42 lines
845 B
Plaintext
42 lines
845 B
Plaintext
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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%%
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%% Sieve of eratosthenes to compute primes
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%% thom fruehwirth 920218-20, 980311
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%% christian holzbaur 980207 for Sicstus CHR
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%%
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%% ported to hProlog by Tom Schrijvers
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:- module(primes,[primes/0]).
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:- use_module(library(chr)).
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:- chr_constraint candidate/1.
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:- chr_constraint prime/1.
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:- chr_constraint cleanup/1.
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:- chr_option(debug,off).
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:- chr_option(optimize,full).
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candidate(1) <=> true.
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candidate(N) <=> prime(N), N1 is N - 1, candidate(N1).
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absorb @ prime(Y) \ prime(X) <=> 0 =:= X mod Y | true.
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cleanup(_L), candidate(_X) <=> fail.
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cleanup(L), prime(N) <=> L = [N|T], cleanup(T).
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cleanup(L) <=> L = [].
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primes :-
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candidate(100),
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cleanup(L),
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sort(L,SL),
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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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