functor definition by American Heritage Dictionary
The American Heritage® Dictionary of the English Language, 4th edition Copyright © 2010 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
- One that performs an operation or a function.
- Grammar See function word.
Origin of functorNew Latin fūnctor, from Latin fūnctiō, performance, function; see function.
functor definition by Wiktionary
- (grammar) a function word
- (computing) a function object
- (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:X→Y of C is mapped to a morphism F(f): F(X) → F(Y) of D, such that if then , and such that identity morphisms (only identity morphisms) are mapped to identity morphisms. Note: the functor just described is covariant.