Normalize the given UTF-8 encoded string. Invalid UTF-8 sequences results in a error and are replaced by U+FFFD. Identifier characters are put in NFC normalized form. Other Unicode characters are left unchanged.

Like normalize, but if the string starts with a lowercase identifier character, it is replaced by the corresponding uppercase character. Subsequent characters are not changed.

Like normalize, but if the string starts with an uppercase identifier character, it is replaced by the corresponding lowercase character. Subsequent characters are not changed.

Returns true if the given normalized string starts with an uppercase identifier character, false otherwise. May return wrong results if the string is not normalized.

Check whether the given normalized string is a valid OCaml identifier:

• all characters are identifier characters
• it does not start with a digit or a single quote

Returns true if the given normalized string only contains lowercase identifier character, false otherwise. May return wrong results if the string is not normalized.

Like is_valid_identifier, but returns a more detailed error code. Dots can be allowed to extend support to path-like identifiers.

Checks whether the given normalized string starts with an identifier character other than a digit or a single quote. Subsequent characters are not checked.