May 27, 2026
Patch me if you can
Interleaved Deltas
This old-school file-saving trick has nerds fighting over whether the past was secretly smarter
TLDR: A programmer unpacked a little-known 1970s way of storing file history and turned it into a readable modern guide. Readers loved the vintage brilliance but argued hard over whether it’s timeless genius or exactly the kind of cleverness best left in the past.
A deep-dive post about how old software saved different versions of a file somehow turned into a full-blown comment-section personality test. The article itself is a love letter to an ancient method from the 1970s called a “weave,” where every change to a file gets stitched together so older versions can be rebuilt later. The author basically says: modern tools like Git feel elegantly simple, but this older system was weird, clever, and a little intimidating—so they went off, decoded it, and published their own guide and code for future adventurers.
But the real fireworks came from the crowd. One camp was instantly smitten, calling it a lost gem from an era when programmers had to be ridiculously efficient. These commenters were in full “our ancestors were wizards” mode, praising the idea as brilliant, compact, and proof that old-school engineers squeezed miracles out of tiny machines. The other camp had a very different reaction: cool history lesson, absolutely not using this on purpose. They joked that “reinvented a thousand times” is not a flex, it’s a warning label.
And yes, the jokes landed. People compared the format to archaeology, knitting, and reading cursed sheet music written by a time traveler. Others loved the drama of the author admitting even a famous reference implementation felt impossible to read. That confession won hearts fast: if you’ve ever opened old code and immediately questioned your life choices, the comments made it clear—you were seen.
Key Points
- •The article explains interleaved deltas, or weaves, as a data structure for reconstructing file revisions.
- •It places weaves in the historical context of SCCS, which Marc J. Rochkind developed in the early 1970s to manage revisions one file at a time.
- •The article contrasts simple snapshot-based version control ideas and content addressing with Git’s design to motivate discussion of storage structures.
- •It cites limited available resources on weaves, including the BitKeeper wiki, Bram Cohen’s reference implementation, and the author’s `roman-kashitsyn/weaver` repository.
- •The technical section defines four weave instruction types—`Line`, `BeginInsert`, `BeginDelete`, and `End`—and shows a Go representation of instructions and payload handling.