Algebraic data type
in computer programming, a type formed by combining other types
In computer programming, especially in functional programming and type theory, an algebraic data type (ADT) is a composite data type, i.e. a type formed by combining other types.
An algebraic data type is defined by two key constructions: a sum and a product. These are sometimes referred to as "OR" and "AND" types.
A sum type is a choice between possibilities. The value of a sum type can match one of several defined variants. For example, a type representing the state of a traffic light could be either Red, Amber, or Green. A shape type could be either a Circle (which stores a radius) or a Square (which stores a width). In formal terms, these variants are known as tagged unions or disjoint unions. Each variant has a name, called a constructor, which can also carry data.
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This entry incorporates text from “Algebraic data type” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.