a__primes a__sieve a__from s s 0 a__from X cons mark X from s X a__head cons X Y mark X a__tail cons X Y mark Y a__if true X Y mark X a__if false X Y mark Y a__filter s s X cons Y Z a__if divides s s mark X mark Y filter s s X Z cons Y filter X sieve Y a__sieve cons X Y cons mark X filter X sieve Y mark primes a__primes mark sieve X a__sieve mark X mark from X a__from mark X mark head X a__head mark X mark tail X a__tail mark X mark if X1 X2 X3 a__if mark X1 X2 X3 mark filter X1 X2 a__filter mark X1 mark X2 mark s X s mark X mark 0 0 mark cons X1 X2 cons mark X1 X2 mark true true mark false false mark divides X1 X2 divides mark X1 mark X2 a__primes primes a__sieve X sieve X a__from X from X a__head X head X a__tail X tail X a__if X1 X2 X3 if X1 X2 X3 a__filter X1 X2 filter X1 X2 a__primes 0 a__sieve 1 a__from 1 s 1 0 0 cons 2 mark 1 from 1 a__head 1 a__tail 1 a__if 3 true 0 false 0 a__filter 2 divides 2 filter 2 sieve 1 primes 0 head 1 tail 1 if 3 INNERMOST ./TRS/TRCSR/inn/ExIntrod_GM99_GM.trs