# functor

## EnglishEdit

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Wikipedia

### NounEdit

functor ‎(plural functors)

1. (grammar) a function word
2. (computing) a function object
3. (category theory) a structure-preserving mapping between categories: if F is a functor from category C to category D, then F maps objects of C to objects of D and morphisms of C to morphisms of D such that any morphism f:XY of C is mapped to a morphism F(f): F(X) → F(Y) of D, such that if $h = g \circ f$ then $F(h) = F(g) \circ F(f)$, and such that identity morphisms (and only identity morphisms) are mapped to identity morphisms. Note: the functor just described is covariant.

## PortugueseEdit

### NounEdit

functor m (plural functores)

1. (category theory) functor (a mapping between categories)