Commit e34e30e4 authored by Andrew Martin's avatar Andrew Martin Committed by Ben Gamari
Browse files

Warn against using Data.Monoid.First

Noting that it will be removed in the future.
parent 358b5080
......@@ -88,6 +88,16 @@ import Data.Semigroup.Internal
--
-- >>> getFirst (First (Just "hello") <> First Nothing <> First (Just "world"))
-- Just "hello"
--
-- Use of this type is discouraged. Note the following equivalence:
--
-- > Data.Monoid.First x === Maybe (Data.Semigroup.First x)
--
-- In additional to being equivalent in the structural sense, the two
-- also have 'Monoid' instances that behave the same. This type will
-- be marked deprecated in GHC 8.8. It will be removed in GHC 8.10.
-- Users are advised to use the variant from "Data.Semigroup" and wrap
-- it in 'Maybe'.
newtype First a = First { getFirst :: Maybe a }
deriving ( Eq -- ^ @since 2.01
, Ord -- ^ @since 2.01
......
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