Control.Applicative.Lift

Applicative functor formed by adding pure computations to a given applicative functor.

Projection to the other functor.

Apply a transformation to the other computation.

Eliminator for Lift.

• elimLift f g . pure = f

• elimLift f g . Other = g

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 ExceptT from Control.Monad.Trans.Except, these computations continue after an error, collecting all the errors.

• pure f <*> pure x = pure (f x)

• pure f <*> failure e = failure e

• failure e <*> pure x = failure e

• failure e1 <*> failure e2 = failure (e1 <> e2)

Extractor for computations with accumulating errors.

• runErrors (pure x) = Right x

• runErrors (failure e) = Left e

Report an error.

Convert from Either to Errors (inverse of runErrors).