GHC 10.0.0.20260917 · lts/ghc-10.0.x · 8fef28d · 2026-11-02
Modulevalidation-selective-0.2.0.0Haskell2010
SPDX-License-Identifier: MPL-2.0 Maintainer: Kowainik xrom.xkov@gmail.com Stability: Stable Portability: Portable
Helpful combinators to work with Validation data type.
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])
Applies the given action to Validation if it is Success and returns the result. In case of Failure the default value is returned.
whenSuccess "bar" (Failure "foo") (\a -> "success!" <$ print a)"bar"
whenSuccess "bar" (Success 42) (\a -> "success!" <$ print a)42"success!"
Applies the given action to Validation if it is Failure and returns the result. In case of Success the default value is returned.
whenFailure "bar" (Failure 42) (\a -> "foo" <$ print a)42"foo"
whenFailure "bar" (Success 42) (\a -> "foo" <$ print a)"bar"
Applies given action to the Validation content if it is Success.
Similar to whenSuccess but the default value is ().
whenSuccess_ (Failure "foo") printwhenSuccess_ (Success 42) print42
Applies given action to the Validation content if it is Failure.
Similar to whenFailure but the default value is ().
whenFailure_ (Success 42) putStrLnwhenFailure_ (Failure "foo") putStrLnfoo
Monadic version of whenSuccess. Applies monadic action to the given Validation in case of Success. Returns the resulting value, or provided default.
whenSuccessM "bar" (pure $ Failure "foo") (\a -> "success!" <$ print a)"bar"
whenSuccessM "bar" (pure $ Success 42) (\a -> "success!" <$ print a)42"success!"
Monadic version of whenFailure. Applies monadic action to the given Validation in case of Failure. Returns the resulting value, or provided default.
whenFailureM "bar" (pure $ Failure 42) (\a -> "foo" <$ print a)42"foo"
whenFailureM "bar" (pure $ Success 42) (\a -> "foo" <$ print a)"bar"
Monadic version of whenSuccess_.
Applies monadic action to the given Validation in case of Success.
Similar to whenSuccessM but the default is ().
whenSuccessM_ (pure $ Failure "foo") printwhenSuccessM_ (pure $ Success 42) print42
Monadic version of whenFailure_.
Applies monadic action to the given Validation in case of Failure.
Similar to whenFailureM but the default is ().
whenFailureM_ (pure $ Success 42) putStrLnwhenFailureM_ (pure $ Failure "foo") putStrLnfoo
Maps Failure of Validation to Just.
failureToMaybe (Failure True)Just TruefailureToMaybe (Success "aba")Nothing
Maps Success of Validation to Just.
successToMaybe (Failure True)NothingsuccessToMaybe (Success "aba")Just "aba"