Error Code Generator

Prolog code implemented using GNU Prolog

The philosophy of the error code constructed here -- not all errors derivable from the template are found -- is based on the following rules:

• + -- the argument shall be instantiated, only very simple type testing is done,
• - -- the argument shall be instantiated or a variable, again only very simple type testing is done,
• @ -- the argument shall remain unaltered,
• the argument shall be a variable.