I see... I thought about wrapping the iterator in a closure, but that won't help. It would work if yeild was called from the closure's block (not from a reusable helper function).

My example means that my loop is calling next_inorder() to loop. It does not wait for next_inorder() to return undef, but breaks out of the loop when it sees the element it's looking for. next_inorder yields. Caller want's to quit early. Get it?

—John