More efficient `toUnfoldable` without the `Ord` constraint
More efficient `toUnfoldable` without the `Ord` constraint

Keep a List of Maps as the unfold state, instead of a single Map.
Unioning Maps was linear time (making the entire function quadratic?).
Prepending to a List is constant time and doesn't require an `Ord k` instance.

LiamGoodacre/purescript-maps,purescript/purescript-maps