The goal of this current round of post related to difference list is to help convince @dtonhofer that accumulator passing uses difference list. It started with this post.
In so doing others will hopefully correct me if I am wrong somewhere, e.g. has_type/2 for difference list and what is a difference list, and help to ensure I am understanding difference list correctly.
When Jan W. has_type/2 for difference list correctly worked with the difference list unit tests I knew I had crossed a significant boundary.
Currently I am doing Visio diagrams with the pointer notation for closed list, open list, difference list and difference list used with accumulator passing. In so doing it makes me think about all of the details upon which I then learn something. If the diagrams work as expected I will post them here. They will be an SVG so that others can view them.