(* exemples de termes *)
let t1 = (* 5+3*5 *)
  TAdd(TInt 5, TMul(TInt 3,TInt 5))  

let t2 = (* fun x -> x*x *)
  TFun("x",TMul(TVar "x",TVar "x"))

let t3 = (* let f = fun x -> x*x in f (5+3*5) *)
  TLet("f",t2,TApp(TVar "f",t1))	    

let t4 = (* let y = 33 in fun x -> x*y *)
  TLet("y",TInt 33,TFun("x", TMul(TVar "x",TVar "y")))

let t5 = (* let f = (let y = 33 in fun x -> x*y) in f (5+3*5) *)
  TLet("f",t4,TApp(TVar "f",t1))

let t6 = (* let x = 3 in let f = fun y -> y * x in let x = 6 in f x *)
    TLet("x",TInt 3,TLet("f",TFun("y",TMul(TVar "y",TVar "x")),TLet("x",TInt
    6,TApp(TVar "f",TVar "x"))))

(* tests *)
let _ = eval empty_env t1		(* 20 *)
let _ = eval empty_env t2		(* <fun> *)
let _ = eval empty_env t3		(* 400 *)
let _ = eval empty_env t4		(* <fun> *)
let _ = eval empty_env t5		(* 660 *)
let _ = eval empty_env t6		(* 18 *)