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"]

Instances

Typeable2 AccValidation

Bitraversable AccValidation

Bifunctor AccValidation

Bifoldable AccValidation

Swapped AccValidation

Validate AccValidation

Functor (AccValidation err)

Semigroup err => Applicative (AccValidation err)

Foldable (AccValidation err)

Traversable (AccValidation err)

(Semigroup err, Monoid err) => Alternative (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"]

Instances

Typeable2 Validation

Bitraversable Validation

Bifunctor Validation

Bifoldable Validation

Swapped Validation

Validate Validation

Monad (Validation err)

Functor (Validation err)

Applicative (Validation err)

Foldable (Validation err)

Traversable (Validation err)

Monoid err => Alternative (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 m err a

The transformer version of Validation.

Constructors

ValidationT

Fields

runValidationT :: m (Validation err a)

Instances

Traversable m => Bitraversable (ValidationT m)

Functor m => Bifunctor (ValidationT m)

Foldable m => Bifoldable (ValidationT m)

Functor f => Swapped (ValidationT f)

Monad m => Monad (ValidationT m err)

Functor m => Functor (ValidationT m err)

Applicative m => Applicative (ValidationT m err)

Foldable m => Foldable (ValidationT m err)

Traversable m => Traversable (ValidationT m err)

(Applicative m, Monad m, Monoid err) => Alternative (ValidationT m err)

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

Apply m => Apply (ValidationT m err)

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

type Validation' err a = ValidationT Identity err a

Prisms

class Validate f where

Methods

_Failure :: Prism (f e1 a) (f e2 a) e1 e2

_Success :: Prism (f e a) (f e b) a b

Instances

Validate Either

Validate Validation

Validate AccValidation

Isomorphisms

isoAccValidationEither :: Iso (AccValidation e a) (AccValidation f b) (Either e a) (Either f b)

isoValidationEither :: Iso (Validation e a) (Validation f b) (Either e a) (Either f b)

isoAccValidationValidation :: Iso (AccValidation e a) (AccValidation f b) (Validation e a) (Validation f b)

isoValidationTEither :: Iso (Validation' e a) (Validation' f b) (Either e a) (Either f b)

isoAccValidationValidationT :: Iso (AccValidation e a) (AccValidation f b) (Validation' e a) (Validation' f b)

isoValidationValidationT :: Iso (Validation e a) (Validation f b) (Validation' e a) (Validation' f b)