2009/2/9 Gregg Reynolds <d...@mobileink.com>: > > Right; "implementation of IO" means also an implementation for >>=, not just > the IO operators. I hadn't thought about that but it's hugely important for > the exposition of monads and IO. > > "The IO Char indicates that getChar, when invoked, performs some action > which returns a character." (Gentle Intro, typical of many expositions.)
In this case, I think "invoked" is shorthand for "interpreted by the runtime system". > That, plus the form of \x -> putChar x used with >>=, plus the fact that one > can do getChar at the ghci command line, plus all the other stuff - it all > adds up to exasperation. It's worth noting that ghci, unlike Haskell itself, *does* treat IO specially. It checks the type of the expression you've entered, and behaves differently depending on whether it's equal to a, IO a, or IO (). interp[ e :: IO () ] = e interp[ e :: IO a ] = e >>= print interp[ e :: a ] = print e This is convenient for users, but it has nothing to do with the semantics of Haskell. -- Dave Menendez <d...@zednenem.com> <http://www.eyrie.org/~zednenem/> _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
