Unfortunately I have not got my attempted implementation to work yet (see bottom of original post). Not sure if I've hit a limitation, bug or what.
As a sometimes-Scala and oftentimes-Python person I too am interested in this topic and specifically the "limitation, bug or what" part.
This is going to silly to the Scala-hardcore but if Arnold's original for loop code and everything like it worked, I'd use a lot more Scala. Python's coroutine like generators are extremely useful in my work (animation and music [1]) and while I know you can do anything you want with lazy collections, the resulting code crosses some kind of threshold for collaboration with people in my field (digital art) or my future self.
best,
Marc.
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