Data.Validation

Data types similar to Data.Either that are explicit about failure and success.

Data types

data AccValidation err a

A value of the type err or a, however, the Applicative instance accumulates values. This is witnessed by the Semigroup context on the instance. Note that there is no Monad such that ap = (*).

>>> _Success # (+1) <*> _Success # 7 :: AccValidation String Int
AccSuccess 8

>>> _Failure # ["f1"] <*> _Success # 7 :: AccValidation [String] Int
AccFailure ["f1"]

>>> _Success # (+1) <*> _Failure # ["f2"] :: AccValidation [String] Int
AccFailure ["f2"]

>>> _Failure # ["f1"] <*> _Failure # ["f2"] :: AccValidation [String] Int
AccFailure ["f1","f2"]

Constructors

AccFailure err

AccSuccess a

Instances

Bifunctor AccValidation

Bitraversable AccValidation

Bifoldable AccValidation

Swapped AccValidation

Validate AccValidation

Functor (AccValidation err)

Semigroup err => Applicative (AccValidation err)

Foldable (AccValidation err)

Traversable (AccValidation err)

Semigroup err => Alt (AccValidation err)

Semigroup err => Apply (AccValidation err)

(Eq err, Eq a) => Eq (AccValidation err a)

(Data err, Data a) => Data (AccValidation err a)

(Ord err, Ord a) => Ord (AccValidation err a)

(Show err, Show a) => Show (AccValidation err a)

Monoid e => Monoid (AccValidation e a)

((x `mappend` y) `mappend` z) == (x `mappend` (y `mappend` z :: AccValidation [String] Int))

mempty `mappend` x == (x :: AccValidation [String] Int)

x `mappend` mempty == (x :: AccValidation [String] Int)

Semigroup e => Semigroup (AccValidation e a)

((x <> y) <> z) == (x <> (y <> z :: AccValidation [String] Int))

data Validation err a

A value of the type err or a and isomorphic to Data.Either.

>>> _Success # (+1) <*> _Success # 7 :: Validation String Int
Success 8

>>> _Failure # ["f1"] <*> _Success # 7 :: Validation [String] Int
Failure ["f1"]

>>> _Success # (+1) <*> _Failure # ["f2"] :: Validation [String] Int
Failure ["f2"]

>>> _Failure # ["f1"] <*> _Failure # ["f2"] :: Validation [String] Int
Failure ["f1"]

Constructors

Failure err

Success a

Instances

Bifunctor Validation

Bitraversable Validation

Bifoldable Validation

Swapped Validation

Validate Validation

Monad (Validation err)

Functor (Validation err)

Applicative (Validation err)

Foldable (Validation err)

Traversable (Validation err)

Alt (Validation err)

Apply (Validation err)

Bind (Validation err)

(Eq err, Eq a) => Eq (Validation err a)

(Data err, Data a) => Data (Validation err a)

(Ord err, Ord a) => Ord (Validation err a)

(Show err, Show a) => Show (Validation err a)

data ValidationT err m a

The transformer version of Validation.

Constructors

ValidationT

Fields

runValidationT :: m (Validation err a)

Instances

MonadTrans (ValidationT err)

Monad m => Monad (ValidationT err m)

Functor m => Functor (ValidationT err m)

Applicative m => Applicative (ValidationT err m)

Foldable m => Foldable (ValidationT err m)

Traversable m => Traversable (ValidationT err m)

(Functor m, Monad m) => Alt (ValidationT err m)

Apply m => Apply (ValidationT err m)

(Apply m, Monad m) => Bind (ValidationT err m)

data ValidationB m err a

The bifunctor version of ValidationT

Constructors

ValidationB

Fields

runValidationB :: m (Validation err a)

Instances

Functor m => Bifunctor (ValidationB m)

Traversable m => Bitraversable (ValidationB m)

Foldable m => Bifoldable (ValidationB m)

Functor f => Swapped (ValidationB f)

Monad m => Monad (ValidationB m err)

Functor m => Functor (ValidationB m err)

Applicative m => Applicative (ValidationB m err)

Foldable m => Foldable (ValidationB m err)

Traversable m => Traversable (ValidationB m err)

(Functor m, Monad m) => Alt (ValidationB m err)

Apply m => Apply (ValidationB m err)

(Apply m, Monad m) => Bind (ValidationB m err)

type Validation' err a = ValidationT err Identity a

Prisms

_Failure :: Validate f => Prism (f e1 a) (f e2 a) e1 e2

_Success :: Validate f => Prism (f e a) (f e b) a b

Isomorphisms

class Validate f where

Minimal complete definition

Nothing

Methods

_Validation :: Iso (f e a) (f g b) (Validation e a) (Validation g b)

_Validation' :: Iso (f e a) (f g b) (Validation' e a) (Validation' g b)

_AccValidation :: Iso (f e a) (f g b) (AccValidation e a) (AccValidation g b)

_Either :: Iso (f e a) (f g b) (Either e a) (Either g b)

Instances

Validate Either

Validate Validation

Validate AccValidation