fromRight package:rebase

fromRight :: b -> Either a b -> b
rebase Rebase.Prelude
Return the contents of a Right-value or a default value otherwise.

Examples

Basic usage: 
>>> fromRight 1 (Right 3)
3

>>> fromRight 1 (Left "foo")
1
fromRight' :: Either a b -> b
rebase Rebase.Prelude
Extracts the element out of a Right and throws an error if its argument take the form Left _. Using Control.Lens: 
fromRight' x ≡ x^?!_Right

>>> fromRight' (Right 12)
12