This looks great. I am not sure about the different handling of globbing, because globbing seems more common on the command line's everyday use than complex indexing; double quotes are manageable and they could be the default outside top-level context. Zsh's "don't expand words but expand wildcards" seems like a nice middle ground.
Yeah I'm not entirely sold on my approach to globbing either. From an academic perspective I stand by my decision to make globbing functional. But from a usability perspective it kind of sucks.
The introduction of the `@g` prefix to allow inlined globbing does make things a little less painful but I'm honestly not sold on that solution either.
I'm open to suggestions / changing things up wrt globbing and will take another look at Zsh to see how they've addressed the problem.
The worst "accidental glob" is Windows Powershell, where square-brackets in filenames means you can't pipe from "ls" into other cmdlets because it interprets the square-brackets as filter commands even when they read them from the filesystem itself.
