Idris2/libs/base/Control/Monad/Identity.idr
2020-05-18 14:00:08 +01:00

46 lines
927 B
Idris

module Control.Monad.Identity
public export
record Identity (a : Type) where
constructor Id
runIdentity : a
public export
Functor Identity where
map fn (Id a) = Id (fn a)
public export
Applicative Identity where
pure x = Id x
(Id f) <*> (Id g) = Id (f g)
public export
Monad Identity where
(Id x) >>= k = k x
public export
Show a => Show (Identity a) where
showPrec d (Id x) = showCon d "Id" $ showArg x
public export
Eq a => Eq (Identity a) where
(Id x) == (Id y) = x == y
public export
Ord a => Ord (Identity a) where
compare (Id x) (Id y) = compare x y
-- public export
-- Enum a => Enum (Identity a) where
-- toNat (Id x) = toNat x
-- fromNat n = Id $ fromNat n
-- pred (Id n) = Id $ pred n
public export
(Semigroup a) => Semigroup (Identity a) where
(<+>) x y = Id (runIdentity x <+> runIdentity y)
public export
(Monoid a) => Monoid (Identity a) where
neutral = Id (neutral)