src/Pure/term_xml.scala

         { case TFree(a, b) => (List(a), sort(b)) },
         { case TVar(Indexname(a, b), c) => (List(a, int_atom(b)), sort(c)) }))
 
     def term: T[Term] =
       variant[Term](List(
-        { case Const(a, b) => (List(a), typ(b)) },
+        { case Const(a, b) => (List(a), list(typ)(b)) },
         { case Free(a, b) => (List(a), typ(b)) },
         { case Var(Indexname(a, b), c) => (List(a, int_atom(b)), typ(c)) },
         { case Bound(a) => (List(int_atom(a)), Nil) },
         { case Abs(a, b, c) => (List(a), pair(typ, term)(b, c)) },
         { case App(a, b) => (Nil, pair(term, term)(a, b)) }))

         { case (List(a), b) => TFree(a, sort(b)) },
         { case (List(a, b), c) => TVar(Indexname(a, int_atom(b)), sort(c)) }))
 
     def term: T[Term] =
       variant[Term](List(
-        { case (List(a), b) => Const(a, typ(b)) },
+        { case (List(a), b) => Const(a, list(typ)(b)) },
         { case (List(a), b) => Free(a, typ(b)) },
         { case (List(a, b), c) => Var(Indexname(a, int_atom(b)), typ(c)) },
         { case (List(a), Nil) => Bound(int_atom(a)) },
         { case (List(a), b) => val (c, d) = pair(typ, term)(b); Abs(a, c, d) },
         { case (Nil, a) => val (b, c) = pair(term, term)(a); App(b, c) }))