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)

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 Validation

Validate AccValidation

Isomorphisms

isoAccValidationEither :: Iso' (AccValidation e a) (Either e a)

isoValidationEither :: Iso' (Validation e a) (Either e a)

isoAccValidationValidation :: Iso' (AccValidation e a) (Validation e a)