# Type Parameter Constraint

DevFeed: [Type Parameter Constraint](<https://devfeed.tech/articles/type-parameter-constraint-25025.md>)

Original publisher: [Read original article](<https://typealias.com/concepts/type-parameter-constraint/>)

Author: author@typealias.com (Dave Leeds)

Published: 2017-09-30T01:54:04Z

Content type: tutorial

Language: en

Sources: [Dave Leeds on Kotlin - typealias.com](<https://devfeed.tech/sources/dave-leeds-on-kotlin-typealias-com.md>)

Topics: [Kotlin](<https://devfeed.tech/topics/kotlin.md>), [Code](<https://devfeed.tech/topics/code.md>)

Tags: [article](<https://devfeed.tech/tags/article.md>), [classes](<https://devfeed.tech/tags/classes.md>), [examples](<https://devfeed.tech/tags/examples.md>), [function](<https://devfeed.tech/tags/function.md>), [generic](<https://devfeed.tech/tags/generic.md>), [interface](<https://devfeed.tech/tags/interface.md>), [kotlin](<https://devfeed.tech/tags/kotlin.md>), [programming](<https://devfeed.tech/tags/programming.md>), [property](<https://devfeed.tech/tags/property.md>), [syntax](<https://devfeed.tech/tags/syntax.md>), [type-parameter](<https://devfeed.tech/tags/type-parameter.md>), [type-parameters](<https://devfeed.tech/tags/type-parameters.md>), [types](<https://devfeed.tech/tags/types.md>), [variance](<https://devfeed.tech/tags/variance.md>)

## AI overview

This Kotlin article explains type parameter constraints: how upper bounds restrict accepted type arguments while preserving type information, how to apply constraints to interfaces, classes, functions, and extension properties, and how to express single or multiple constraints using concise and verbose syntax.

## Source excerpt

Overview Type parameter constraints allow you to limit the types that can be accepted as a type argument to an upper bound, giving you the ability to invoke functions and properties on an object while preserving the type. If that sounds confusing, go check out the guide, When to Use Type Parameter Constraints, which walks through the use cases in more detail. In this article, we're going to look at the variety of ways that you can create a type parameter constraint in Kotlin.