-Inductive list (A:Set) : Set \def
-| nil : list A
-| cons : A \to list A \to list A.
-
-Inductive bool: Set \def
-| true : bool
-| false : bool.
-
-
-
-
-let rec len (A:Set)(l:list A) on l : nat \def
- match l:list with [
- nil \Rightarrow O
- | (cons e tl) \Rightarrow (S (len A tl))].