Tests/primes.chr

   1 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
   2 %%
   3 %% Sieve of eratosthenes to compute primes
   4 %% thom fruehwirth 920218-20, 980311
   5 %% christian holzbaur 980207 for Sicstus CHR
   6 %%
   7 %% ported to hProlog by Tom Schrijvers
   8
   9 :- module(primes,[primes/0]).
  10 :- use_module(library(chr)).
  11
  12 :- chr_constraint candidate/1.
  13 :- chr_constraint prime/1.
  14 :- chr_constraint cleanup/1.
  15
  16 :- chr_option(debug,off).
  17 :- chr_option(optimize,full).
  18
  19 candidate(1) <=> true.
  20 candidate(N) <=> prime(N), N1 is N - 1, candidate(N1).
  21
  22 absorb @ prime(Y) \ prime(X) <=> 0 =:= X mod Y | true.
  23
  24 cleanup(_L), candidate(_X) <=> fail.
  25 cleanup(L), prime(N) <=> L = [N|T], cleanup(T).
  26 cleanup(L) <=> L = [].
  27
  28 primes :-
  29         candidate(100),
  30         cleanup(L),
  31         sort(L,SL),
  32         SL == [2,3,5,7,11,13,17,19,23,29,31,37,41,43,47,53,59,61,67,71,73,79,83,89,97].
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