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  • Michael Snoyman's avatar
    d63e1de4
    Add instances for MonadCatch and MonadMask for Either (#56) · d63e1de4
    Michael Snoyman authored and Ryan Scott's avatar Ryan Scott committed 
    Came up in a discussion with @bitonic. There's no downside I can see to
the MonadCatch instance. However, the MonadMask instance is a little bit
more controversial, in that it's not actually doing any masking.
However, it's impossible to know that it's not masking the async
exceptions since there are no side-effects from the Either monad.

Of course, by using unsafePerformIO, we could observe the difference,
but I think that's a valid trade-off.

One final argument against MonadMask for Either: it's probably not
terribly useful.
    d63e1de4
    Add instances for MonadCatch and MonadMask for Either (#56)
    Michael Snoyman authored and Ryan Scott's avatar Ryan Scott committed 
    Came up in a discussion with @bitonic. There's no downside I can see to
the MonadCatch instance. However, the MonadMask instance is a little bit
more controversial, in that it's not actually doing any masking.
However, it's impossible to know that it's not masking the async
exceptions since there are no side-effects from the Either monad.

Of course, by using unsafePerformIO, we could observe the difference,
but I think that's a valid trade-off.

One final argument against MonadMask for Either: it's probably not
terribly useful.
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