@hackage / from-sum

Combinators for working with Maybe and Either

Latest0.2.3.0

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  • Last updated , by cdepillabout
  • License BSD-3-Clause

  • Maintained by: cdep.illabout@gmail.com

  • Lottery factor: 0

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Control.FromSum

Build Status Hackage Stackage LTS Stackage Nightly BSD3 license

This Haskell module exports the fromEitherM and fromMaybeM convenience functions.

fromMaybeM :: m a -> Maybe a -> m a

fromEitherM :: (e -> m a) -> Either e a -> m a

fromEitherM leftAction eitherValue is the same as either leftAction pure eitherValue.

fromMaybeM nothingAction maybeValue is the same as maybe nothingAction pure maybeValue.

Usage

>>> import Control.FromSum (fromEitherM, fromMaybeM)
>>> fromMaybeM [] $ Just 5
[5]
>>> fromMaybeM [] Nothing
[]
>>> fromEitherM (\s -> [length s]) $ Right 5
[5]
>>> fromEitherM (\s -> [length s]) $ Left "foo"
[3]