:: Either a a -> a package:from-sum

Collapse an Either a a to an a. Defined as fromEither id. Note: Other libraries export this function as fromEither, but our fromEither function is slightly more general.

>>> collapseEither (Right 3)
3

>>> collapseEither (Left "hello")
"hello"

Convert an Either to a Maybe. A Right value becomes Just.

>>> eitherToMaybe $ Right 3
Just 3

A Left value becomes Nothing.

>>> eitherToMaybe $ Left "bye"
Nothing