diff -r 151e76f0e3c7 -r bcf7544875b2 src/CCL/ex/Nat.thy
--- a/src/CCL/ex/Nat.thy	Sat Sep 17 14:02:31 2005 +0200
+++ b/src/CCL/ex/Nat.thy	Sat Sep 17 17:35:26 2005 +0200
@@ -1,38 +1,46 @@
-(*  Title:      CCL/ex/nat.thy
+(*  Title:      CCL/ex/Nat.thy
     ID:         $Id$
     Author:     Martin Coen, Cambridge University Computer Laboratory
     Copyright   1993  University of Cambridge
-
-Programs defined over the natural numbers
 *)
 
-Nat = Wfd +
+header {* Programs defined over the natural numbers *}
+
+theory Nat
+imports Wfd
+begin
 
 consts
 
-  not              :: "i=>i"
-  "#+","#*","#-",
-  "##","#<","#<="  :: "[i,i]=>i"            (infixr 60)
-  ackermann        :: "[i,i]=>i"
+  not   :: "i=>i"
+  "#+"  :: "[i,i]=>i"            (infixr 60)
+  "#*"  :: "[i,i]=>i"            (infixr 60)
+  "#-"  :: "[i,i]=>i"            (infixr 60)
+  "##"  :: "[i,i]=>i"            (infixr 60)
+  "#<"  :: "[i,i]=>i"            (infixr 60)
+  "#<=" :: "[i,i]=>i"            (infixr 60)
+  ackermann :: "[i,i]=>i"
 
-rules 
+defs
 
-  not_def     "not(b) == if b then false else true"
+  not_def:     "not(b) == if b then false else true"
 
-  add_def     "a #+ b == nrec(a,b,%x g. succ(g))"
-  mult_def    "a #* b == nrec(a,zero,%x g. b #+ g)"
-  sub_def     "a #- b == letrec sub x y be ncase(y,x,%yy. ncase(x,zero,%xx. sub(xx,yy))) 
+  add_def:     "a #+ b == nrec(a,b,%x g. succ(g))"
+  mult_def:    "a #* b == nrec(a,zero,%x g. b #+ g)"
+  sub_def:     "a #- b == letrec sub x y be ncase(y,x,%yy. ncase(x,zero,%xx. sub(xx,yy)))
                         in sub(a,b)"
-  le_def     "a #<= b == letrec le x y be ncase(x,true,%xx. ncase(y,false,%yy. le(xx,yy))) 
+  le_def:     "a #<= b == letrec le x y be ncase(x,true,%xx. ncase(y,false,%yy. le(xx,yy)))
                         in le(a,b)"
-  lt_def     "a #< b == not(b #<= a)"
+  lt_def:     "a #< b == not(b #<= a)"
 
-  div_def    "a ## b == letrec div x y be if x #< y then zero else succ(div(x#-y,y)) 
+  div_def:    "a ## b == letrec div x y be if x #< y then zero else succ(div(x#-y,y))
                        in div(a,b)"
-  ack_def    
-  "ackermann(a,b) == letrec ack n m be ncase(n,succ(m),%x. 
+  ack_def:
+  "ackermann(a,b) == letrec ack n m be ncase(n,succ(m),%x.
                           ncase(m,ack(x,succ(zero)),%y. ack(x,ack(succ(x),y))))
                     in ack(a,b)"
 
+ML {* use_legacy_bindings (the_context ()) *}
+
 end