Frequently I want to use reductions
only to quickly realize that I'm not interested in the successive values of the state.
A simple example is to imagine one wants to increment a number represented by a sequence of its binary digits:
(inc '()) is (1)
(inc '(1)) is (0 1) ; yes the list is inversed, the lowest significant bit is the first item
(inc '(0 1)) is (1 1)