fib = fn f -> (
fn x -> if x == 0, do: 0, else: (if x == 1, do: 1, else: f.(x - 1) + f.(x - 2)) end
)
end
y = fn x -> (
fn f -> f.(f)
end).(
fn g -> x.(fn z ->(g.(g)).(z) end)
end)
IO.inspect y.(&(fib.(&1))).(40)