shithub: MicroHs

ref: f63867c6adcb110682f7b5b3ff180c6a5280e53e
dir: /lib/Data/Functor/Const.hs/

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-- Copyright 2023 Lennart Augustsson
-- See LICENSE file for full license.
module Data.Functor.Const(Const(..), getConst) where
import Primitives
import Control.Applicative
import Control.Monad
import Data.Bool
import Data.Eq
import Data.Function
import Data.Functor
import Data.Int
import Data.Monoid
import Data.Ord
import Text.Show

type Const :: forall k . Type -> k -> Type
newtype Const a b = Const a
  deriving (Eq, Ord, Show)

getConst :: forall a b . Const a b -> a
getConst (Const a) = a

instance forall a . Functor (Const a) where
  fmap _ (Const a) = Const a

instance forall m . Monoid m => Applicative (Const m) where
  pure _ = Const mempty
  Const a <*> Const b = Const (a `mappend` b)