data-category-0.7.1: Category theory

LicenseBSD-style (see the file LICENSE)
Maintainersjoerd@w3future.com
Stabilityexperimental
Portabilitynon-portable
Safe HaskellSafe
LanguageHaskell2010

Data.Category.NaturalTransformation

Contents

Description

 
Synopsis

Natural transformations

type (:~>) f g = forall c d. (c ~ Dom f, c ~ Dom g, d ~ Cod f, d ~ Cod g) => Nat c d f g Source #

f :~> g is a natural transformation from functor f to functor g.

type Component f g z = Cod f (f :% z) (g :% z) Source #

A component for an object z is an arrow from F z to G z.

(!) :: (Category c, Category d) => Nat c d f g -> c a b -> d (f :% a) (g :% b) infixl 9 Source #

'n ! a' returns the component for the object a of a natural transformation n. This can be generalized to any arrow (instead of just identity arrows).

o :: (Category c, Category d, Category e) => Nat d e j k -> Nat c d f g -> Nat c e (j :.: f) (k :.: g) Source #

Horizontal composition of natural transformations.

natId :: Functor f => f -> Nat (Dom f) (Cod f) f f Source #

The identity natural transformation of a functor.

srcF :: Nat c d f g -> f Source #

tgtF :: Nat c d f g -> g Source #

Functor category

data Nat :: (* -> * -> *) -> (* -> * -> *) -> * -> * -> * where Source #

Natural transformations are built up of components, one for each object z in the domain category of f and g.

Constructors

Nat :: (Functor f, Functor g, c ~ Dom f, c ~ Dom g, d ~ Cod f, d ~ Cod g) => f -> g -> (forall z. Obj c z -> Component f g z) -> Nat c d f g 
Instances
Category k => CartesianClosed (Presheaves k) Source #

The category of presheaves on a category C is cartesian closed for any C.

Instance details

Defined in Data.Category.CartesianClosed

Associated Types

type Exponential (Presheaves k) y z :: Type Source #

Category d => Category (Nat c d) Source #

Functor category D^C. Objects of D^C are functors from C to D. Arrows of D^C are natural transformations.

Instance details

Defined in Data.Category.NaturalTransformation

Methods

src :: Nat c d a b -> Obj (Nat c d) a Source #

tgt :: Nat c d a b -> Obj (Nat c d) b Source #

(.) :: Nat c d b c0 -> Nat c d a b -> Nat c d a c0 Source #

(Category c, HasBinaryCoproducts d) => HasBinaryCoproducts (Nat c d) Source #

The functor coproduct :+: is the binary coproduct in functor categories.

Instance details

Defined in Data.Category.Limit

Associated Types

type BinaryCoproduct (Nat c d) x y :: Type Source #

Methods

inj1 :: Obj (Nat c d) x -> Obj (Nat c d) y -> Nat c d x (BinaryCoproduct (Nat c d) x y) Source #

inj2 :: Obj (Nat c d) x -> Obj (Nat c d) y -> Nat c d y (BinaryCoproduct (Nat c d) x y) Source #

(|||) :: Nat c d x a -> Nat c d y a -> Nat c d (BinaryCoproduct (Nat c d) x y) a Source #

(+++) :: Nat c d a1 b1 -> Nat c d a2 b2 -> Nat c d (BinaryCoproduct (Nat c d) a1 a2) (BinaryCoproduct (Nat c d) b1 b2) Source #

(Category c, HasBinaryProducts d) => HasBinaryProducts (Nat c d) Source #

The functor product :*: is the binary product in functor categories.

Instance details

Defined in Data.Category.Limit

Associated Types

type BinaryProduct (Nat c d) x y :: Type Source #

Methods

proj1 :: Obj (Nat c d) x -> Obj (Nat c d) y -> Nat c d (BinaryProduct (Nat c d) x y) x Source #

proj2 :: Obj (Nat c d) x -> Obj (Nat c d) y -> Nat c d (BinaryProduct (Nat c d) x y) y Source #

(&&&) :: Nat c d a x -> Nat c d a y -> Nat c d a (BinaryProduct (Nat c d) x y) Source #

(***) :: Nat c d a1 b1 -> Nat c d a2 b2 -> Nat c d (BinaryProduct (Nat c d) a1 a2) (BinaryProduct (Nat c d) b1 b2) Source #

(Category c, HasInitialObject d) => HasInitialObject (Nat c d) Source #

The constant functor to the initial object is itself the initial object in its functor category.

Instance details

Defined in Data.Category.Limit

Associated Types

type InitialObject (Nat c d) :: Type Source #

Methods

initialObject :: Obj (Nat c d) (InitialObject (Nat c d)) Source #

initialize :: Obj (Nat c d) a -> Nat c d (InitialObject (Nat c d)) a Source #

(Category c, HasTerminalObject d) => HasTerminalObject (Nat c d) Source #

The constant functor to the terminal object is itself the terminal object in its functor category.

Instance details

Defined in Data.Category.Limit

Associated Types

type TerminalObject (Nat c d) :: Type Source #

Methods

terminalObject :: Obj (Nat c d) (TerminalObject (Nat c d)) Source #

terminate :: Obj (Nat c d) a -> Nat c d a (TerminalObject (Nat c d)) Source #

type Exponential (Presheaves k) y z Source # 
Instance details

Defined in Data.Category.CartesianClosed

type InitialObject (Nat c d) Source # 
Instance details

Defined in Data.Category.Limit

type InitialObject (Nat c d) = Const c d (InitialObject d)
type TerminalObject (Nat c d) Source # 
Instance details

Defined in Data.Category.Limit

type TerminalObject (Nat c d) = Const c d (TerminalObject d)
type BinaryCoproduct (Nat c d) x y Source # 
Instance details

Defined in Data.Category.Limit

type BinaryCoproduct (Nat c d) x y = x :+: y
type BinaryProduct (Nat c d) x y Source # 
Instance details

Defined in Data.Category.Limit

type BinaryProduct (Nat c d) x y = x :*: y

type Endo k = Nat k k Source #

The category of endofunctors.

type Presheaves k = Nat (Op k) (->) Source #

type Profunctors c d = Nat (Op d :**: c) (->) Source #

Functor isomorphisms

compAssoc :: (Functor f, Functor g, Functor h, Dom f ~ Cod g, Dom g ~ Cod h) => f -> g -> h -> Nat (Dom h) (Cod f) ((f :.: g) :.: h) (f :.: (g :.: h)) Source #

compAssocInv :: (Functor f, Functor g, Functor h, Dom f ~ Cod g, Dom g ~ Cod h) => f -> g -> h -> Nat (Dom h) (Cod f) (f :.: (g :.: h)) ((f :.: g) :.: h) Source #

idPrecomp :: Functor f => f -> Nat (Dom f) (Cod f) (f :.: Id (Dom f)) f Source #

idPrecompInv :: Functor f => f -> Nat (Dom f) (Cod f) f (f :.: Id (Dom f)) Source #

idPostcomp :: Functor f => f -> Nat (Dom f) (Cod f) (Id (Cod f) :.: f) f Source #

idPostcompInv :: Functor f => f -> Nat (Dom f) (Cod f) f (Id (Cod f) :.: f) Source #

constPrecompIn :: Nat j d (f :.: Const j c x) g -> Nat j d (Const j d (f :% x)) g Source #

constPrecompOut :: Nat j d f (g :.: Const j c x) -> Nat j d f (Const j d (g :% x)) Source #

constPostcompIn :: Nat j d (Const k d x :.: f) g -> Nat j d (Const j d x) g Source #

constPostcompOut :: Nat j d f (Const k d x :.: g) -> Nat j d f (Const j d x) Source #

Related functors

data FunctorCompose (c :: * -> * -> *) (d :: * -> * -> *) (e :: * -> * -> *) Source #

Constructors

FunctorCompose 
Instances
Category k => TensorProduct (EndoFunctorCompose k) Source #

Functor composition makes the category of endofunctors monoidal, with the identity functor as unit.

Instance details

Defined in Data.Category.Monoidal

Associated Types

type Unit (EndoFunctorCompose k) :: Type Source #

(Category c, Category d, Category e) => Functor (FunctorCompose c d e) Source #

Composition of functors is a functor.

Instance details

Defined in Data.Category.NaturalTransformation

Associated Types

type Dom (FunctorCompose c d e) :: Type -> Type -> Type Source #

type Cod (FunctorCompose c d e) :: Type -> Type -> Type Source #

type (FunctorCompose c d e) :% a :: Type Source #

Methods

(%) :: FunctorCompose c d e -> Dom (FunctorCompose c d e) a b -> Cod (FunctorCompose c d e) (FunctorCompose c d e :% a) (FunctorCompose c d e :% b) Source #

type Unit (EndoFunctorCompose k) Source # 
Instance details

Defined in Data.Category.Monoidal

type Dom (FunctorCompose c d e) Source # 
Instance details

Defined in Data.Category.NaturalTransformation

type Dom (FunctorCompose c d e) = Nat d e :**: Nat c d
type Cod (FunctorCompose c d e) Source # 
Instance details

Defined in Data.Category.NaturalTransformation

type Cod (FunctorCompose c d e) = Nat c e
type (FunctorCompose c d e) :% (f, g) Source # 
Instance details

Defined in Data.Category.NaturalTransformation

type (FunctorCompose c d e) :% (f, g) = f :.: g

type EndoFunctorCompose k = FunctorCompose k k k Source #

Composition of endofunctors is a functor.

type Precompose f e = FunctorCompose (Dom f) (Cod f) e :.: Tuple2 (Nat (Cod f) e) (Nat (Dom f) (Cod f)) f Source #

Precompose f e is the functor such that Precompose f e :% g = g :.: f, for functors g that compose with f and with codomain e.

type Postcompose f c = FunctorCompose c (Dom f) (Cod f) :.: Tuple1 (Nat (Dom f) (Cod f)) (Nat c (Dom f)) f Source #

Postcompose f c is the functor such that Postcompose f c :% g = f :.: g, for functors g that compose with f and with domain c.

data Wrap f h Source #

Constructors

Wrap f h 
Instances
(Functor f, Functor h) => Functor (Wrap f h) Source #

Wrap f h is the functor such that Wrap f h :% g = f :.: g :.: h, for functors g that compose with f and h.

Instance details

Defined in Data.Category.NaturalTransformation

Associated Types

type Dom (Wrap f h) :: Type -> Type -> Type Source #

type Cod (Wrap f h) :: Type -> Type -> Type Source #

type (Wrap f h) :% a :: Type Source #

Methods

(%) :: Wrap f h -> Dom (Wrap f h) a b -> Cod (Wrap f h) (Wrap f h :% a) (Wrap f h :% b) Source #

type Dom (Wrap f h) Source # 
Instance details

Defined in Data.Category.NaturalTransformation

type Dom (Wrap f h) = Nat (Cod h) (Dom f)
type Cod (Wrap f h) Source # 
Instance details

Defined in Data.Category.NaturalTransformation

type Cod (Wrap f h) = Nat (Dom h) (Cod f)
type (Wrap f h) :% g Source # 
Instance details

Defined in Data.Category.NaturalTransformation

type (Wrap f h) :% g = (f :.: g) :.: h

data Apply (c1 :: * -> * -> *) (c2 :: * -> * -> *) Source #

Constructors

Apply 
Instances
(Category c1, Category c2) => Functor (Apply c1 c2) Source #

Apply is a bifunctor, Apply :% (f, a) applies f to a, i.e. f :% a.

Instance details

Defined in Data.Category.NaturalTransformation

Associated Types

type Dom (Apply c1 c2) :: Type -> Type -> Type Source #

type Cod (Apply c1 c2) :: Type -> Type -> Type Source #

type (Apply c1 c2) :% a :: Type Source #

Methods

(%) :: Apply c1 c2 -> Dom (Apply c1 c2) a b -> Cod (Apply c1 c2) (Apply c1 c2 :% a) (Apply c1 c2 :% b) Source #

type Dom (Apply c1 c2) Source # 
Instance details

Defined in Data.Category.NaturalTransformation

type Dom (Apply c1 c2) = Nat c2 c1 :**: c2
type Cod (Apply c1 c2) Source # 
Instance details

Defined in Data.Category.NaturalTransformation

type Cod (Apply c1 c2) = c1
type (Apply c1 c2) :% (f, a) Source # 
Instance details

Defined in Data.Category.NaturalTransformation

type (Apply c1 c2) :% (f, a) = f :% a

data Tuple (c1 :: * -> * -> *) (c2 :: * -> * -> *) Source #

Constructors

Tuple 
Instances
(Category c1, Category c2) => Functor (Tuple c1 c2) Source #

Tuple converts an object a to the functor Tuple1 a.

Instance details

Defined in Data.Category.NaturalTransformation

Associated Types

type Dom (Tuple c1 c2) :: Type -> Type -> Type Source #

type Cod (Tuple c1 c2) :: Type -> Type -> Type Source #

type (Tuple c1 c2) :% a :: Type Source #

Methods

(%) :: Tuple c1 c2 -> Dom (Tuple c1 c2) a b -> Cod (Tuple c1 c2) (Tuple c1 c2 :% a) (Tuple c1 c2 :% b) Source #

type Dom (Tuple c1 c2) Source # 
Instance details

Defined in Data.Category.NaturalTransformation

type Dom (Tuple c1 c2) = c1
type Cod (Tuple c1 c2) Source # 
Instance details

Defined in Data.Category.NaturalTransformation

type Cod (Tuple c1 c2) = Nat c2 (c1 :**: c2)
type (Tuple c1 c2) :% a Source # 
Instance details

Defined in Data.Category.NaturalTransformation

type (Tuple c1 c2) :% a = Tuple1 c1 c2 a