# Any news on nested typealiases?

**URL:** <https://discuss.kotlinlang.org/t/any-news-on-nested-typealiases/18743>\
**Category:** Language Design\
**Created:** [August 11, 2020, 5:57pm UTC](https://discuss.kotlinlang.org/t/any-news-on-nested-typealiases/18743 "2020-08-11T17:57:34Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![rnikander](https://sea1.discourse-cdn.com/flex019/user_avatar/discuss.kotlinlang.org/rnikander/32/6881_2.png) [@rnikander](https://discuss.kotlinlang.org/u/rnikander)\
**Post date:** [August 11, 2020, 5:57pm UTC](https://discuss.kotlinlang.org/t/any-news-on-nested-typealiases/18743/1 "2020-08-11T17:57:34Z")

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These work in Swift without much problem but apparently aren’t allowed in Kotlin. I guess years ago there was some problem with implementing them. Has anything changed?

They seem useful for simplifying and not repeating long-winded generic or function types inside a class/object implementation.

```
class Foo<T> {
    typealias Formatter = (Int, String) -> String
    typealias MyMap = HashMap<String, List<T>>
    ...

```