Functor is a term used in mathematics and computer science to describe a function that maps elements from one category to another. The spelling of the word "functor" is not intuitive, with the second syllable being pronounced as "tər" instead of "tor", as one might expect. The IPA phonetic transcription for the word is /ˈfʌŋktə/, with the stress on the first syllable and the final syllable pronounced as "tə" instead of "tor". Despite its unconventional spelling, "functor" has become a widely used term in these fields.
A functor is a term used in mathematics and computer science to describe an object or structure that can be applied to another object or structure in a systematic way. It acts as a mapping or transformation between two different categories or sets.
In category theory, a functor is a mathematical construct that takes objects and morphisms from one category and relates them to objects and morphisms of another category in a meaningful way, preserving certain structural properties. It maps objects from the source category to objects in the target category, and morphisms (or arrows) from the source category to morphisms in the target category. These mappings should respect the composition of morphisms and preserve the identity morphisms.
In computer science, a functor is a functional programming concept that represents an object or structure that can be transformed or modified by applying a specific function or operation to its elements. It encapsulates the behavior of the function, allowing it to be applied to multiple elements or data structures in a uniform way. Functors are frequently used in functional programming languages to perform operations on collections, such as lists or arrays, by applying a common function to each element. This promotes code reuse, improves readability, and allows for easy modification of the applied function. Overall, functors provide an abstraction mechanism for transforming or manipulating objects or structures in a systematic and consistent way.
The word "functor" has its roots in mathematics and comes from the Latin word "functus", which is the past participle of "fungi" meaning "to perform" or "to carry out". In mathematics, a functor is an object or operation that maps between categories, preserving their structure and relationships. The term was introduced by the mathematician David Hilbert in the early 20th century, and it has since become an important concept in various branches of mathematics, computer science, and logic.