2009/11/21 Robert Goldman rpgoldman@sift.info:
But that's just speculation. Could equally well be a simple oversight.
I've now had some coffee, so I'll speculate too:
I'm think downcasing was to make it convenient to have :case :local work, and not needing to name your system files FOO.asd. If system filename is going to be derived from the symbol name, then downcasing is an ugly but solid strategy to minimize portability issues (both when it comes to readtable case, modern mode, and case-sensitive vs insensitive filesystems.)
As for strings, I agree with your guess. Not case-folding strings allows for cased filenames if someone needs or wants them, and the read-syntax there is unambiguous: no sane Lisp is going to diddle the case of a string.
Cheers,
-- Nikodemus