(* type produit *)       

let x,s= (1,"bonjour");;

let f x = x,x;; 

(* type récursif *)

type intlist = NI | CI of int * intlist;;

let rec longueur_impaire l = match l with 
    NI -> true
    | CI(_,NI) -> false
    | CI(_,CI(_,lp)) -> longueur_impaire lp;;  

(* types polymorphes *)

type ('a,'b) couple = 'a*'b;;

let f  (c :('a,'b) couple) n =
    if n = 0 then fst c 
    else snd c;;

let g  (c :('a,'b) couple) n =
    if n = 0 then (fst c) +. 1. 
    else snd c;;