"On Linux, ~/ is the home directory of the current user, so it makes sense that Anarki would work that way on Linux. But Windows doesn't work that way, so it makes sense Anarki wouldn't either."
Yeah, I don't know much about what a Windows user would expect ~ to do. I would say `expand-user-path` leaving ~ alone on Windows is probably as good a behavior as any. It coincides with Command Prompt, where ~ just refers to a file or folder named "~". In PowerShell, ~ seems to be expanded to C:\Users\[username]\ somehow, so there's potentially an alternative design there.
"I don't know of any similar path tricks on Windows, But, if this change hasn't broken anything on Windows, I would be satisfied with that. Can you verify it still works to open an existing file?"
On Windows 10 64-bit with Racket 8.1, I've at least run the tests.arc unit tests, the unit-test.arc/tests.arc unit tests, and build-web-help.arc, and they seem to work.
"Are there any other special ways to refer to files or directories on Windows?"
I hardly know where to begin learning about and testing those features, and the documentation makes it look like Racket has explored hat rabbit hole pretty thoroughly already, so I'm inclined to suggest we just piggyback on Racket's work here.