On 15/12/2010 14:31, Lennart Augustsson wrote:
Yes, I think there should be a MonadFail distinct from MonadPlus.
Some types, like IO, are not in MonadPlus, but have a special implementation of
the fail method.
Personally, I think fail should just be removed, but that would break existing
code.
The fail method was introduced for the wrong reasons (better error messages was
the excuse).
Which other monads (other than MonadPlus subclasses) define fail?
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