MutableList<Object>

MutableList<in CharSequence>

CharSequence

val

open class Animal{
    private var id:Int = 0
}

data class Cat(
    private var name:String = ""
):Animal()

interface ViewInterface<in T:Animal> {
    fun setAnimal(animal:T)
}

fun main(args:Array<String>){
    
    var x:ViewInterface<Cat> = object:ViewInterface<Cat>{
        override fun setAnimal(s:Cat){
			println("Cat was set")
        } 
    }

    var y:ViewInterface<Animal> = object:ViewInterface<Animal>{
        override fun setAnimal(s:Animal){
			println("Animal was set")
        } 
    }
        
//     x.setAnimal(Animal())
    
    x = y //*This works*
//     y = x //This doesnt
    
//     x.setAnimal(Animal())
    
}

x

ViewInterface<Cat>

ViewInterface

ViewInterface<in Cat>

ViewInterface<Animal>

y = x

y

x

y = x

y

ViewInterface<in Animal>

x