diff --git a/src/HOL/Library/code_test.ML b/src/HOL/Library/code_test.ML
--- a/src/HOL/Library/code_test.ML
+++ b/src/HOL/Library/code_test.ML
@@ -1,557 +1,555 @@
 (*  Title:      HOL/Library/code_test.ML
     Author:     Andreas Lochbihler, ETH Zürich
 
 Test infrastructure for the code generator.
 *)
 
 signature CODE_TEST =
 sig
   val add_driver:
     string * ((Proof.context -> (string * string) list * string -> Path.T -> string) * string) ->
     theory -> theory
   val debug: bool Config.T
   val successN: string
   val failureN: string
   val start_markerN: string
   val end_markerN: string
   val test_terms: Proof.context -> term list -> string -> unit
   val test_code_cmd: string list -> string list -> Proof.context -> unit
   val eval_term: string -> Proof.context -> term -> term
   val check_settings: string -> string -> string -> unit
   val compile: string -> string -> unit
   val evaluate: string -> string -> string
   val evaluate_in_polyml: Proof.context -> (string * string) list * string -> Path.T -> string
   val evaluate_in_mlton: Proof.context -> (string * string) list * string -> Path.T -> string
   val evaluate_in_smlnj: Proof.context -> (string * string) list * string -> Path.T -> string
   val evaluate_in_ocaml: Proof.context -> (string * string) list * string -> Path.T -> string
   val ghc_options: string Config.T
   val evaluate_in_ghc: Proof.context -> (string * string) list * string -> Path.T -> string
   val evaluate_in_scala: Proof.context -> (string * string) list * string -> Path.T -> string
   val target_Scala: string
   val target_Haskell: string
 end
 
 structure Code_Test: CODE_TEST =
 struct
 
 (* convert a list of terms into nested tuples and back *)
 
 fun mk_tuples [] = \<^term>\<open>()\<close>
   | mk_tuples [t] = t
   | mk_tuples (t :: ts) = HOLogic.mk_prod (t, mk_tuples ts)
 
 fun dest_tuples (Const (\<^const_name>\<open>Pair\<close>, _) $ l $ r) = l :: dest_tuples r
   | dest_tuples t = [t]
 
 
 fun last_field sep str =
   let
     val n = size sep
     val len = size str
     fun find i =
       if i < 0 then NONE
       else if String.substring (str, i, n) = sep then SOME i
       else find (i - 1)
   in
     (case find (len - n) of
       NONE => NONE
     | SOME i => SOME (String.substring (str, 0, i), String.extract (str, i + n, NONE)))
   end
 
 fun split_first_last start stop s =
   (case first_field start s of
     NONE => NONE
   | SOME (initial, rest) =>
       (case last_field stop rest of
         NONE => NONE
       | SOME (middle, tail) => SOME (initial, middle, tail)))
 
 
 (* data slot for drivers *)
 
 structure Drivers = Theory_Data
 (
   type T =
     (string * ((Proof.context -> (string * string) list * string -> Path.T -> string) * string)) list
   val empty = []
   val extend = I
   fun merge data : T = AList.merge (op =) (K true) data
 )
 
 val add_driver = Drivers.map o AList.update (op =)
 val get_driver = AList.lookup (op =) o Drivers.get
 
 (*
   Test drivers must produce output of the following format:
 
   The start of the relevant data is marked with start_markerN,
   its end with end_markerN.
 
   Between these two markers, every line corresponds to one test.
   Lines of successful tests start with successN, failures start with failureN.
   The failure failureN may continue with the YXML encoding of the evaluated term.
   There must not be any additional whitespace in between.
 *)
 
 
 (* parsing of results *)
 
 val successN = "True"
 val failureN = "False"
 val start_markerN = "*@*Isabelle/Code_Test-start*@*"
 val end_markerN = "*@*Isabelle/Code_Test-end*@*"
 
 fun parse_line line =
   if String.isPrefix successN line then (true, NONE)
   else if String.isPrefix failureN line then (false,
     if size line > size failureN then
       String.extract (line, size failureN, NONE)
       |> YXML.parse_body
       |> Term_XML.Decode.term_raw
       |> dest_tuples
       |> SOME
     else NONE)
   else raise Fail ("Cannot parse result of evaluation:\n" ^ line)
 
 fun parse_result target out =
   (case split_first_last start_markerN end_markerN out of
     NONE => error ("Evaluation failed for " ^ target ^ "!\nCompiler output:\n" ^ out)
   | SOME (_, middle, _) => middle |> trim_split_lines |> map parse_line)
 
 
 (* pretty printing of test results *)
 
 fun pretty_eval _ NONE _ = []
   | pretty_eval ctxt (SOME evals) ts =
       [Pretty.fbrk,
        Pretty.big_list "Evaluated terms"
          (map (fn (t, eval) => Pretty.block
            [Syntax.pretty_term ctxt t, Pretty.brk 1, Pretty.str "=", Pretty.brk 1,
             Syntax.pretty_term ctxt eval])
          (ts ~~ evals))]
 
 fun pretty_failure ctxt target (((_, evals), query), eval_ts) =
   Pretty.block (Pretty.text ("Test in " ^ target ^ " failed for") @
     [Pretty.brk 1, Pretty.quote (Syntax.pretty_term ctxt query)] @
     pretty_eval ctxt evals eval_ts)
 
 fun pretty_failures ctxt target failures =
   Pretty.blk (0, Pretty.fbreaks (map (pretty_failure ctxt target) failures))
 
 
 (* driver invocation *)
 
 val debug = Attrib.setup_config_bool \<^binding>\<open>test_code_debug\<close> (K false)
 
 fun with_debug_dir name f =
   let
     val dir =
       Path.append (Path.explode "$ISABELLE_HOME_USER") (Path.basic (name ^ serial_string ()))
     val _ = Isabelle_System.mkdirs dir
   in Exn.release (Exn.capture f dir) end
 
 fun dynamic_value_strict ctxt t compiler =
   let
     val thy = Proof_Context.theory_of ctxt
     val (driver, target) =
       (case get_driver thy compiler of
         NONE => error ("No driver for target " ^ compiler)
       | SOME drv => drv)
     val with_dir = if Config.get ctxt debug then with_debug_dir else Isabelle_System.with_tmp_dir
     fun eval result =
       with_dir "Code_Test" (driver ctxt ((apfst o map o apfst) Long_Name.implode result))
       |> parse_result compiler
     fun evaluator program _ vs_ty deps =
       Exn.interruptible_capture eval
         (Code_Target.compilation_text ctxt target program deps true vs_ty)
     fun postproc f = map (apsnd (Option.map (map f)))
   in Exn.release (Code_Thingol.dynamic_value ctxt (Exn.map_res o postproc) evaluator t) end
 
 
 (* term preprocessing *)
 
 fun add_eval (Const (\<^const_name>\<open>Trueprop\<close>, _) $ t) = add_eval t
   | add_eval (Const (\<^const_name>\<open>HOL.eq\<close>, _) $ lhs $ rhs) = (fn acc =>
       acc
       |> add_eval rhs
       |> add_eval lhs
       |> cons rhs
       |> cons lhs)
   | add_eval (Const (\<^const_name>\<open>Not\<close>, _) $ t) = add_eval t
   | add_eval (Const (\<^const_name>\<open>Orderings.ord_class.less_eq\<close>, _) $ lhs $ rhs) = (fn acc =>
       lhs :: rhs :: acc)
   | add_eval (Const (\<^const_name>\<open>Orderings.ord_class.less\<close>, _) $ lhs $ rhs) = (fn acc =>
       lhs :: rhs :: acc)
   | add_eval _ = I
 
 fun mk_term_of [] = \<^term>\<open>None :: (unit \<Rightarrow> yxml_of_term) option\<close>
   | mk_term_of ts =
       let
         val tuple = mk_tuples ts
         val T = fastype_of tuple
       in
         \<^term>\<open>Some :: (unit \<Rightarrow> yxml_of_term) \<Rightarrow> (unit \<Rightarrow> yxml_of_term) option\<close> $
           (absdummy \<^typ>\<open>unit\<close> (\<^const>\<open>yxml_string_of_term\<close> $
             (Const (\<^const_name>\<open>Code_Evaluation.term_of\<close>, T --> \<^typ>\<open>term\<close>) $ tuple)))
       end
 
 fun test_terms ctxt ts target =
   let
     val thy = Proof_Context.theory_of ctxt
 
     fun term_of t = Sign.of_sort thy (fastype_of t, \<^sort>\<open>term_of\<close>)
 
     fun ensure_bool t =
       (case fastype_of t of
         \<^typ>\<open>bool\<close> => ()
       | _ =>
         error (Pretty.string_of
           (Pretty.block [Pretty.str "Test case not of type bool:", Pretty.brk 1,
             Syntax.pretty_term ctxt t])))
 
     val _ = List.app ensure_bool ts
 
     val evals = map (fn t => filter term_of (add_eval t [])) ts
     val eval = map mk_term_of evals
 
     val t =
       HOLogic.mk_list \<^typ>\<open>bool \<times> (unit \<Rightarrow> yxml_of_term) option\<close>
         (map HOLogic.mk_prod (ts ~~ eval))
 
     val result = dynamic_value_strict ctxt t target
 
     val failed =
       filter_out (fst o fst o fst) (result ~~ ts ~~ evals)
       handle ListPair.UnequalLengths =>
         error ("Evaluation failed!\nWrong number of test results: " ^ string_of_int (length result))
   in
     (case failed of
       [] => ()
     | _ => error (Pretty.string_of (pretty_failures ctxt target failed)))
   end
 
 fun test_code_cmd raw_ts targets ctxt =
   let
     val ts = Syntax.read_terms ctxt raw_ts
     val frees = fold Term.add_frees ts []
     val _ =
       if null frees then ()
       else error (Pretty.string_of
         (Pretty.block (Pretty.str "Terms contain free variables:" :: Pretty.brk 1 ::
           Pretty.commas (map (Syntax.pretty_term ctxt o Free) frees))))
   in List.app (test_terms ctxt ts) targets end
 
 fun eval_term target ctxt t =
   let
     val frees = Term.add_frees t []
     val _ =
       if null frees then ()
       else
         error (Pretty.string_of
           (Pretty.block (Pretty.str "Term contains free variables:" :: Pretty.brk 1 ::
             Pretty.commas (map (Syntax.pretty_term ctxt o Free) frees))))
 
     val T = fastype_of t
     val _ =
       if Sign.of_sort (Proof_Context.theory_of ctxt) (T, \<^sort>\<open>term_of\<close>) then ()
       else error ("Type " ^ Syntax.string_of_typ ctxt T ^
        " of term not of sort " ^ Syntax.string_of_sort ctxt \<^sort>\<open>term_of\<close>)
 
     val t' =
       HOLogic.mk_list \<^typ>\<open>bool \<times> (unit \<Rightarrow> yxml_of_term) option\<close>
         [HOLogic.mk_prod (\<^term>\<open>False\<close>, mk_term_of [t])]
 
     val result = dynamic_value_strict ctxt t' target
   in (case result of [(_, SOME [t])] => t | _ => error "Evaluation failed") end
 
 
 (* check and invoke compiler *)
 
 fun check_settings compiler var descr =
   if getenv var = "" then
     error (Pretty.string_of (Pretty.para
       ("Environment variable " ^ var ^ " is not set. To test code generation with " ^
         compiler ^ ", set this variable to your " ^ descr ^
         " in the $ISABELLE_HOME_USER/etc/settings file.")))
   else ();
 
 fun compile compiler cmd =
   let val (out, ret) = Isabelle_System.bash_output cmd in
     if ret = 0 then ()
     else error ("Compilation with " ^ compiler ^ " failed:\n" ^ cmd ^ "\n" ^ out)
   end
 
 fun evaluate compiler cmd =
   let val (out, res) = Isabelle_System.bash_output cmd in
     if res = 0 then out
     else error ("Evaluation for " ^ compiler ^ " terminated with error code " ^
       string_of_int res ^ "\nCompiler output:\n" ^ out)
   end
 
 
 (* driver for PolyML *)
 
 val polymlN = "PolyML"
 
-fun evaluate_in_polyml ctxt (code_files, value_name) dir =
+fun evaluate_in_polyml (_: Proof.context) (code_files, value_name) dir =
   let
-    val code = #2 (the_single code_files);
     val code_path = Path.append dir (Path.basic "generated.sml")
     val driver_path = Path.append dir (Path.basic "driver.sml")
     val out_path = Path.append dir (Path.basic "out")
+
+    val code = #2 (the_single code_files);
     val driver = \<^verbatim>\<open>
 fun main () =
   let
     fun format (true, _) = \<close> ^ ML_Syntax.print_string successN ^ \<^verbatim>\<open> ^ "\n"
       | format (false, NONE) = \<close> ^ ML_Syntax.print_string failureN ^ \<^verbatim>\<open> ^ "\n"
       | format (false, SOME t) = \<close> ^ ML_Syntax.print_string failureN ^ \<^verbatim>\<open> ^ t () ^ "\n"
     val result = \<close> ^ value_name ^ \<^verbatim>\<open> ()
     val result_text = \<close> ^
       ML_Syntax.print_string start_markerN ^
       \<^verbatim>\<open> ^ String.concat (map format result) ^ \<close> ^
       ML_Syntax.print_string end_markerN ^ \<^verbatim>\<open>
     val out = BinIO.openOut \<close> ^ ML_Syntax.print_platform_path out_path ^ \<^verbatim>\<open>
     val _ = BinIO.output (out, Byte.stringToBytes result_text)
     val _ = BinIO.closeOut out
   in () end;
 \<close>
   in
-    if Config.get ctxt debug
-    then (File.write code_path code; File.write driver_path driver)
-    else ();
-
+    File.write code_path code;
+    File.write driver_path driver;
     ML_Context.eval
       {environment = ML_Env.SML, redirect = false, verbose = false, debug = NONE,
         writeln = writeln, warning = warning}
       Position.none
       (ML_Lex.read_text (code, Path.position code_path) @
        ML_Lex.read_text (driver, Path.position driver_path) @
        ML_Lex.read "main ()");
-
     File.read out_path
   end
 
 
 (* driver for mlton *)
 
 val mltonN = "MLton"
 val ISABELLE_MLTON = "ISABELLE_MLTON"
 
 fun evaluate_in_mlton (_: Proof.context) (code_files, value_name) dir =
   let
     val compiler = mltonN
     val generatedN = "generated.sml"
     val driverN = "driver.sml"
     val projectN = "test"
 
     val code_path = Path.append dir (Path.basic generatedN)
     val driver_path = Path.append dir (Path.basic driverN)
     val basis_path = Path.append dir (Path.basic (projectN ^ ".mlb"))
     val driver = \<^verbatim>\<open>
 fun format (true, _) = \<close> ^ ML_Syntax.print_string successN ^ \<^verbatim>\<open> ^ "\n"
   | format (false, NONE) = \<close> ^ ML_Syntax.print_string failureN ^ \<^verbatim>\<open> ^ "\n"
   | format (false, SOME t) = \<close> ^ ML_Syntax.print_string failureN ^ \<^verbatim>\<open> ^ t () ^ "\n"
 val result = \<close> ^ value_name ^ \<^verbatim>\<open> ()
 val _ = print \<close> ^ ML_Syntax.print_string start_markerN ^ \<^verbatim>\<open>
 val _ = List.app (print o format) result
 val _ = print \<close> ^ ML_Syntax.print_string end_markerN ^ \<^verbatim>\<open>
 \<close>
     val cmd = "\"$ISABELLE_MLTON\" -default-type intinf " ^ File.bash_path basis_path
   in
     check_settings compiler ISABELLE_MLTON "MLton executable";
     List.app (File.write code_path o snd) code_files;
     File.write driver_path driver;
     File.write basis_path ("$(SML_LIB)/basis/basis.mlb\n" ^ generatedN ^ "\n" ^ driverN);
     compile compiler cmd;
     evaluate compiler (File.bash_path (Path.append dir (Path.basic projectN)))
   end
 
 
 (* driver for SML/NJ *)
 
 val smlnjN = "SMLNJ"
 val ISABELLE_SMLNJ = "ISABELLE_SMLNJ"
 
 fun evaluate_in_smlnj (_: Proof.context) (code_files, value_name) dir =
   let
     val compiler = smlnjN
     val generatedN = "generated.sml"
     val driverN = "driver.sml"
 
     val code_path = Path.append dir (Path.basic generatedN)
     val driver_path = Path.append dir (Path.basic driverN)
     val driver = \<^verbatim>\<open>
 structure Test =
 struct
   fun main () =
     let
       fun format (true, _) = \<close> ^ ML_Syntax.print_string successN ^ \<^verbatim>\<open> ^ "\n"
         | format (false, NONE) = \<close> ^ ML_Syntax.print_string failureN ^ \<^verbatim>\<open> ^ "\n"
         | format (false, SOME t) = \<close> ^ ML_Syntax.print_string failureN ^ \<^verbatim>\<open> ^ t () ^ "\n"
       val result = \<close> ^ value_name ^ \<^verbatim>\<open> ()
       val _ = print \<close> ^ ML_Syntax.print_string start_markerN ^ \<^verbatim>\<open>
       val _ = List.app (print o format) result
       val _ = print \<close> ^ ML_Syntax.print_string end_markerN ^ \<^verbatim>\<open>
     in 0 end
 end
 \<close>
     val ml_source =
       "Control.MC.matchRedundantError := false; Control.MC.matchRedundantWarn := false;" ^
       "use " ^ ML_Syntax.print_string (File.platform_path code_path) ^
       "; use " ^ ML_Syntax.print_string (File.platform_path driver_path) ^
       "; Test.main ();"
   in
     check_settings compiler ISABELLE_SMLNJ "SMLNJ executable";
     List.app (File.write code_path o snd) code_files;
     File.write driver_path driver;
     evaluate compiler ("echo " ^ Bash.string ml_source ^ " | \"$ISABELLE_SMLNJ\"")
   end
 
 
 (* driver for OCaml *)
 
 val ocamlN = "OCaml"
 val ISABELLE_OCAMLFIND = "ISABELLE_OCAMLFIND"
 
 fun evaluate_in_ocaml (_: Proof.context) (code_files, value_name) dir =
   let
     val compiler = ocamlN
 
     val code_path = Path.append dir (Path.basic "generated.ml")
     val driver_path = Path.append dir (Path.basic "driver.ml")
     val driver =
       "let format_term = function\n" ^
       "  | None -> \"\"\n" ^
       "  | Some t -> t ();;\n" ^
       "let format = function\n" ^
       "  | (true, _) -> \"" ^ successN ^ "\\n\"\n" ^
       "  | (false, x) -> \"" ^ failureN ^ "\" ^ format_term x ^ \"\\n\";;\n" ^
       "let result = " ^ ("Generated." ^ value_name) ^ " ();;\n" ^
       "let main x =\n" ^
       "  let _ = print_string \"" ^ start_markerN ^ "\" in\n" ^
       "  let _ = List.map (fun x -> print_string (format x)) result in\n" ^
       "  print_string \"" ^ end_markerN ^ "\";;\n" ^
       "main ();;"
     val compiled_path = Path.append dir (Path.basic "test")
     val cmd =
       "\"$ISABELLE_OCAMLFIND\" ocamlopt -w pu -package zarith -linkpkg" ^
       " -o " ^ File.bash_path compiled_path ^ " -I " ^ File.bash_path dir ^ " " ^
       File.bash_path code_path ^ " " ^ File.bash_path driver_path ^ " </dev/null"
   in
     check_settings compiler ISABELLE_OCAMLFIND "ocamlfind executable";
     List.app (File.write code_path o snd) code_files;
     File.write driver_path driver;
     compile compiler cmd;
     evaluate compiler (File.bash_path compiled_path)
   end
 
 
 (* driver for GHC *)
 
 val ghcN = "GHC"
 val ISABELLE_GHC = "ISABELLE_GHC"
 
 val ghc_options = Attrib.setup_config_string \<^binding>\<open>code_test_ghc\<close> (K "")
 
 fun evaluate_in_ghc ctxt (code_files, value_name) dir =
   let
     val compiler = ghcN
     val modules = map fst code_files
 
     val driver_path = Path.append dir (Path.basic "Main.hs")
     val driver =
       "module Main where {\n" ^
       implode (map (fn module => "import qualified " ^ unsuffix ".hs" module ^ ";\n") modules) ^
       "main = do {\n" ^
       "    let {\n" ^
       "      format_term Nothing = \"\";\n" ^
       "      format_term (Just t) = t ();\n" ^
       "      format (True, _) = \"" ^ successN ^ "\\n\";\n" ^
       "      format (False, to) = \"" ^ failureN ^ "\" ++ format_term to ++ \"\\n\";\n" ^
       "      result = " ^ value_name ^ " ();\n" ^
       "    };\n" ^
       "    Prelude.putStr \"" ^ start_markerN ^ "\";\n" ^
       "    Prelude.mapM_ (putStr . format) result;\n" ^
       "    Prelude.putStr \"" ^ end_markerN ^ "\";\n" ^
       "  }\n" ^
       "}\n"
 
     val compiled_path = Path.append dir (Path.basic "test")
     val cmd =
       "\"$ISABELLE_GHC\" " ^ Code_Haskell.language_params ^ " " ^
       Config.get ctxt ghc_options ^ " -o " ^
       File.bash_platform_path compiled_path ^ " " ^
       File.bash_platform_path driver_path ^ " -i" ^
       File.bash_platform_path dir
   in
     check_settings compiler ISABELLE_GHC "GHC executable";
     List.app (fn (name, code) => File.write (Path.append dir (Path.basic name)) code) code_files;
     File.write driver_path driver;
     compile compiler cmd;
     evaluate compiler (File.bash_path compiled_path)
   end
 
 
 (* driver for Scala *)
 
 val scalaN = "Scala"
 
-fun evaluate_in_scala ctxt (code_files, value_name) dir =
+fun evaluate_in_scala (_: Proof.context) (code_files, value_name) dir =
   let
     val generatedN = "Generated_Code"
     val driverN = "Driver.scala"
 
-    val code = #2 (the_single code_files);
     val code_path = Path.append dir (Path.basic (generatedN ^ ".scala"))
     val driver_path = Path.append dir (Path.basic driverN)
     val out_path = Path.append dir (Path.basic "out")
+
+    val code = #2 (the_single code_files);
     val driver = \<^verbatim>\<open>
 {
   val result = \<close> ^ value_name ^ \<^verbatim>\<open>(())
   val result_text =
     result.map(
       {
         case (true, _) => "True\n"
         case (false, None) => "False\n"
         case (false, Some(t)) => "False" + t(()) + "\n"
       }).mkString
   isabelle.File.write(
     isabelle.Path.explode(\<close> ^ quote (Path.implode (Path.expand out_path)) ^ \<^verbatim>\<open>),
     \<close> ^ quote start_markerN ^ \<^verbatim>\<open> + result_text + \<close> ^ quote end_markerN ^ \<^verbatim>\<open>)
 }\<close>
   in
-    if Config.get ctxt debug
-    then (File.write code_path code; File.write driver_path driver)
-    else ();
+    File.write code_path code;
+    File.write driver_path driver;
     Scala_Compiler.toplevel true (code ^ driver);
     File.read out_path
   end
 
 
 (* command setup *)
 
 val _ =
   Outer_Syntax.command \<^command_keyword>\<open>test_code\<close>
     "compile test cases to target languages, execute them and report results"
       (Scan.repeat1 Parse.prop -- (\<^keyword>\<open>in\<close> |-- Scan.repeat1 Parse.name)
         >> (fn (ts, targets) => Toplevel.keep (test_code_cmd ts targets o Toplevel.context_of)))
 
 val target_Scala = "Scala_eval"
 val target_Haskell = "Haskell_eval"
 
 val _ = Theory.setup
    (Code_Target.add_derived_target (target_Scala, [(Code_Scala.target, I)])
     #> Code_Target.add_derived_target (target_Haskell, [(Code_Haskell.target, I)]))
 
 val _ =
   Theory.setup (fold add_driver
     [(polymlN, (evaluate_in_polyml, Code_ML.target_SML)),
      (mltonN, (evaluate_in_mlton, Code_ML.target_SML)),
      (smlnjN, (evaluate_in_smlnj, Code_ML.target_SML)),
      (ocamlN, (evaluate_in_ocaml, Code_ML.target_OCaml)),
      (ghcN, (evaluate_in_ghc, target_Haskell)),
      (scalaN, (evaluate_in_scala, target_Scala))]
   #> fold (fn target => Value_Command.add_evaluator (Binding.name target, eval_term target) #> snd)
       [polymlN, mltonN, smlnjN, ocamlN, ghcN, scalaN])
 
 end