what is the difference between `interface Foo<T...

# announcements

[liminal]

what is the difference between interface Foo<T : Any> and interface Foo<T>?

[Pablichjenkov]

The first one constraints T to a type in a non nullable subset of Any.
The second one accepts T to be a nullable type in a subset of Any?

[liminal]

Just to clarify, Foo<T> implies that T can be nullable?

[Pablichjenkov]

This is from official docs.
https://kotlinlang.org/docs/reference/generics.html#generic-constraints
The default upper bound (if none specified) is Any?

However, the best way to assure it is testing it on your own.

[Stephan Schroeder]

@liminal yes, Foo<T> is shorhand for Foo<T: Any?>, so T can be a nullable Type (but of course you could restrict that later when implementing Foo StrFoo: Foo<String> wouldn’t be nullable while NStrFoo: Foo<String?> would be)

[liminal]

Thanks guys!