On Mon, 2009-03-16 at 14:17 -0700, Jonathan Cast wrote: > On Mon, 2009-03-16 at 22:12 +0100, Henning Thielemann wrote: > > On Sun, 15 Mar 2009, Claus Reinke wrote: > > > > > import Data.IORef > > > import Control.Exception > > > > > > main = do > > > r <- newIORef 0 > > > let v = undefined > > > handle (\(ErrorCall _)->print "hi">>return 42) $ case f v of > > > 0 -> return 0 > > > n -> return (n - 1) > > > y <- readIORef r > > > print y > > > > I don't see what this has to do with strictness. It's just the hacky > > "exception handling" which allows to "catch" programming errors. > > And which I have a sneaking suspicion actually *is* `unsafe'. Or, at > least, incapable of being given a compositional, continuous semantics.
See this paper: "A semantics for imprecise exceptions" http://research.microsoft.com/en-us/um/people/simonpj/papers/imprecise-exn.htm Basically if we can only catch exceptions in IO then it doesn't matter, it's just a little extra non-determinism and IO has plenty of that already. Duncan _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
