Trying to make generic class with clone method

clone_generic_2.pony

actor Main
  new create(env: Env) =>
    let foo_layers = Layers[Foo] // `Layers` of `Foo`


// The important part is that it defines a clone()
trait MyTrait[U]
  new create()
  fun clone(): U


// One of several classes that will implement MyTrait
class Foo is MyTrait[Foo iso^]
  new create() => None
  fun clone(): Foo iso^ => recover Foo end


// A generic type that holds an Array of the respective MyTrait types, like Foo
class Layers[T: MyTrait[T]]
  var values: Array[T] = Array[T]

  fun clone(): Layers[T] =>
    // The clone we're creating
    let c = recover Layers[T] end

    var i = USize(0)
    let len = values.size()

    // The array for the clone
    let a = recover Array[T](len) end

    // Clone each item in the original array to the new array
    while i < len do
      try
        let item: T = values(i).clone()
        a.push(recover ref item end)
      end
      i = i + 1
    end

    // Put the new array of cloned items on the main clone
    c.values = consume a
    c

Here are the highlights:

• MyTrait defines a clone() that should ultimately return an iso^ copy of whatever is implementing the trait
• Foo is a class that implements MyTrait
• Layers is a generic class that simply wraps an Array of T: MyTrait

The trouble is that I'm trying to give Layers its own clone() method that performs a deep clone. While the clone() is meant to produce an iso, it'll ultimately be placed into the Array as a ref.

Note that the Array in Layers holds T: MyTrait, not simply MyTrait.

What I show above is one of my earlier, simpler attempts, which is clearly wrong. Some guidance would be appreciated.