type Content = [(Name Addr Tel?)*];;
type Addrbook = <addrbook>Content;;
type Name = <name>[String];;
type Addr = <addr>[String];;
type Tel = <tel>[String];;


<addrbook>[
  <name>["Haruo Hosoya"]
  <addr>["Tokyo"]
  <name>["Benjamin Pierce"]
  <addr>["Philadelphia"] 
  <tel>["123-456-789"]
  <name>["Peter Buneman"]
  <addr>["Scotland"]
 ];;
<addrbook>[
  <name>["Haruo Hosoya"]
  <addr>["Tokyo"]
  <name>["Benjamin Pierce"]
  <addr>["Philadelphia"] 
  <tel>["123-456-789"]
  <name>["Peter Buneman"]
  <addr>["Scotland"]
 ];;
<addrbook>[
  <name>["Haruo Hosoya"]
  <addr>["Tokyo"]
  <name>["Benjamin Pierce"]
  <addr>["Philadelphia"] 
  <tel>["123-456-789"]
  <name>["Peter Buneman"]
  <addr>["Scotland"]
 ];;
<addrbook>[
  <name>["Haruo Hosoya"]
  <addr>["Tokyo"]
  <name>["Benjamin Pierce"]
  <addr>["Philadelphia"] 
  <tel>["123-456-789"]
  <name>["Peter Buneman"]
  <addr>["Scotland"]
 ];;


(*

(* converting an address book into a telephone list *)

fun mkTelList ([ (Name Addr Tel?)* ] -> [ (Name Tel)* ])
| [ <name>n <addr>a <tel>t ; rest] -> [ <name>n <tel>t ; mkTelList rest] 
| [ <name>n <addr>a; rest] -> mkTelList rest
| [ ] -> [ ]
;;

fun mkTelList (Addrbook -> [ (Name Tel)* ])
<_>[ ( ( (x::Name) Addr (x::Tel) ) | _ )* ] ->  x
;;
*)

fun (Int -> Addrbook) x ->
<addrbook>[
  <name>["Haruo Hosoya"]
  <addr>["Tokyo"]
  <name>["Benjamin Pierce"]
  <addr>["Philadelphia"] 
  <tel>["123-456-789"]
  <name>["Peter Buneman"]
  <addr>["Scotland"]
 ] 
;;
(*
fun (Int -> Addrbook) x ->
<addrbook>[
  <name>["Haruo Hosoya"]
  <addr>["Tokyo"]
  <name>["Benjamin Pierce"]
  <addr>["Philadelphia"] 
  <tel>["123-456-789"]
  <name>["Peter Buneman"]
  <addr>["Scotland"]
 ] 
;;
*)


(*
match <addrbook>[
  <name>["Haruo Hosoya"]
  <addr>["Tokyo"]
  <name>["Benjamin Pierce"]
  <addr>["Philadelphia"] 
  <tel>["123-456-789"]
  <name>["Peter Buneman"]
  <addr>["Scotland"]
 ] with
<_>[ ( ( (x::Name) Addr (x::Tel) ) | _ )* ] ->  x;;

(*
(* the pattern extract the full sequence of subelements *)
match ex with addrbook:[;a] -> mkTelList a;;
*)

*)