a type of mapping between categories

A functor is a type of mapping between categories, which is applied in category theory.

category theory

The word 'functor' comes from category theory, which is a very general, very abstract branch of mathematics.

a design pattern inspired by the definition from category theory that allows one to apply a function to values inside a generic type without changing the structure of the generic type

In functional programming, a functor is a design pattern inspired by the definition from category theory that allows one to apply a function to values inside a generic type without changing the structure of the generic type.

a function that can be manipulated as an object, or an object representing a single, generic function

Functor - A functor is a function that can be manipulated as an object, or an object representing a single, generic function.

a class or struct which acts like a function

A functor is a class or struct which acts like a function.

In mathematics

A functor, in mathematics, is a map between categories.

a design pattern , inspired by the definition from category theorythat allows for a generic type to apply a function inside without changing the structure of the generic type

In functional programming, a functor is a design pattern inspired by the definition from category theory, that allows for a generic type to apply a function inside without changing the structure of the generic type.

In Functional Programming

In functional programming, a functor is a design pattern inspired by the definition from category theory, that allows for a generic type to apply a function inside without changing the structure of the generic type.

a concept from category theory that can be applied to programming

A Functor is a concept from category theory that can be applied to programming.

an object that behaves like a function

A functor is an object that behaves like a function.

given a value and a function

A functor is a function, given a value and a function, does the right thing.

just a data type which can be mapped over

A functor is just a data type which can be mapped over, i.e. just a data type provides a `map` method.

a morphism between categories, A -

A functor is a morphism between categories, A -

typeclass

The Functor is the most fundamental typeclass in the standard libraries.

an operation on spaces and functions between the Jacobians

A functor is an operation on spaces and functions between the Jacobians .

a collection of sets and functions

Given any small category , a functor is a collection of sets and functions .

a special kind of function on an algebra

A functor, in the mathematical sense, is a special kind of function on an algebra.

a convenient and general way of organizing a signature

For both algebra and coalgebra, a functor is a convenient and general way of organizing a signature.

way to apply function over a structure we don’t want to alter

Functor is a way to apply function over a structure we don’t want to alter.

that implements a mapping function with the purpose of lifting values into a container

A functor is nothing more than a type that implements a mapping function with the purpose of lifting values into a container.