tuned

--- a/src/HOL/Code_Numeral.thy	Thu Sep 18 18:48:04 2014 +0200
+++ b/src/HOL/Code_Numeral.thy	Thu Sep 18 18:48:04 2014 +0200
@@ -544,13 +544,10 @@
     and (Scala) "BigInt(0)"
 
 setup {*
-  fold (Numeral.add_code @{const_name Code_Numeral.Pos}
-    false Code_Printer.literal_numeral) ["SML", "OCaml", "Haskell", "Scala"]
-*}
-
-setup {*
-  fold (Numeral.add_code @{const_name Code_Numeral.Neg}
-    true Code_Printer.literal_numeral) ["SML", "OCaml", "Haskell", "Scala"]
+  fold (fn target =>
+    Numeral.add_code @{const_name Code_Numeral.Pos} I Code_Printer.literal_numeral target
+    #> Numeral.add_code @{const_name Code_Numeral.Neg} (op ~) Code_Printer.literal_numeral target)
+    ["SML", "OCaml", "Haskell", "Scala"]
 *}
 
 code_printing

--- a/src/HOL/Tools/numeral.ML	Thu Sep 18 18:48:04 2014 +0200
+++ b/src/HOL/Tools/numeral.ML	Thu Sep 18 18:48:04 2014 +0200
@@ -8,7 +8,7 @@
 sig
   val mk_cnumeral: int -> cterm
   val mk_cnumber: ctyp -> int -> cterm
-  val add_code: string -> bool -> (Code_Printer.literals -> int -> string) -> string -> theory -> theory
+  val add_code: string -> (int -> int) -> (Code_Printer.literals -> int -> string) -> string -> theory -> theory
 end;
 
 structure Numeral: NUMERAL =
@@ -65,9 +65,9 @@
 
 local open Basic_Code_Thingol in
 
-fun add_code number_of negative print target thy =
+fun add_code number_of preproc print target thy =
   let
-    fun dest_numeral thm t =
+    fun pretty literals _ thm _ _ [(t, _)] =
       let
         fun dest_bit (IConst { sym = Code_Symbol.Constant @{const_name Num.Bit0}, ... }) = 0
           | dest_bit (IConst { sym = Code_Symbol.Constant @{const_name Num.Bit1}, ... }) = 1
@@ -75,9 +75,7 @@
         fun dest_num (IConst { sym = Code_Symbol.Constant @{const_name Num.One}, ... }) = 1
           | dest_num (t1 `$ t2) = 2 * dest_num t2 + dest_bit t1
           | dest_num _ = Code_Printer.eqn_error thy thm "Illegal numeral expression: illegal term";
-      in if negative then ~ (dest_num t) else dest_num t end;
-    fun pretty literals _ thm _ _ [(t, _)] =
-      (Code_Printer.str o print literals o dest_numeral thm) t;
+      in (Code_Printer.str o print literals o preproc o dest_num) t end;
   in
     thy |> Code_Target.set_printings (Code_Symbol.Constant (number_of,
       [(target, SOME (Code_Printer.complex_const_syntax (1, pretty)))]))