Modulevalidation-selective-0.2.0.0Haskell2010

Validation.Combinators

SPDX-License-Identifier: MPL-2.0 Maintainer: Kowainik xrom.xkov@gmail.com Stability: Stable Portability: Portable

Helpful combinators to work with Validation data type.

13 values

Packagevalidation-selective-0.2.0.0
Exports13
LanguageHaskell2010
LicenceMPL-2.0
SourceCombinators.hs

valuevalidateAll

:: (Foldable f, Semigroup e)
=> f (a -> Validation e b)
-> a
-> Validation e a

Validate all given checks in a Foldable. Returns the Success of the start element when all checks are successful.

A basic example of usage could look like this:

> let validatePassword = validateAll
        [ validateEmptyPassword
        , validateShortPassword
        ]

> validateAll "VeryStrongPassword"
Success "VeryStrongPassword"

> validateAll ""
Failure (EmptyPassword :| [ShortPassword])

When* functions

8 declarations

valuewhenSuccess :: Applicative f => x -> Validation e a -> (a -> f x) -> f x

Applies the given action to Validation if it is Success and returns the result. In case of Failure the default value is returned.

Example1 expression

>>> whenSuccess "bar" (Failure "foo") (\a -> "success!" <$ print a)"bar"

Example1 expression

>>> whenSuccess "bar" (Success 42) (\a -> "success!" <$ print a)42"success!"

valuewhenFailure :: Applicative f => x -> Validation e a -> (e -> f x) -> f x

Applies the given action to Validation if it is Failure and returns the result. In case of Success the default value is returned.

Example1 expression

>>> whenFailure "bar" (Failure 42) (\a -> "foo" <$ print a)42"foo"

Example1 expression

>>> whenFailure "bar" (Success 42) (\a -> "foo" <$ print a)"bar"

valuewhenSuccess_ :: Applicative f => Validation e a -> (a -> f ()) -> f ()

Applies given action to the Validation content if it is Success.

Similar to whenSuccess but the default value is ().

Example2 expressions

>>> whenSuccess_ (Failure "foo") print>>> whenSuccess_ (Success 42) print42

valuewhenFailure_ :: Applicative f => Validation e a -> (e -> f ()) -> f ()

Applies given action to the Validation content if it is Failure.

Similar to whenFailure but the default value is ().

Example2 expressions

>>> whenFailure_ (Success 42) putStrLn>>> whenFailure_ (Failure "foo") putStrLnfoo

valuewhenSuccessM :: Monad m => x -> m (Validation e a) -> (a -> m x) -> m x

Monadic version of whenSuccess. Applies monadic action to the given Validation in case of Success. Returns the resulting value, or provided default.

Example1 expression

>>> whenSuccessM "bar" (pure $ Failure "foo") (\a -> "success!" <$ print a)"bar"

Example1 expression

>>> whenSuccessM "bar" (pure $ Success 42) (\a -> "success!" <$ print a)42"success!"

valuewhenFailureM :: Monad m => x -> m (Validation e a) -> (e -> m x) -> m x

Monadic version of whenFailure. Applies monadic action to the given Validation in case of Failure. Returns the resulting value, or provided default.

Example1 expression

>>> whenFailureM "bar" (pure $ Failure 42) (\a -> "foo" <$ print a)42"foo"

Example1 expression

>>> whenFailureM "bar" (pure $ Success 42) (\a -> "foo" <$ print a)"bar"

valuewhenSuccessM_ :: Monad m => m (Validation e a) -> (a -> m ()) -> m ()

Monadic version of whenSuccess_. Applies monadic action to the given Validation in case of Success. Similar to whenSuccessM but the default is ().

Example2 expressions

>>> whenSuccessM_ (pure $ Failure "foo") print>>> whenSuccessM_ (pure $ Success 42) print42

valuewhenFailureM_ :: Monad m => m (Validation e a) -> (e -> m ()) -> m ()

Monadic version of whenFailure_. Applies monadic action to the given Validation in case of Failure. Similar to whenFailureM but the default is ().

Example2 expressions

>>> whenFailureM_ (pure $ Success 42) putStrLn>>> whenFailureM_ (pure $ Failure "foo") putStrLnfoo

Maybe conversion

4 declarations

valuefailureToMaybe :: Validation e a -> Maybe e

Maps Failure of Validation to Just.

Example2 expressions

>>> failureToMaybe (Failure True)Just True>>> failureToMaybe (Success "aba")Nothing

valuesuccessToMaybe :: Validation e a -> Maybe a

Maps Success of Validation to Just.

Example2 expressions

>>> successToMaybe (Failure True)Nothing>>> successToMaybe (Success "aba")Just "aba"

valuemaybeToFailure :: a -> Maybe e -> Validation e a

Maps Just to Failure In case of Nothing it wraps the given default value into Success.

Example2 expressions

>>> maybeToFailure True (Just "aba")Failure "aba">>> maybeToFailure True NothingSuccess True

valuemaybeToSuccess :: e -> Maybe a -> Validation e a

Maps Just to Success. In case of Nothing it wraps the given default value into Failure

Example2 expressions

>>> maybeToSuccess True (Just "aba")Success "aba">>> maybeToSuccess True NothingFailure True