// List type
(Head (Cons x xs)) = (Some x)
(Head Nil) = None

// Something like Rust's Option.unwrap_or
(UnwrapOr (Some x) y) = x
(UnwrapOr None y) = y

(SumFirstTwo Nil) = 0 
(SumFirstTwo (Cons x xs)) = (+ x (UnwrapOr (Head xs) 0))

// Iterate a function n times on an input
(Iter f x 0) = x
(Iter f x n) = (f (Iter f x (- n 1)))

(Fib n) = (Head (Iter λxs (Cons (SumFirstTwo xs) xs) (Cons 0 (Cons 1 Nil)) n))

(Main n) = (Tuple
  (Fib 10000)
  (Fib 10000)
  (Fib 10000)
  (Fib 10000)
  (Fib 10000)
  (Fib 10000)
  (Fib 10000)
  (Fib 10000)
)