Effect of Readtable Case on the Lisp Reader
The readtable case of the current readtable affects the Lisp reader
in the following ways:
- :upcase
- When the readtable case is :upcase,
unescaped constituent characters are converted to uppercase,
as specified in Reader Algorithm.
- :downcase
- When the readtable case is :downcase,
unescaped constituent characters are converted to lowercase.
- :preserve
- When the readtable case is :preserve,
the case of all characters remains unchanged.
- :invert
- When the readtable case is :invert,
then if all of the unescaped letters in the extended token are of the same case,
those (unescaped) letters are converted to the opposite case.