Are you an EPFL student looking for a semester project?
Work with us on data science and visualisation projects, and deploy your project as an app on top of Graph Search.
Concept
Unit type
Summary
In the area of mathematical logic and computer science known as type theory, a unit type is a type that allows only one value (and thus can hold no information). The carrier (underlying set) associated with a unit type can be any singleton set. There is an isomorphism between any two such sets, so it is customary to talk about the unit type and ignore the details of its value. One may also regard the unit type as the type of 0-tuples, i.e. the of no types.
The unit type is the terminal object in the of types and typed functions. It should not be confused with the zero or bottom type, which allows no values and is the initial object in this category. Similarly, the Boolean is the type with two values.
The unit type is implemented in most functional programming languages. The void type that is used in some imperative programming languages serves some of its functions, but because its carrier set is empty, it has some limitations (as detailed below).
Several computer programming languages provide a unit type to specify the result type of a function with the sole purpose of causing a side effect, and the argument type of a function that does not require arguments.
In Haskell, Rust, and Elm, the unit type is called () and its only value is also (), reflecting the 0-tuple interpretation.
In ML descendants (including OCaml, Standard ML, and F#), the type is called unit but the value is written as ().
In Scala, the unit type is called Unit and its only value is written as ().
In Common Lisp the type named is a unit type which has one value, namely the symbol . This should not be confused with the type, which is the bottom type.
In Python, there is a type called NoneType which allows the single value of None.
In Swift, the unit type is called Void or () and its only value is also (), reflecting the 0-tuple interpretation.
In Java, the unit type is called Void and its only value is null.
In Go, the unit type is written struct{} and its value is struct{}{}.
In PHP, the unit type is called null, which only value is NULL itself.
Official source
About this result
This page is automatically generated and may contain information that is not correct, complete, up-to-date, or relevant to your search query. The same applies to every other page on this website. Please make sure to verify the information with EPFL's official sources.
Ontological neighbourhood
Related courses (3)
CS-108: Practice of object-oriented programming
Les étudiants perfectionnent leurs connaissances en Java et les mettent en pratique en réalisant un projet de taille conséquente. Ils apprennent à utiliser et à mettre en œuvre les principaux types de
MATH-661: Advanced Scientific Programming in Python
This seminar teaches the participants to use advanced Python concepts for writing easier to read, more flexible and faster code.
It teaches concepts in a hands-on and tangible fashion, providing examp
CS-107: Introduction to programming
Ce cours aborde les concepts fondamentaux de la programmation et de la programmation orientée objet (langage JAVA). Il permet également de se familisarier avec un environnement de développement inform