[fuhngk-ter] 
| 1. | that which functions. |
| 2. | Linguistics. a function word or affix. |
| function word n. A word, such as a preposition, a conjunction, or an article, that has little semantic content of its own and chiefly indicates a grammatical relationship. Also called form word, functor. |
| func·tor (fŭngk'tər) n.
[New Latin, from Latin fūnctiō, performance, function; see function.] |
functor
In category theory, a functor F is an operator on types. F is also considered to be a polymorphic operator on functions with the type
F : (a -> b) -> (F a -> F b).
Functors are a generalisation of the function "map". The type operator in this case takes a type T and returns type "list of T". The map function takes a function and applies it to each element of a list.
(1995-02-07)
tər