We're moving toward retiring the Python tarball: OSH differs by 2 test cases in C++, and YSH differs by 77, down from 157 in the last release.
We're deep in the middle of implementing YSH: particularly functions, procs, and data languages. We're constantly testing and revising the language design.
Another highlight is the new Oils Reference, organized into two tables of contents, and 13 chapters. As YSH stabilizes, we'll document its behavior here.
But programs that want to scrape bash completion can only see the logic in $wrapper, not the three -o options. See Projects Already Doing Something Like Shellac for such programs.
It was motivated both by testing our completion logic (escaping), and the headless shell. We want to export shell completions to a GUI. But again, I think other programs can also use it, rather than scraping bash and re-implementing parts of it.
The is-main builtin returns 1 (false) if the current file was executed with the source builtin. It's designed to be used like Python: