let polynome a b c = fun x -> a * x * x + b * x + c

let g x y = 2 * x + y

let f x = g x x

let rec fact n =
  if n = 0 then 1
  else n * fact (pred n)

let rec pow2 x =
  if x = 0 then 1
  else 2 * pow2 (x - 1)

let rec pow2_log x =
  if x = 0 then 1
  else let y = pow2_log (x / 2) in
       let carre = y * y in
       if x mod 2 = 0 then carre
       else carre * 2

let identite  x y = x, y + 1

let compose f g = fun x -> g (f x)

let compose f g x = g (f x)