MonadFail proposal (MFP): Moving fail out of Monad

Johan Tibell johan.tibell at
Tue Jun 9 22:26:25 UTC 2015

Thanks for putting this together.

The proposal says:

"As a consequence, in current Haskell, you can not use Monad-polymorphic
code safely, because although it claims to work for all Monads, it might
just crash on you. This kind of implicit non-totality baked into the class
is terrible."

Is this actually a problem in practice? Is there any code we can point to
that suffers because of the current state of affairs? Could it be included
in the proposal?
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