app :: list → list → list
cons :: nat → list → list
hshuffle :: (nat → nat) → list → list
nil :: list
reverse :: list → list
app(nil, X) → X
app(cons(Y, U), V) → cons(Y, app(U, V))
reverse(nil) → nil
reverse(cons(W, P)) → app(reverse(P), cons(W, nil))
hshuffle(F1, nil) → nil
hshuffle(Z1, cons(U1, V1)) → cons(Z1(U1), hshuffle(Z1, reverse(V1)))