Documentation

Mathlib.CategoryTheory.Functor.Hom

The hom functor #

The hom functor, sending (X, Y) to the type X ⟶ Y.

source
def CategoryTheory.Functor.hom (C : Type u) [Category.{v, u} C] :
Functor (Cᵒᵖ × C) (Type v)

Functor.hom is the hom-pairing, sending (X, Y) to X ⟶ Y, contravariant in X and covariant in Y.

Instances For
    source
    @[simp]
    theorem CategoryTheory.Functor.hom_obj (C : Type u) [Category.{v, u} C] (p : Cᵒᵖ × C) :
    (hom C).obj p = (Opposite.unop p.1 ⟶ p.2)
    source
    @[simp]
    theorem CategoryTheory.Functor.hom_map (C : Type u) [Category.{v, u} C] {X✝ Y✝ : Cᵒᵖ × C} (f : X✝ ⟶ Y✝) :
    (hom C).map f = TypeCat.ofHom fun (h : Opposite.unop X✝.1 ⟶ X✝.2) => CategoryStruct.comp f.1.unop (CategoryStruct.comp h f.2)