On 1/20/07, Brian Hulley
Neil Mitchell wrote:
Hi Brian,
Is there any solution that would allow excess laziness to be removed from a Haskell program such that Hask would be a category?
class Seq a where seq :: a -> b -> b
Then you have a different seq based on the types, and it doesn't go wrong. You would probably want deriving Seq support.
This seems an amazingly neat solution to a really terrible problem, so:
1) Does anyone know why this was not used in the first place?
It *was* used before. See section 6.2.7 of the Haskell 1.4 report. It was throw out in Haskell98. I don't remember why though.
2) Would it be good to use this in future versions of Haskell?
3) Is there any practical program which requires the current seq that could not be rewritten to use the typeclass seq?
I'll pass on these two questions. /Josef