src/Pure/term_xml.scala
author wenzelm
Fri Apr 12 14:54:14 2013 +0200 (2013-04-12)
changeset 51700 c8f2bad67dbb
parent 43779 47bec02c6762
child 70533 031620901fcd
permissions -rw-r--r--
tuned signature;
tuned comments;
     1 /*  Title:      Pure/term_xml.scala
     2     Author:     Makarius
     3 
     4 XML data representation of lambda terms.
     5 */
     6 
     7 package isabelle
     8 
     9 
    10 object Term_XML
    11 {
    12   import Term._
    13 
    14   object Encode
    15   {
    16     import XML.Encode._
    17 
    18     val sort: T[Sort] = list(string)
    19 
    20     def typ: T[Typ] =
    21       variant[Typ](List(
    22         { case Type(a, b) => (List(a), list(typ)(b)) },
    23         { case TFree(a, b) => (List(a), sort(b)) },
    24         { case TVar((a, b), c) => (List(a, int_atom(b)), sort(c)) }))
    25 
    26     def term: T[Term] =
    27       variant[Term](List(
    28         { case Const(a, b) => (List(a), typ(b)) },
    29         { case Free(a, b) => (List(a), typ(b)) },
    30         { case Var((a, b), c) => (List(a, int_atom(b)), typ(c)) },
    31         { case Bound(a) => (List(int_atom(a)), Nil) },
    32         { case Abs(a, b, c) => (List(a), pair(typ, term)(b, c)) },
    33         { case App(a, b) => (Nil, pair(term, term)(a, b)) }))
    34   }
    35 
    36   object Decode
    37   {
    38     import XML.Decode._
    39 
    40     val sort: T[Sort] = list(string)
    41 
    42     def typ: T[Typ] =
    43       variant[Typ](List(
    44         { case (List(a), b) => Type(a, list(typ)(b)) },
    45         { case (List(a), b) => TFree(a, sort(b)) },
    46         { case (List(a, b), c) => TVar((a, int_atom(b)), sort(c)) }))
    47 
    48     def term: T[Term] =
    49       variant[Term](List(
    50         { case (List(a), b) => Const(a, typ(b)) },
    51         { case (List(a), b) => Free(a, typ(b)) },
    52         { case (List(a, b), c) => Var((a, int_atom(b)), typ(c)) },
    53         { case (List(a), Nil) => Bound(int_atom(a)) },
    54         { case (List(a), b) => val (c, d) = pair(typ, term)(b); Abs(a, c, d) },
    55         { case (Nil, a) => val (b, c) = pair(term, term)(a); App(b, c) }))
    56   }
    57 }