[Haskell-cafe] Real World Haskell Chapter 19 and GHC 6.10
mpm at alumni.caltech.edu
Thu Oct 22 01:21:12 EDT 2009
Apparently the old exception library had convenience functions like
'arithExceptions' that could be used with 'handleJust'.
handleJust arithExceptions handler thing
With the new module you can write something like this (I determined this
arithExceptionTester :: ArithException -> IO ()
arithExceptionTester = Just ()
handleJust arithExceptionTester handler thing
(1) Is there a better way to do things?
(2) I don't understand quite how the type system works. Somehow, on
exceptions that aren't arithmetic, arithExceptionTester returns Nothing or
at least behaves that way. Yet I didn't write any code to do that. Can
someone explain this?
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