force :: WHNFData a => a -> a force x = x `seq` x -- Doesn't type check unfortunately -- since the b in seq :: a -> b -> b is of kind * and not #: -- evaluate :: WHNFData a => a -> IO a -- evaluate x = IO (\s -> x `seq` (# s, x #)) However, I still think it doesn't hurt to add the strict versions now. And then in the future possibly change the whole base library at once (and other libraries like containers) to support the Seq class. Bas