/* 

  Generate primes in Picat.


  This Picat model was created by Hakan Kjellerstrand, hakank@gmail.com
  See also my Picat page: http://www.hakank.org/picat/

*/

import util.

main => go.

go ?=>
 gen(P),
 println(P),
 fail.

go => true.

go2 ?=>
  gen(P),
  println(P),
  (P >= 10000 ; fail).
go2 => true.

% Another approach using member/2
go3 ?=> 
  member(P, [I : I in 2..10000, prime(I)]),
  println(P),
  fail.

go3 => true.

% Generate primes
gen(N) => 
  next_prime(2,N).

% Num is a prime
next_prime(Num, P), prime(Num) ?=> 
  P = Num.

% step to next prime
next_prime(Num, P) ?=>
  (Num <= 2 -> 
    Num2 = Num + 1
  ;
    Num2 = Num + 2
  ),
  next_prime(Num2,P).