Adding a new kind of pure computation to an applicative functor.
Applicative functor formed by adding pure computations to a given applicative functor.
An applicative functor that collects a monoid (e.g. lists) of errors.
A sequence of computations fails if any of its components do, but
unlike monads made with
ErrorT from Control.Monad.Trans.Error,
these computations continue after an error, collecting all the errors.