On Tue, Jan 30, 2007 at 05:07:18PM +0000, Chris Kuklewicz wrote:
I agree that the change improves the consistence of semantics.
You should amend the proposal to also explain how to restore the previous strictness using 'seq'.
I'm not sure what you mean?
And if StateT is to be fixed, then the same fix should be applied to WriterT, as shown in http://haskell.org/haskellwiki/New_monads/LazyWriterT
And the same fix looks like it should be applied to RWST.
ErrorT I believe is supposed to be Strict, so it can stop when a (Left _) is found.
Hmm, now I look closer there are a number of other places that look like they could benefit from a ~. I've attached a new patch and unified diff of them all to the proposal http://hackage.haskell.org/trac/ghc/ticket/1127 and changed the description to match its increased scope. The changes only affect transformers except for: listens :: (MonadWriter w m) => (w -> b) -> m a -> m (a, b) listens f m = do - (a, w) <- listen m + ~(a, w) <- listen m return (a, f w) in Control/Monad/Writer.hs Thanks Ian