eitherToThrow

[phadej]

I often look for

eitherToThrow :: (MonadThrow m, Exception e) => Either e a -> m a
eitherToThrow (Right x) = pure x
eitherToThrow (Left e)  = throwM e

is it there already, in more general version?

There is eitherToError in either, but it's a bit different.

[ocharles]

I usually call this liftEither and find it very useful.

Edit: actually my liftEither is much more like eitherToError, so maybe that's not a great name here.

[snoyberg]

I follow this pattern a lot via either throwM pure. My only concern is that the combinator doesn't add match help vs the three-word version I just provided.

[ocharles]

It explicitly spells out what it's doing, rather than making me think. You can only parse either throwM pure so quickly because you have seen it so often, imo.

[jmcardon]

I'd like to submit a PR for this if you all are for it. I was looking for something around liftEither or fromEither and couldn't find it.

[domenkozar]

Same here today. https://twitter.com/domenkozar/status/1063147657139503104

@roberth called it escalate:

escalate :: (Exception exc, MonadThrow m) => Either exc a -> m a
escalate = escalateAs id

escalateAs :: (Exception exc, MonadThrow m) => (l -> exc) -> Either l a -> m a
escalateAs f = either (throwM . f) pure