Tom Shackell wrote:
The value of World comes up in only two places that I know of.
Ah I lie, the final use of World is in the Show instance of the IO Monad. instance (Show a) => Show (IO a) where ... showsType (IO fta) = showString "(IO " . showsType ta . showChar ')' where (_E ta) = fta World Interestingly this applies World to the IO action, however, since the only thing that is done with the result is 'showsType' the computation is never actually evaluated (since you don't need to evaluate it to know its type). Though why this doesn't just use unsafePerformIO I don't know ... showsType io = showString "(IO " . showsType a . showChar ')' where a = unsafePerformIO io This would work just as well. *shrugs* Yhc has quite a lot of historical carry-overs from nhc98 :) Cheers Tom