shithub: MicroHs

ref: df6464ed444920bfbcbf22582547c562bebec026
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)