cons :: c → d → d
f :: a → a → a
false :: b
filter :: (c → b) → d → d
filter2 :: b → (c → b) → c → d → d
g :: a → a
h :: a → a
map :: (c → c) → d → d
nil :: d
true :: b
g(h(g(X))) → g(X)
g(g(Y)) → g(h(g(Y)))
h(h(U)) → h(f(h(U), U))
map(H, nil) → nil
map(I, cons(P, X1)) → cons(I(P), map(I, X1))
filter(Z1, nil) → nil
filter(G1, cons(V1, W1)) → filter2(G1(V1), G1, V1, W1)
filter2(true, J1, X2, Y2) → cons(X2, filter(J1, Y2))
filter2(false, G2, V2, W2) → filter(G2, W2)