Not OP but maybe those are Bitmapped Vector Tries: https://www.infoq.com/presentations/Functional-Data-Structures-in-Scala/ https://www.infoq.com/presentations/

Not OP but maybe those are Bitmapped Vector Tries: https://www.infoq.com/presentations/Functional-Data-Structures-in-Scala/ https://www.infoq.com/presentations/Functional-Data-Structur...