On Tue, Nov 17, 2009 at 8:48 PM, Dean Herington
The documentation claim that "The default implementation of 'deepseq' is simply 'seq'" is not exactly right, as `deepseq` and `seq` have different signatures. Which raises the more interesting question: Why did you choose a different signature? And, would a version of `seq` with the same signature as `deepseq` be useful?
The situation is analogous to, say, "null" having this signature: null :: [a] -> Bool Instead of this one: null :: [a] -> b -> b -> b Or the recent famous debate about returning Maybe a vs. Monad m => m a for failure. If we have seq' :: a -> (), then we have seq = m . seq' where m () = id And of course we can go the other way too. So it is a question of taste. deepseq is simpler by at least two standards: it is not polymorphic and it has only one argument. There are exactly two values of both () and forall b. b -> b, but that fact is more obvious of the former (IMO). I think it is the right choice. Luke