/*                      Scratch Pad Utility */
domains
       name = symbol

database
        sp(name,real)

predicates
         remember(name,real)
         recall(name,real)
         forget(name)
         set_count(name)
         count_up(name,real)
         clr_sp
         disp_sp
         plus_sp(name,real,real)
         minus_sp(name,real,real)

clauses
       remember(Name,Value) :- asserta(sp(Name,Value)).

       forget(Name) :- retract(sp(Name,_)).

       recall(Name,Value) :- sp(Name,Value).

       set_count(Name) :- asserta(sp(Name,0)).

       count_up(Name,Value1) :- retract(sp(Name,Value)),
                                Value1=Value+1,
                                asserta(sp(Name,Value1)),!.

       clr_sp :- retract(sp(_,_)),fail.

       disp_sp :- sp(Name,Value),
                  write(Name,"\t",Value),nl,fail.

       plus_sp(Name,Addend,Newvalue) :- recall(Name,Value),
                                        Newvalue=Value+Addend,
                                        forget(Name),
                                        remember(Name,Newvalue).

       minus_sp(Name,Addend,Newvalue) :- recall(Name,Value),
                                         Newvalue=Value-Addend,
                                         forget(Name),
                                         remember(Name,Newvalue).