Because the fail method is an abomination that should never have been
included in the Monad class.
2008/2/7 Jeff Polakow
Hello,
Why not allow an arbitrary monad?
readM :: (Monad m, Read a) => String -> String -> m a readM errMsg s = case reads s of [(x, "")] -> return x _ -> fail errMsg
-Jeff
libraries-bounces@haskell.org wrote on 02/07/2008 01:46:48 PM:
This function is typically defined once per project. So its about time this safe variant of 'read' made it into the base.
maybeRead :: Read a => String -> Maybe a maybeRead s = case reads s of [(x, "")] -> Just x _ -> Nothing
Consideration period: 1 week.
Patch to Text.Read attached.
[attachment "maybeRead.patch" deleted by Jeff Polakow/db/dbcom] _______________________________________________ Libraries mailing list Libraries@haskell.org http://www.haskell.org/mailman/listinfo/libraries
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