mirror of
https://github.com/idris-lang/Idris2.git
synced 2024-12-17 16:21:46 +03:00
dab2b0d146
If `(~>)` isn't publicly exported, the type checker doesn't know that `Mor` constructs something of type `~>`.
92 lines
2.0 KiB
Idris
92 lines
2.0 KiB
Idris
module Data.Morphisms
|
|
|
|
public export
|
|
record Morphism a b where
|
|
constructor Mor
|
|
applyMor : a -> b
|
|
|
|
infixr 1 ~>
|
|
|
|
public export
|
|
(~>) : Type -> Type -> Type
|
|
(~>) = Morphism
|
|
|
|
public export
|
|
record Endomorphism a where
|
|
constructor Endo
|
|
applyEndo : a -> a
|
|
|
|
public export
|
|
record Kleislimorphism (f : Type -> Type) a b where
|
|
constructor Kleisli
|
|
applyKleisli : a -> f b
|
|
|
|
export
|
|
Functor (Morphism r) where
|
|
map f (Mor a) = Mor $ f . a
|
|
|
|
export
|
|
Applicative (Morphism r) where
|
|
pure a = Mor $ const a
|
|
(Mor f) <*> (Mor a) = Mor $ \r => f r $ a r
|
|
|
|
export
|
|
Monad (Morphism r) where
|
|
(Mor h) >>= f = Mor $ \r => applyMor (f $ h r) r
|
|
|
|
export
|
|
Semigroup a => Semigroup (Morphism r a) where
|
|
f <+> g = Mor $ \r => (applyMor f) r <+> (applyMor g) r
|
|
|
|
export
|
|
Monoid a => Monoid (Morphism r a) where
|
|
neutral = Mor \r => neutral
|
|
|
|
export
|
|
Semigroup (Endomorphism a) where
|
|
(Endo f) <+> (Endo g) = Endo $ g . f
|
|
|
|
export
|
|
Monoid (Endomorphism a) where
|
|
neutral = Endo id
|
|
|
|
export
|
|
Functor f => Functor (Kleislimorphism f a) where
|
|
map f (Kleisli g) = Kleisli (map f . g)
|
|
|
|
export
|
|
Applicative f => Applicative (Kleislimorphism f a) where
|
|
pure a = Kleisli $ const $ pure a
|
|
(Kleisli f) <*> (Kleisli a) = Kleisli $ \r => f r <*> a r
|
|
|
|
export
|
|
Monad f => Monad (Kleislimorphism f a) where
|
|
(Kleisli f) >>= g = Kleisli $ \r => do
|
|
k1 <- f r
|
|
applyKleisli (g k1) r
|
|
|
|
-- Applicative is a bit too strong, but there is no suitable superclass
|
|
export
|
|
(Semigroup a, Applicative f) => Semigroup (Kleislimorphism f r a) where
|
|
f <+> g = Kleisli \r => (<+>) <$> (applyKleisli f) r <*> (applyKleisli g) r
|
|
|
|
export
|
|
(Monoid a, Applicative f) => Monoid (Kleislimorphism f r a) where
|
|
neutral = Kleisli \r => pure neutral
|
|
|
|
export
|
|
Cast (Endomorphism a) (Morphism a a) where
|
|
cast (Endo f) = Mor f
|
|
|
|
export
|
|
Cast (Morphism a a) (Endomorphism a) where
|
|
cast (Mor f) = Endo f
|
|
|
|
export
|
|
Cast (Morphism a (f b)) (Kleislimorphism f a b) where
|
|
cast (Mor f) = Kleisli f
|
|
|
|
export
|
|
Cast (Kleislimorphism f a b) (Morphism a (f b)) where
|
|
cast (Kleisli f) = Mor f
|