There is nothing in the Prolog standard for converting case in textual data. The SWI-Prolog predicates code_type/2 and char_type/2 can be used to test and convert individual characters. We have started some additional support:
- downcase_atom(+AnyCase, -LowerCase)
- Converts the characters of AnyCase into lowercase as char_type/2 does (i.e. based on the defined locale if Prolog provides locale support on the hosting platform) and unifies the lowercase atom with LowerCase.
- upcase_atom(+AnyCase, -UpperCase)
- Converts, similar to downcase_atom/2, an atom to uppercase.