both

Like Maybe, but with a different Monoid instance. https://github.com/barrucadu/both

Version on this page:0.1.1.0
LTS Haskell 8.15:0.1.1.0
Stackage Nightly 2017-05-26:0.1.1.0
Latest on Hackage:0.1.1.0
MIT licensed by Michael Walker
Maintained by mike@barrucadu.co.uk

Module documentation for 0.1.1.0

The Monoid instance for Maybe behaves like so:

instance Monoid a => Monoid (Maybe a) where
  mappend (Just x) (Just y) = Just $ x <> y
  mappend (Just x) Nothing  = Just x
  mappend Nothing  (Just y) = Just y
  mappend Nothing  Nothing  = Nothing

  mempty = Nothing

Both is a newtype wrapper around Maybe providing this instance:

instance Monoid a => Monoid (Both a) where
  mappend (Just x) (Just y) = Just $ x <> y
  mappend _ _ = Nothing

  mempty = Just mempty
Depends on:
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