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Add Semiring instance #59

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Merged
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Nov 10, 2021
Merged

Add Semiring instance #59

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efa00f3
Add Semiring instance
ozkutuk Nov 6, 2021
8415e27
Update CHANGELOG.md
ozkutuk Nov 6, 2021
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1 change: 1 addition & 0 deletions CHANGELOG.md
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Expand Up @@ -7,6 +7,7 @@ Notable changes to this project are documented in this file. The format is based
Breaking changes:

New features:
- Added `Semiring` instance (#59)

Bugfixes:

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10 changes: 10 additions & 0 deletions src/Data/Maybe.purs
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Expand Up @@ -190,6 +190,16 @@ instance semigroupMaybe :: Semigroup a => Semigroup (Maybe a) where
instance monoidMaybe :: Semigroup a => Monoid (Maybe a) where
mempty = Nothing

instance semiringMaybe :: Semiring a => Semiring (Maybe a) where
zero = Nothing
one = Just one

add Nothing y = y
add x Nothing = x
add (Just x) (Just y) = Just (add x y)

mul x y = mul <$> x <*> y

-- | The `Eq` instance allows `Maybe` values to be checked for equality with
-- | `==` and inequality with `/=` whenever there is an `Eq` instance for the
-- | type the `Maybe` contains.
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