unfoldl is:exact

unfoldl f x is equivalent to reverse (unfoldr (fmap swap . f) x).

unfoldl f x is equivalent to reverse (unfoldr (fmap swap . f) x).

Linear variant of unfold. Note how they are implemented exactly identically. They could be merged if multiplicity polymorphism was supported.

Construct a Moore machine from a state valuation and transition function

To eveluate function repeatedly to construct a list of type LengthR n a. The function recieve a state and return a new state and an element value.

>>> :set -XDataKinds

>>> unfoldl (\n -> (n + 1, 2 * n)) 0 :: LengthR 5 Integer
((((NilR :+ 8) :+ 6) :+ 4) :+ 2) :+ 0