type Person = FPerson | MPerson;; 
type FPerson = <person gender = ['F'] >[ Name Children ];; 
type MPerson = <person gender="M">[ Name Children];; 
type Children = <children>[Person*];; 
type Name = <name>[ PCDATA ];;

type Man = <man name=String>[ Sons Daughters ];;
type Woman = <woman name=String>[ Sons Daughters ];;
type Sons = <sons>[ Man* ];;
type Daughters = <daughters>[ Woman* ];;

let fun sort (MPerson -> Man ; FPerson -> Woman)
   <person gender=g>[ <name>n <children>[(mc::MPerson | fc::FPerson)*] ] ->
       let tag = match g with "F" -> `woman | "M" -> `man in
       let s = map mc with x -> sort x in
       let d = map fc with x -> sort x in	
           <(tag) name=n>[ <sons>s  <daughters>d ] 
;; 
let base : Person = 
<person gender="F">[ 
  <name>"Veronique"
  <children>[ 
    <person gender="F">[
      <name>"Ilaria"
      <children>[]
     ]
  ]
]
;;

sort base;;

(* compilation efficace avec _ a la place de person *)
let fun name (Person | Man | Woman -> String)
  <person>[ <name>n ; _ ] 
| <_ name=n>_ -> n;;


name base;;
name (sort base);;