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Type variance

In computer programming, type variance is the relationship between subtypes of a composite type (e.g. List) and the subtypes of its components (e.g. Int). A language's chosen variance determines the relationship between, for example, a list of Cats and a list of Animals, or a function returning Cat and a function returning Animal.

Inheritance in object-oriented languages, Overview & Generic types

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Overview

Etymology

Formal definition

Arrays

Function types

Inheritance in object-oriented languages

Generic types

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Map overview Semantic statistics

Type variance

Nodes73
Edges72
Triples4
Avg. degree1.97
Density0.027397
Components1

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Type variance

Top relations

is a · 1
Type variance → relationship between subtypes of a composite type

Important terminology Word statistics

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Important terminology

type covariant types variance method java example contravariant parameter function language methods one annotations parameters array subtype languages cat invariant

Entity relationships Subject–Predicate–Object triples

SubjectPredicateObjectConfidenceSrc
Type varianceis arelationship between subtypes of a composite type0.90text
arraysinstance ofthe subtyping relation of the simple types is reversed for the complex types.A programming language designer will consider variance when devising typing rules for language features0.80text
inheritanceinstance ofthe subtyping relation of the simple types is reversed for the complex types.A programming language designer will consider variance when devising typing rules for language features0.80text
and generic datatypesinstance ofthe subtyping relation of the simple types is reversed for the complex types.A programming language designer will consider variance when devising typing rules for language features0.80text

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