Hello,
readM with fail defaults to ioError for almost all Monads, and so admits many dangerous programs, which is against the intent of the proposal in the first place.
ioError is only in the IO monad and is catchable. I think the problem is when fail defaults to error which can be anywhere and is not catchable.
It seems with Conor's suggestion of a
maybeReturn :: MonadPlus m => Maybe a -> m a maybeReturn = maybe mzero return
we can still have the by-default-safe maybeRead, that doesn't admit exception throwing opportunities.
Isn't the MonadPlus approach also by-default-safe? -Jeff --- This e-mail may contain confidential and/or privileged information. If you are not the intended recipient (or have received this e-mail in error) please notify the sender immediately and destroy this e-mail. Any unauthorized copying, disclosure or distribution of the material in this e-mail is strictly forbidden.