Examples/leq.chr

   1 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
   2 %%
   3 %% simple constraint solver for inequalities between variables
   4 %% thom fruehwirth ECRC 950519, LMU 980207, 980311
   5 %%
   6 %% ported to hProlog by Tom Schrijvers
   7
   8 :- module(leq,[]).
   9 :- use_module(library(chr)).
  10
  11 :- constraints leq/2.
  12 reflexivity  @ leq(X,X) <=> true.
  13 antisymmetry @ leq(X,Y), leq(Y,X) <=> X = Y.
  14 idempotence  @ leq(X,Y) \ leq(X,Y) <=> true.
  15 transitivity @ leq(X,Y), leq(Y,Z) ==> leq(X,Z).
  16
  17 time(N):-
  18         cputime(X),
  19         length(L,N),
  20         genleq(L,Last),
  21         L=[First|_],
  22         leq(Last,First),
  23         cputime( Now),
  24         Time is Now-X,
  25         write(N-Time), nl.
  26
  27 genleq([Last],Last) :- ! .
  28 genleq([X,Y|Xs],Last):-
  29         leq(X,Y),
  30         genleq([Y|Xs],Last).
  31
  32 cputime( Ts) :-
  33         statistics( runtime, [Tm,_]),
  34         Ts is Tm/1000.