Definitions
from The American Heritage® Dictionary of the English Language, 5th Edition.
 noun One that performs an operation or a function.
from Wiktionary, Creative Commons Attribution/ShareAlike License.
 noun grammar a
function word  noun computing a
function object  noun mathematics a structurepreserving
mapping betweencategories : 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 (and only identity morphisms) are mapped to identity morphisms. Note: the functor just described iscovariant .
Etymologies
from The American Heritage® Dictionary of the English Language, 4th Edition
Support
Help support Wordnik (and make this page adfree) by adopting the word functor.
Examples

In the regimented environment of LeÅniewski's logical languages this always takes place in the following way: a combining expression, which we may call a functor, precedes a left parenthesis of some kind, which is then followed by a sequence of one or more argument expressions, followed by a right parenthesis symmetric to the other one, which terminates the complex.

Strict memoization (really hyperstrict) is centered on a family of trie functors, defined as a functor

"functor" we need to be clear whether we're talking about one of these objects (ie a functor in the underlying category), or about a functor over this category.

Moreover, in GEM the generalized Product principle (P. 16Ï) is also derivable as a theorem, with ˜Ï™ as weak as the requirement of mutual overlap, and we can introduce a corresponding functor as follows:

I am pretty sure that violates one of the applicative functor laws. (f pure x = pure ($x) f).

For example, “is” has s/nn as its categorial index; it says that” is “is a twoplaced functor of two nominal arguments which forms a sentence.

I am pretty sure that violates one of the applicative functor laws. (f pure x = pure ($x) f).

So quantum mechanics and general relativity at least within this “partial functor” are equivalent, and might ultimately prove to be two aspects of an identical system.
If We Live in a Multiverse, How Many Are There?  Universe Today

Since quotations are functor expressions without internal structure, (BQ2) is explained: there's no possibility for quantifying into a quotation on this view.

Coarsegraining might be represented as a functor, or something like that, establishing some kind of equivalence which lets you have a weaker notion of isomorphism.
Comments
Log in or sign up to get involved in the conversation. It's quick and easy.