Thanks for the feedback. Multiple posts are planned on that topic. For parts 1 and 2 (so far the only ones existing) I preferred explaining the context and the remarkable simplicity of the BZip2 format. In part #4, I will try to show why the customisable types in Ada fit so well compression software. Be patient: writing articles about writing software takes much more time than writing the software itself! In the meantime, there is a short preview of that in recent presentations - notably FOSDEM 2025: https://fosdem.org/2025/schedule/event/fosdem-2025-5148-adve... , last slide.