what’s the difference between `interface Stack<T : Any>` and `interface Stack<T>` ? ...

# getting-started

[oday]

what’s the difference between

interface Stack<T : Any>

and

interface Stack<T> ?

T already means literally anything

[Matteo Mirk]

by default T implies T : Any? so includes nullable types. Your first declaration excludes nullable types from the domain.

[oday]

I see, nice ok

[oday]

true, if you go to implement this interface with a class that has type just T, feeding that T back to Stack<T> will complain

[Matteo Mirk]

not sure I understand what you mean, sorry 😕

[oday]

means I tried it, it’s as you said 👍🏻

[Matteo Mirk]

okay good! So the compiler prevents you from declaring a Stack<Int?> if you used the first definition, right?

[oday]

correct