It’s not really specific to kotlin. It’s like duck typing, but you basically do something like:

interface A {
    fun foo()
}

class B {
    fun foo() {}
}

class C {
    fun bar() {}
}

val good: A = A::class from B() // Creates a wrapper for A() which implements B
val bad: A = A::class from C() // Throws an exception because the structures don’t match

Basically, it’s a way to not hard code a dependency at compile time.

from

would just be an infix operator which attempts to create a wrapper extending the interface, if the instance could have implemented the interface.