$//////////////////////////////////////////////////////////
$// Name: Peter M. Maurer
$// Program: Sieve of Eratosthenes
$// Due: Never
$// Language: SETL
$//////////////////////////////////////////////////////////
program SieveE;
    $ define the sieve data structure
    candidates := [1,1];
    i := 3;
    loop while i<1000 do
        $ everything is potentially prime until proven otherwise
        Candidates(i) := 1;
        i := i + 1;
    end loop;
    $ Neither 1 nor 0 is prime, so flag them off
    Candidates(1) := 0;
    $ start the sieve with the integer 1
    i := 1;
    loop while i<1000 do
        $ advance to the next un-crossed out number.
        $ this number must be a prime
        loop while i<1000 and Candidates(i) = 0 do
            i := i + 1;
        end loop;
        $ insure against running off the end of the data structure
        if i<1000 then
            $ cross out all multiples of the prime, starting with 2*p.
            j := 2;
            loop while j*i < 1000 do
                Candidates(j*i) := 0;
                j := j + 1;
            end loop;
            $ advance to the next candidate
            i := i + 1;
        end if;
    end loop;
    $ all uncrossed-out numbers are prime (and only those numbers)
    $ print all primes
    i := 1;
    loop while i<1000 do
        if Candidates(i) /= 0 then
            print(i,' is prime');
        end if;
        i := i + 1;
    end loop;
end program;