(STRATEGY
    INNERMOST)

(VAR
    M N X)
(DATATYPES
    A = µX.< cons(X), 0, s(X) >)
(SIGNATURES
    filter :: [A x A x A] -> A
    sieve :: [A] -> A
    nats :: [A] -> A
    zprimes :: [] -> A)
(RULES
    filter(cons(X),0(),M) ->
      cons(0())
    filter(cons(X),s(N),M) ->
      cons(X)
    sieve(cons(0())) -> cons(0())
    sieve(cons(s(N))) -> cons(s(N))
    nats(N) -> cons(N)
    zprimes() ->
      sieve(nats(s(s(0())))))