Doug Ransom writes: [...]
2. It seems to me that the Maybe monad is a poor substitute for exception handling because the functions that raise errors may not necessarily support it.
It sometimes helps to write such functions for monads in general, rather than for Maybe in particular. Here's an example adapted from the standard List module: findIndex :: (a -> Bool) -> [a] -> Maybe Int findIndex p xs = case findIndices p xs of (i:_) -> Just i [] -> Nothing It generalises to this: findIndex :: Monad m => (a -> Bool) -> [a] -> m Int findIndex p xs = case findIndices p xs of (i:_) -> return i [] -> fail "findIndex: no match" The price of the generalisation is that you may need to add some type signatures to resolve any new overloading at the top level of the module. Regards, Tom