1.9 Version 1.9 Release Notes

Version 1.9 offers better portability including an MS-Windows 3.1 version. Changes to the Prolog system include:

• Redefinition of system predicates
  Redefinition of system predicates was allowed silently in older versions. Version 1.9 only allows it if the new definition is headed by a :- redefine_system_predicate/1 directive.
• `Answer' reuse
  The toplevel maintains a table of bindings returned by toplevel goals and allows for reuse of these bindings by prefixing the variables with the $ sign. See section 2.5.
• Better source code administration
  Allows for proper updating of multifile predicates and finding the sources of individual clauses.