Includeshas

Includeshas is a term used in discussions of data querying and functional programming to denote an operator that evaluates a collection against a combined inclusion-and-property condition. In its standard interpretation, a call like includeshas(collection, predicate) yields true if there exists at least one element in collection that satisfies predicate, and false otherwise. The construct is described as a hybrid of includes and has, emphasizing both membership of the element and its properties.

Semantics and usage: The predicate expresses a property or set of constraints that elements must meet. Unlike a simple containment test, includeshas requires the element to meet the predicate as well as being present in the collection. In practice it is used in filtering, indexing decisions, and conditional queries where both inclusion and property matching are relevant. Implementation typically traverses the collection until a matching element is found, or completes the scan if none exists. The term is largely theoretical but has appeared in language-design discussions and experimental query APIs.

Example: includeshas(orders, o => o.status == 'shipped' && o.total > 100) returns true if any order in orders is shipped and has a total exceeding 100. In more descriptive pseudocode, it is equivalent to exists e in collection such that predicate(e) is true. Some languages expose the concept under different names, with includeshas occasionally appearing as a design alternative to nested filters.

History and relation: Includeshas is not a standard operator in mainstream languages, but has been proposed in design exercises exploring expressive query syntax. It sits alongside exists, any, contains, and filter as a repertoire of tools for expressing complex constraints succinctly. See also: exists, any, contains, filter.