(*Exemples de termes*)
let a = Const 42;;
 let x = Variable "x";;
 let y = Variable "y";;
 let z = Variable "z";;

let a = Const 26;;
 let b = Const 19;;
let c = Const 20;;

 let f_addition=Fonction ("addition", List (Variable "x",[ (Variable "y")]));;
 let f_moyenne = Fonction ("moyenne", List (x, [y; z; a ]));;
let f_multiplication = Fonction ("multiplication", List (x, [y;z]));;
let f_soustraction = Fonction ("soustraction", List (x, [y;z]));;
 let f_max = Fonction ("max", List (x, [y; z]));;
let f_compose = Fonction ("compose", List (f_addition, [f_multiplication; f_soustraction]));;
let f_concat_strings = Fonction ("concat_strings", List (x, [y]));;