Sun, 23 Jul 2000 19:38:39 -0700 (PDT), Richard Uhtenwoldt <[EMAIL PROTECTED]> pisze:
> but it would be nice for a small program fragment be able to loop over
> the contents of an input file without resorting to "catch", which is
> more awkard than most constructs. that is easy to achieve: we
> introduce a new primitive, hGetCharMaybe,
Why primitive?
catchEOF:: IO a -> IO (Maybe a)
catchEOF act = liftM Just act `catch`
\e -> if isEOFError e then return Nothing else ioError e
hGetCharMaybe:: IO (Maybe Char)
hGetCharMaybe = catchEOF hGetChar
--
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