Re: Proposal: Add Text.Read.maybeRead :: Read a => String -> Maybe a

On Feb 7, 2008 6:12 PM, Ross Paterson wrote:

I think this is a good idea, though I normally write the equivalent of

maybeRead :: Read a => String -> Maybe a maybeRead s = case reads s of [(x, rest)] | all isSpace rest -> Just x _ -> Nothing

and would prefer not to generalize it to any monad. fail is a wart, not a design pattern.

I also prefer Maybe to fail. Error strings are only useful if you're ignoring them or passing them to the user without interpretation. -- Dave Menendez http://www.eyrie.org/~zednenem/