``` sealed class Fix<F> data class MkFix<...

# announcements

[Ifvwm]

sealed class Fix<F>
data class MkFix<F> (val x: F<Fix<F>>): Fix<F>()

this is possible?

[Amirul Zin]

Your data class doesn’t need declare the generic parameter for F and just use it as is. e.g.:

sealed class Fix<F>
data class MkFix<F> (val x: F): Fix<F>()

[Ifvwm]

@Amirul Zin no, it’s a recursive type

[Amirul Zin]

Have you tried my code?

[Ifvwm]

sorry, I can’t access my laptop now

[Amirul Zin]

It’s the same as List<T>.

e.g you can simply have:

List<List<List<List<T>>>>

Since T is generic, so even T itself can be another parametrized generic.

[marstran]

You can do this to constrain the F type to `Fix<F>`:

sealed class Fix<F>
data class MkFix<F : Fix<F>> (val x: F): Fix<F>()

[Ifvwm]

and what values would have this type?

[karelpeeters]

class Foo: Fix<Foo>()

[Ifvwm]

and what it can be used for?

[streetsofboston]

This is not possible. You can't have a type F<A> where F itself is a generic type parameter. Higher kind types are not possible on Kotlin.