Lazily consuming a self-referential linked list

tobz619: > VegOwOtenks: > >> >> go :: [q] -> s -> (q -> s -> [q] -> ([q], s)) -> ([q], s) >> go qs s0 f = case qs of >> [] -> ([], s0) >> q:rest -> let >> (qs1, s1) = f q s0 qs2 -- why is this qs2 and not rest? >> (qs2, s2) = go rest s1 f -- why is this rest and not qs1? >> in (qs1, s2) -- why is this qs1 and not qs2? >> The order is like this because it allows the list that is build-up to travel-backwards along the computation, like it would with TardisT. This enables cheap list-building (only cons, no concatenation) while preserving FIFO semantics.