primes sieve from s s 0 from X cons X from s X head cons X Y X tail cons X Y Y if true X Y X if false X Y Y filter s s X cons Y Z if divides s s X Y filter s s X Z cons Y filter X sieve Y sieve cons X Y cons X filter X sieve Y primes 0 sieve 1 1 from 1 1 s 1 1 0 0 cons 2 1 head 1 1 tail 1 1 if 3 1 true 0 false 0 filter 2 1 2 divides 2 1 2 FULL ./TRS/CSR/ExIntrod_GM99.trs