Return the contents of a Left-value or a default value otherwise.
Examples
Basic usage:
fromLeft 1 (Left 3)3fromLeft 1 (Right "foo")1
Modulerelude-1.2.2.2Haskell2010
Relude.Monad.Either
SPDX-License-Identifier : MIT Maintainer : Kowainik xrom.xkov@gmail.com Stability : Stable Portability : Portable
Utilities to work with Either data type.
Contents
Synopsis
- value fromLeft
- value fromRight
- value maybeToLeft
- value maybeToRight
- value leftToMaybe
- value rightToMaybe
- value whenLeft
- value whenLeft_
- value whenLeftM
- value whenLeftM_
- value whenRight
- value whenRight_
- value whenRightM
- value whenRightM_
- Packagerelude-1.2.2.2
- Exports14
- LanguageHaskell2010
- LicenceMIT
- SourceEither.hs
Combinators
Return the contents of a Right-value or a default value otherwise.
Examples
Basic usage:
fromRight 1 (Right 3)3fromRight 1 (Left "foo")1
Monadic combinators
Monadic version of whenLeft.
whenLeftM "bar" (pure $ Left 42) (\a -> "success!" <$ print a)42"success!"
whenLeftM "bar" (pure $ Right 42) (\a -> "success!" <$ print a)"bar"
Monadic version of whenLeft_.
whenLeftM_ (pure $ Right 42) putTextLnwhenLeftM_ (pure $ Left "foo") putTextLnfoo
Applies given action to Either content if Right is given and returns the result. In case of Left the default value will be returned.
whenRight "bar" (Left "foo") (\a -> "success!" <$ print a)"bar"
whenRight "bar" (Right 42) (\a -> "success!" <$ print a)42"success!"
Monadic version of whenRight.
whenRightM "bar" (pure $ Left "foo") (\a -> "success!" <$ print a)"bar"
whenRightM "bar" (pure $ Right 42) (\a -> "success!" <$ print a)42"success!"
Monadic version of whenRight_.
whenRightM_ (pure $ Left "foo") printwhenRightM_ (pure $ Right 42) print42