`mkdir` will fail on Windows if the filename contains a colon
When executing mkdir "foo: bar Filesystem.createDirectory will fail:
*** Exception: CreateDirectory "F:\\": does not exist (The system cannot find the path specified.)
Now, this is an issue with Filesystem but since it is deprecated I don't think this will be fixed. I don't know what's the best course of action here.
Related https://github.com/Gabriel439/Haskell-Turtle-Library/issues/254
So like I mentioned in that issue I may take over maintainership of system-filepath soon so I can fix issues like these (or minimally just accept pull requests). However, I need to sort out some other tasks first before taking this on. Give me about a month before I can address this
Sure. This is a very minor issue, no need to rush. If I can help somehow let me know.
: is not a valid character to use in Windows filer or folder names:

So then, what would the solution be?
AFAIK a lot of these restrictions are only in the UI, and can be bypassed by using the raw APIs.