Control.Applicative.Lift

Description

Adding a new kind of pure computation to an applicative functor.

Lifting an applicative

data Lift f a Source

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

Constructors

 Pure a Other (f a)
Instances
Functor f => Functor (Lift f)
Instance details

Defined in Control.Applicative.Lift

Methods

fmap :: (a -> b) -> Lift f a -> Lift f b Source

(<\$) :: a -> Lift f b -> Lift f a Source

Applicative f => Applicative (Lift f)

A combination is `Pure` only if both parts are.

Instance details

Defined in Control.Applicative.Lift

Methods

pure :: a -> Lift f a Source

(<*>) :: Lift f (a -> b) -> Lift f a -> Lift f b Source

liftA2 :: (a -> b -> c) -> Lift f a -> Lift f b -> Lift f c Source

(*>) :: Lift f a -> Lift f b -> Lift f b Source

(<*) :: Lift f a -> Lift f b -> Lift f a Source

Foldable f => Foldable (Lift f)
Instance details

Defined in Control.Applicative.Lift

Methods

fold :: Monoid m => Lift f m -> m Source

foldMap :: Monoid m => (a -> m) -> Lift f a -> m Source

foldr :: (a -> b -> b) -> b -> Lift f a -> b Source

foldr' :: (a -> b -> b) -> b -> Lift f a -> b Source

foldl :: (b -> a -> b) -> b -> Lift f a -> b Source

foldl' :: (b -> a -> b) -> b -> Lift f a -> b Source

foldr1 :: (a -> a -> a) -> Lift f a -> a Source

foldl1 :: (a -> a -> a) -> Lift f a -> a Source

toList :: Lift f a -> [a] Source

null :: Lift f a -> Bool Source

length :: Lift f a -> Int Source

elem :: Eq a => a -> Lift f a -> Bool Source

maximum :: Ord a => Lift f a -> a Source

minimum :: Ord a => Lift f a -> a Source

sum :: Num a => Lift f a -> a Source

product :: Num a => Lift f a -> a Source

Traversable f => Traversable (Lift f)
Instance details

Defined in Control.Applicative.Lift

Methods

traverse :: Applicative f0 => (a -> f0 b) -> Lift f a -> f0 (Lift f b) Source

sequenceA :: Applicative f0 => Lift f (f0 a) -> f0 (Lift f a) Source

mapM :: Monad m => (a -> m b) -> Lift f a -> m (Lift f b) Source

sequence :: Monad m => Lift f (m a) -> m (Lift f a) Source

Eq1 f => Eq1 (Lift f)
Instance details

Defined in Control.Applicative.Lift

Methods

liftEq :: (a -> b -> Bool) -> Lift f a -> Lift f b -> Bool Source

Ord1 f => Ord1 (Lift f)
Instance details

Defined in Control.Applicative.Lift

Methods

liftCompare :: (a -> b -> Ordering) -> Lift f a -> Lift f b -> Ordering Source

Instance details

Defined in Control.Applicative.Lift

Methods

Show1 f => Show1 (Lift f)
Instance details

Defined in Control.Applicative.Lift

Methods

liftShowsPrec :: (Int -> a -> ShowS) -> ([a] -> ShowS) -> Int -> Lift f a -> ShowS Source

liftShowList :: (Int -> a -> ShowS) -> ([a] -> ShowS) -> [Lift f a] -> ShowS Source

Alternative f => Alternative (Lift f)

A combination is `Pure` only either part is.

Instance details

Defined in Control.Applicative.Lift

Methods

empty :: Lift f a Source

(<|>) :: Lift f a -> Lift f a -> Lift f a Source

some :: Lift f a -> Lift f [a] Source

many :: Lift f a -> Lift f [a] Source

(Eq1 f, Eq a) => Eq (Lift f a)
Instance details

Defined in Control.Applicative.Lift

Methods

(==) :: Lift f a -> Lift f a -> Bool

(/=) :: Lift f a -> Lift f a -> Bool

(Ord1 f, Ord a) => Ord (Lift f a)
Instance details

Defined in Control.Applicative.Lift

Methods

compare :: Lift f a -> Lift f a -> Ordering

(<) :: Lift f a -> Lift f a -> Bool

(<=) :: Lift f a -> Lift f a -> Bool

(>) :: Lift f a -> Lift f a -> Bool

(>=) :: Lift f a -> Lift f a -> Bool

max :: Lift f a -> Lift f a -> Lift f a

min :: Lift f a -> Lift f a -> Lift f a

Instance details

Defined in Control.Applicative.Lift

Methods

(Show1 f, Show a) => Show (Lift f a)
Instance details

Defined in Control.Applicative.Lift

Methods

showsPrec :: Int -> Lift f a -> ShowS Source

show :: Lift f a -> String Source

showList :: [Lift f a] -> ShowS Source

unLift :: Applicative f => Lift f a -> f a Source

Projection to the other functor.

mapLift :: (f a -> g a) -> Lift f a -> Lift g a Source

Apply a transformation to the other computation.

elimLift :: (a -> r) -> (f a -> r) -> Lift f a -> r Source

Eliminator for `Lift`.

• `elimLift f g . pure = f`
• `elimLift f g . Other = g`

Collecting errors

type Errors e = Lift (Constant e) Source

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)`

runErrors :: Errors e a -> Either e a Source

Extractor for computations with accumulating errors.

• `runErrors (pure x) = Right x`
• `runErrors (failure e) = Left e`

failure :: e -> Errors e a Source

Report an error.

eitherToErrors :: Either e a -> Errors e a Source

Convert from `Either` to `Errors` (inverse of `runErrors`).

© The University of Glasgow and others