philip.weaver:
> >
> > 1. How do I catch the exception that is raised from "read"?
> >
> I think you want readIO, which yields a computation in the IO monad,
> so it can be caught.
Ah, that's a third option, sequence the effect using readIO,
import System.IO
import qualified Control.Exception as C
main = do
x <- getNum
print x
getNum :: IO Integer
getNum = do
y <- maybeRead
case y of
Nothing -> getNum
Just n -> return n
maybeRead :: Read a => IO (Maybe a)
maybeRead = C.catch
(do x <- getLine
n <- readIO x
return (Just n)) -- ensure any exception is thrown here
(const (return Nothing))
-- Don
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