(*  Title:      Tools/code/code_haskell.ML

    ID:         $Id$

    Author:     Florian Haftmann, TU Muenchen

Serializer for Haskell.

*)

signature CODE_HASKELL =

sig

  val setup: theory -> theory

end;

structure Code_Haskell : CODE_HASKELL =

struct

val target = "Haskell";

open Basic_Code_Thingol;

open Code_Printer;

infixr 5 @@;

infixr 5 @|;

(** Haskell serializer **)

fun pr_haskell_bind pr_term =

  let

    fun pr_bind ((NONE, NONE), _) = str "_"

      | pr_bind ((SOME v, NONE), _) = str v

      | pr_bind ((NONE, SOME p), _) = p

      | pr_bind ((SOME v, SOME p), _) = brackets [str v, str "@", p];

  in gen_pr_bind pr_bind pr_term end;

fun pr_haskell_stmt syntax_class syntax_tyco syntax_const labelled_name

    init_syms deresolve is_cons contr_classparam_typs deriving_show =

  let

    val deresolve_base = NameSpace.base o deresolve;

    fun class_name class = case syntax_class class

     of NONE => deresolve class

      | SOME (class, _) => class;

    fun classparam_name class classparam = case syntax_class class

     of NONE => deresolve_base classparam

      | SOME (_, classparam_syntax) => case classparam_syntax classparam

         of NONE => (snd o dest_name) classparam

          | SOME classparam => classparam;

    fun pr_typcontext tyvars vs = case maps (fn (v, sort) => map (pair v) sort) vs

     of [] => []

      | classbinds => Pretty.enum "," "(" ")" (

          map (fn (v, class) =>

            str (class_name class ^ " " ^ lookup_var tyvars v)) classbinds)

          @@ str " => ";

    fun pr_typforall tyvars vs = case map fst vs

     of [] => []

      | vnames => str "forall " :: Pretty.breaks

          (map (str o lookup_var tyvars) vnames) @ str "." @@ Pretty.brk 1;

    fun pr_tycoexpr tyvars fxy (tyco, tys) =

      brackify fxy (str tyco :: map (pr_typ tyvars BR) tys)

    and pr_typ tyvars fxy (tycoexpr as tyco `%% tys) = (case syntax_tyco tyco

         of NONE => pr_tycoexpr tyvars fxy (deresolve tyco, tys)

          | SOME (i, pr) => pr (pr_typ tyvars) fxy tys)

      | pr_typ tyvars fxy (ITyVar v) = (str o lookup_var tyvars) v;

    fun pr_typdecl tyvars (vs, tycoexpr) =

      Pretty.block (pr_typcontext tyvars vs @| pr_tycoexpr tyvars NOBR tycoexpr);

    fun pr_typscheme tyvars (vs, ty) =

      Pretty.block (pr_typforall tyvars vs @ pr_typcontext tyvars vs @| pr_typ tyvars NOBR ty);

    fun pr_term tyvars thm pat vars fxy (IConst c) =

          pr_app tyvars thm pat vars fxy (c, [])

      | pr_term tyvars thm pat vars fxy (t as (t1 `$ t2)) =

          (case Code_Thingol.unfold_const_app t

           of SOME app => pr_app tyvars thm pat vars fxy app

            | _ =>

                brackify fxy [

                  pr_term tyvars thm pat vars NOBR t1,

                  pr_term tyvars thm pat vars BR t2

                ])

      | pr_term tyvars thm pat vars fxy (IVar v) =

          (str o lookup_var vars) v

      | pr_term tyvars thm pat vars fxy (t as _ `|-> _) =

          let

            val (binds, t') = Code_Thingol.unfold_abs t;

            fun pr ((v, pat), ty) = pr_bind tyvars thm BR ((SOME v, pat), ty);

            val (ps, vars') = fold_map pr binds vars;

          in brackets (str "\\" :: ps @ str "->" @@ pr_term tyvars thm pat vars' NOBR t') end

      | pr_term tyvars thm pat vars fxy (ICase (cases as (_, t0))) =

          (case Code_Thingol.unfold_const_app t0

           of SOME (c_ts as ((c, _), _)) => if is_none (syntax_const c)

                then pr_case tyvars thm vars fxy cases

                else pr_app tyvars thm pat vars fxy c_ts

            | NONE => pr_case tyvars thm vars fxy cases)

    and pr_app' tyvars thm pat vars ((c, (_, tys)), ts) = case contr_classparam_typs c

     of [] => (str o deresolve) c :: map (pr_term tyvars thm pat vars BR) ts

      | fingerprint => let

          val ts_fingerprint = ts ~~ curry Library.take (length ts) fingerprint;

          val needs_annotation = forall (fn (_, NONE) => true | (t, SOME _) =>

            (not o Code_Thingol.locally_monomorphic) t) ts_fingerprint;

          fun pr_term_anno (t, NONE) _ = pr_term tyvars thm pat vars BR t

            | pr_term_anno (t, SOME _) ty =

                brackets [pr_term tyvars thm pat vars NOBR t, str "::", pr_typ tyvars NOBR ty];

        in

          if needs_annotation then

            (str o deresolve) c :: map2 pr_term_anno ts_fingerprint (curry Library.take (length ts) tys)

          else (str o deresolve) c :: map (pr_term tyvars thm pat vars BR) ts

        end

    and pr_app tyvars = gen_pr_app (pr_app' tyvars) (pr_term tyvars) syntax_const is_cons

    and pr_bind tyvars = pr_haskell_bind (pr_term tyvars)

    and pr_case tyvars thm vars fxy (cases as ((_, [_]), _)) =

          let

            val (binds, t) = Code_Thingol.unfold_let (ICase cases);

            fun pr ((pat, ty), t) vars =

              vars

              |> pr_bind tyvars thm BR ((NONE, SOME pat), ty)

              |>> (fn p => semicolon [p, str "=", pr_term tyvars thm false vars NOBR t])

            val (ps, vars') = fold_map pr binds vars;

          in

            Pretty.block_enclose (

              str "let {",

              concat [str "}", str "in", pr_term tyvars thm false vars' NOBR t]

            ) ps

          end

      | pr_case tyvars thm vars fxy (((td, ty), bs as _ :: _), _) =

          let

            fun pr (pat, t) =

              let

                val (p, vars') = pr_bind tyvars thm NOBR ((NONE, SOME pat), ty) vars;

              in semicolon [p, str "->", pr_term tyvars thm false vars' NOBR t] end;

          in

            Pretty.block_enclose (

              concat [str "(case", pr_term tyvars thm false vars NOBR td, str "of", str "{"],

              str "})"

            ) (map pr bs)

          end

      | pr_case tyvars thm vars fxy ((_, []), _) = str "error \"empty case\"";

    fun pr_stmt (name, Code_Thingol.Fun ((vs, ty), [])) =

          let

            val tyvars = intro_vars (map fst vs) init_syms;

            val n = (length o fst o Code_Thingol.unfold_fun) ty;

          in

            Pretty.chunks [

              Pretty.block [

                (str o suffix " ::" o deresolve_base) name,

                Pretty.brk 1,

                pr_typscheme tyvars (vs, ty),

                str ";"

              ],

              concat (

                (str o deresolve_base) name

                :: map str (replicate n "_")

                @ str "="

                :: str "error"

                @@ (str o (fn s => s ^ ";") o ML_Syntax.print_string

                    o NameSpace.base o NameSpace.qualifier) name

              )

            ]

          end

      | pr_stmt (name, Code_Thingol.Fun ((vs, ty), eqs)) =

          let

            val tyvars = intro_vars (map fst vs) init_syms;

            fun pr_eq ((ts, t), thm) =

              let

                val consts = map_filter

                  (fn c => if (is_some o syntax_const) c

                    then NONE else (SOME o NameSpace.base o deresolve) c)

                    ((fold o Code_Thingol.fold_constnames) (insert (op =)) (t :: ts) []);

                val vars = init_syms

                  |> intro_vars consts

                  |> intro_vars ((fold o Code_Thingol.fold_unbound_varnames)

                       (insert (op =)) ts []);

              in

                semicolon (

                  (str o deresolve_base) name

                  :: map (pr_term tyvars thm true vars BR) ts

                  @ str "="

                  @@ pr_term tyvars thm false vars NOBR t

                )

              end;

          in

            Pretty.chunks (

              Pretty.block [

                (str o suffix " ::" o deresolve_base) name,

                Pretty.brk 1,

                pr_typscheme tyvars (vs, ty),

                str ";"

              ]

              :: map pr_eq eqs

            )

          end

      | pr_stmt (name, Code_Thingol.Datatype (vs, [])) =

          let

            val tyvars = intro_vars (map fst vs) init_syms;

          in

            semicolon [

              str "data",

              pr_typdecl tyvars (vs, (deresolve_base name, map (ITyVar o fst) vs))

            ]

          end

      | pr_stmt (name, Code_Thingol.Datatype (vs, [(co, [ty])])) =

          let

            val tyvars = intro_vars (map fst vs) init_syms;

          in

            semicolon (

              str "newtype"

              :: pr_typdecl tyvars (vs, (deresolve_base name, map (ITyVar o fst) vs))

              :: str "="

              :: (str o deresolve_base) co

              :: pr_typ tyvars BR ty

              :: (if deriving_show name then [str "deriving (Read, Show)"] else [])

            )

          end

      | pr_stmt (name, Code_Thingol.Datatype (vs, co :: cos)) =

          let

            val tyvars = intro_vars (map fst vs) init_syms;

            fun pr_co (co, tys) =

              concat (

                (str o deresolve_base) co

                :: map (pr_typ tyvars BR) tys

              )

          in

            semicolon (

              str "data"

              :: pr_typdecl tyvars (vs, (deresolve_base name, map (ITyVar o fst) vs))

              :: str "="

              :: pr_co co

              :: map ((fn p => Pretty.block [str "| ", p]) o pr_co) cos

              @ (if deriving_show name then [str "deriving (Read, Show)"] else [])

            )

          end

      | pr_stmt (name, Code_Thingol.Class (v, (superclasses, classparams))) =

          let

            val tyvars = intro_vars [v] init_syms;

            fun pr_classparam (classparam, ty) =

              semicolon [

                (str o classparam_name name) classparam,

                str "::",

                pr_typ tyvars NOBR ty

              ]

          in

            Pretty.block_enclose (

              Pretty.block [

                str "class ",

                Pretty.block (pr_typcontext tyvars [(v, map fst superclasses)]),

                str (deresolve_base name ^ " " ^ lookup_var tyvars v),

                str " where {"

              ],

              str "};"

            ) (map pr_classparam classparams)

          end

      | pr_stmt (_, Code_Thingol.Classinst ((class, (tyco, vs)), (_, classparam_insts))) =

          let

            val tyvars = intro_vars (map fst vs) init_syms;

            fun pr_instdef ((classparam, c_inst), thm) =

              semicolon [

                (str o classparam_name class) classparam,

                str "=",

                pr_app tyvars thm false init_syms NOBR (c_inst, [])

              ];

          in

            Pretty.block_enclose (

              Pretty.block [

                str "instance ",

                Pretty.block (pr_typcontext tyvars vs),

                str (class_name class ^ " "),

                pr_typ tyvars BR (tyco `%% map (ITyVar o fst) vs),

                str " where {"

              ],

              str "};"

            ) (map pr_instdef classparam_insts)

          end;

  in pr_stmt end;

fun haskell_program_of_program labelled_name module_name module_prefix reserved_names raw_module_alias program =

  let

    val module_alias = if is_some module_name then K module_name else raw_module_alias;

    val reserved_names = Name.make_context reserved_names;

    val mk_name_module = mk_name_module reserved_names module_prefix module_alias program;

    fun add_stmt (name, (stmt, deps)) =

      let

        val (module_name, base) = dest_name name;

        val module_name' = mk_name_module module_name;

        val mk_name_stmt = yield_singleton Name.variants;

        fun add_fun upper (nsp_fun, nsp_typ) =

          let

            val (base', nsp_fun') =

              mk_name_stmt (if upper then first_upper base else base) nsp_fun

          in (base', (nsp_fun', nsp_typ)) end;

        fun add_typ (nsp_fun, nsp_typ) =

          let

            val (base', nsp_typ') = mk_name_stmt (first_upper base) nsp_typ

          in (base', (nsp_fun, nsp_typ')) end;

        val add_name = case stmt

         of Code_Thingol.Fun _ => add_fun false

          | Code_Thingol.Datatype _ => add_typ

          | Code_Thingol.Datatypecons _ => add_fun true

          | Code_Thingol.Class _ => add_typ

          | Code_Thingol.Classrel _ => pair base

          | Code_Thingol.Classparam _ => add_fun false

          | Code_Thingol.Classinst _ => pair base;

        fun add_stmt' base' = case stmt

         of Code_Thingol.Datatypecons _ =>

              cons (name, (NameSpace.append module_name' base', NONE))

          | Code_Thingol.Classrel _ => I

          | Code_Thingol.Classparam _ =>

              cons (name, (NameSpace.append module_name' base', NONE))

          | _ => cons (name, (NameSpace.append module_name' base', SOME stmt));

      in

        Symtab.map_default (module_name', ([], ([], (reserved_names, reserved_names))))

              (apfst (fold (insert (op = : string * string -> bool)) deps))

        #> `(fn program => add_name ((snd o snd o the o Symtab.lookup program) module_name'))

        #-> (fn (base', names) =>

              (Symtab.map_entry module_name' o apsnd) (fn (stmts, _) =>

              (add_stmt' base' stmts, names)))

      end;

    val hs_program = fold add_stmt (AList.make (fn name =>

      (Graph.get_node program name, Graph.imm_succs program name))

      (Graph.strong_conn program |> flat)) Symtab.empty;

    fun deresolver name =

      (fst o the o AList.lookup (op =) ((fst o snd o the

        o Symtab.lookup hs_program) ((mk_name_module o fst o dest_name) name))) name

        handle Option => error ("Unknown statement name: " ^ labelled_name name);

  in (deresolver, hs_program) end;

fun serialize_haskell module_prefix raw_module_name string_classes labelled_name

    reserved_names includes raw_module_alias

    syntax_class syntax_tyco syntax_const program cs destination =

  let

    val stmt_names = Code_Target.stmt_names_of_destination destination;

    val module_name = if null stmt_names then raw_module_name else SOME "Code";

    val (deresolver, hs_program) = haskell_program_of_program labelled_name

      module_name module_prefix reserved_names raw_module_alias program;

    val is_cons = Code_Thingol.is_cons program;

    val contr_classparam_typs = Code_Thingol.contr_classparam_typs program;

    fun deriving_show tyco =

      let

        fun deriv _ "fun" = false

          | deriv tycos tyco = member (op =) tycos tyco orelse

              case try (Graph.get_node program) tyco

                of SOME (Code_Thingol.Datatype (_, cs)) => forall (deriv' (tyco :: tycos))

                    (maps snd cs)

                 | NONE => true

        and deriv' tycos (tyco `%% tys) = deriv tycos tyco

              andalso forall (deriv' tycos) tys

          | deriv' _ (ITyVar _) = true

      in deriv [] tyco end;

    val reserved_names = make_vars reserved_names;

    fun pr_stmt qualified = pr_haskell_stmt syntax_class syntax_tyco

      syntax_const labelled_name reserved_names

      (if qualified then deresolver else NameSpace.base o deresolver)

      is_cons contr_classparam_typs

      (if string_classes then deriving_show else K false);

    fun pr_module name content =

      (name, Pretty.chunks [

        str ("module " ^ name ^ " where {"),

        str "",

        content,

        str "",

        str "}"

      ]);

    fun serialize_module1 (module_name', (deps, (stmts, _))) =

      let

        val stmt_names = map fst stmts;

        val deps' = subtract (op =) stmt_names deps

          |> distinct (op =)

          |> map_filter (try deresolver);

        val qualified = is_none module_name andalso

          map deresolver stmt_names @ deps'

          |> map NameSpace.base

          |> has_duplicates (op =);

        val imports = deps'

          |> map NameSpace.qualifier

          |> distinct (op =);

        fun pr_import_include (name, _) = str ("import " ^ name ^ ";");

        val pr_import_module = str o (if qualified

          then prefix "import qualified "

          else prefix "import ") o suffix ";";

        val content = Pretty.chunks (

            map pr_import_include includes

            @ map pr_import_module imports

            @ str ""

            :: separate (str "") (map_filter

              (fn (name, (_, SOME stmt)) => SOME (pr_stmt qualified (name, stmt))

                | (_, (_, NONE)) => NONE) stmts)

          )

      in pr_module module_name' content end;

    fun serialize_module2 (_, (_, (stmts, _))) = Pretty.chunks (

      separate (str "") (map_filter

        (fn (name, (_, SOME stmt)) => if null stmt_names

              orelse member (op =) stmt_names name

              then SOME (pr_stmt false (name, stmt))

              else NONE

          | (_, (_, NONE)) => NONE) stmts));

    val serialize_module =

      if null stmt_names then serialize_module1 else pair "" o serialize_module2;

    fun write_module destination (modlname, content) =

      let

        val filename = case modlname

         of "" => Path.explode "Main.hs"

          | _ => (Path.ext "hs" o Path.explode o implode o separate "/"

                o NameSpace.explode) modlname;

        val pathname = Path.append destination filename;

        val _ = File.mkdir (Path.dir pathname);

      in File.write pathname (Code_Target.code_of_pretty content) end

  in

    Code_Target.mk_serialization target NONE

      (fn NONE => K () o map (Code_Target.code_writeln o snd) | SOME file => K () o map (write_module file))

      (rpair [] o cat_lines o map (Code_Target.code_of_pretty o snd))

      (map (uncurry pr_module) includes

        @ map serialize_module (Symtab.dest hs_program))

      destination

  end;

val literals = let

  fun char_haskell c =

    let

      val s = ML_Syntax.print_char c;

    in if s = "'" then "\\'" else s end;

in Literals {

  literal_char = enclose "'" "'" o char_haskell,

  literal_string = quote o translate_string char_haskell,

  literal_numeral = fn unbounded => fn k => if k >= 0 then string_of_int k

    else enclose "(" ")" (signed_string_of_int k),

  literal_list = Pretty.enum "," "[" "]",

  infix_cons = (5, ":")

} end;

(** optional monad syntax **)

fun implode_monad c_bind t =

  let

    fun dest_monad (IConst (c, _) `$ t1 `$ t2) =

          if c = c_bind

            then case Code_Thingol.split_abs t2

             of SOME (((v, pat), ty), t') =>

                  SOME ((SOME (((SOME v, pat), ty), true), t1), t')

              | NONE => NONE

            else NONE

      | dest_monad t = case Code_Thingol.split_let t

           of SOME (((pat, ty), tbind), t') =>

                SOME ((SOME (((NONE, SOME pat), ty), false), tbind), t')

            | NONE => NONE;

  in Code_Thingol.unfoldr dest_monad t end;

fun pretty_haskell_monad c_bind =

  let

    fun pretty pr thm pat vars fxy [(t, _)] =

      let

        val pr_bind = pr_haskell_bind (K (K pr)) thm;

        fun pr_monad (NONE, t) vars =

              (semicolon [pr vars NOBR t], vars)

          | pr_monad (SOME (bind, true), t) vars = vars

              |> pr_bind NOBR bind

              |>> (fn p => semicolon [p, str "<-", pr vars NOBR t])

          | pr_monad (SOME (bind, false), t) vars = vars

              |> pr_bind NOBR bind

              |>> (fn p => semicolon [str "let", p, str "=", pr vars NOBR t]);

        val (binds, t) = implode_monad c_bind t;

        val (ps, vars') = fold_map pr_monad binds vars;

      in (brackify fxy o single o Pretty.enclose "do {" "}") (ps @| pr vars' NOBR t) end;

  in (1, pretty) end;

fun add_monad target' raw_c_run raw_c_bind thy =

  let

    val c_run = Code_Unit.read_const thy raw_c_run;

    val c_bind = Code_Unit.read_const thy raw_c_bind;

    val c_bind' = Code_Name.const thy c_bind;

  in if target = target' then

    thy

    |> Code_Target.add_syntax_const target c_run

        (SOME (pretty_haskell_monad c_bind'))

    |> Code_Target.add_syntax_const target c_bind

        (Code_Printer.simple_const_syntax (SOME (Code_Printer.parse_infix fst (L, 1) ">>=")))

  else error "Only Haskell target allows for monad syntax" end;

(** Isar setup **)

fun isar_seri_haskell module =

  Code_Target.parse_args (Scan.option (Args.$$$ "root" -- Args.colon |-- Args.name)

    -- Scan.optional (Args.$$$ "string_classes" >> K true) false

    >> (fn (module_prefix, string_classes) =>

      serialize_haskell module_prefix module string_classes));

val _ =

  OuterSyntax.command "code_monad" "define code syntax for monads" OuterKeyword.thy_decl (

    OuterParse.term_group -- OuterParse.term_group -- OuterParse.name

    >> (fn ((raw_run, raw_bind), target) => Toplevel.theory 

          (add_monad target raw_run raw_bind))

  );

val setup =

  Code_Target.add_target (target, (isar_seri_haskell, literals))

  #> Code_Target.add_syntax_tyco target "fun" (SOME (2, fn pr_typ => fn fxy => fn [ty1, ty2] =>

      brackify_infix (1, R) fxy [

        pr_typ (INFX (1, X)) ty1,

        str "->",

        pr_typ (INFX (1, R)) ty2

      ]))

  #> fold (Code_Target.add_reserved target) [

      "hiding", "deriving", "where", "case", "of", "infix", "infixl", "infixr",

      "import", "default", "forall", "let", "in", "class", "qualified", "data",

      "newtype", "instance", "if", "then", "else", "type", "as", "do", "module"

    ]

  #> fold (Code_Target.add_reserved target) [

      "Prelude", "Main", "Bool", "Maybe", "Either", "Ordering", "Char", "String", "Int",

      "Integer", "Float", "Double", "Rational", "IO", "Eq", "Ord", "Enum", "Bounded",

      "Num", "Real", "Integral", "Fractional", "Floating", "RealFloat", "Monad", "Functor",

      "AlreadyExists", "ArithException", "ArrayException", "AssertionFailed", "AsyncException",

      "BlockedOnDeadMVar", "Deadlock", "Denormal", "DivideByZero", "DotNetException", "DynException",

      "Dynamic", "EOF", "EQ", "EmptyRec", "ErrorCall", "ExitException", "ExitFailure",

      "ExitSuccess", "False", "GT", "HeapOverflow",

      "IOError", "IOException", "IllegalOperation",

      "IndexOutOfBounds", "Just", "Key", "LT", "Left", "LossOfPrecision", "NoMethodError",

      "NoSuchThing", "NonTermination", "Nothing", "Obj", "OtherError", "Overflow",

      "PatternMatchFail", "PermissionDenied", "ProtocolError", "RecConError", "RecSelError",

      "RecUpdError", "ResourceBusy", "ResourceExhausted", "Right", "StackOverflow",

      "ThreadKilled", "True", "TyCon", "TypeRep", "UndefinedElement", "Underflow",

      "UnsupportedOperation", "UserError", "abs", "absReal", "acos", "acosh", "all",

      "and", "any", "appendFile", "asTypeOf", "asciiTab", "asin", "asinh", "atan",

      "atan2", "atanh", "basicIORun", "blockIO", "boundedEnumFrom", "boundedEnumFromThen",

      "boundedEnumFromThenTo", "boundedEnumFromTo", "boundedPred", "boundedSucc", "break",

      "catch", "catchException", "ceiling", "compare", "concat", "concatMap", "const",

      "cos", "cosh", "curry", "cycle", "decodeFloat", "denominator", "div", "divMod",

      "doubleToRatio", "doubleToRational", "drop", "dropWhile", "either", "elem",

      "emptyRec", "encodeFloat", "enumFrom", "enumFromThen", "enumFromThenTo",

      "enumFromTo", "error", "even", "exp", "exponent", "fail", "filter", "flip",

      "floatDigits", "floatProperFraction", "floatRadix", "floatRange", "floatToRational",

      "floor", "fmap", "foldl", "foldl'", "foldl1", "foldr", "foldr1", "fromDouble",

      "fromEnum", "fromEnum_0", "fromInt", "fromInteger", "fromIntegral", "fromObj",

      "fromRational", "fst", "gcd", "getChar", "getContents", "getLine", "head",

      "id", "inRange", "index", "init", "intToRatio", "interact", "ioError", "isAlpha",

      "isAlphaNum", "isDenormalized", "isDigit", "isHexDigit", "isIEEE", "isInfinite",

      "isLower", "isNaN", "isNegativeZero", "isOctDigit", "isSpace", "isUpper", "iterate", "iterate'",

      "last", "lcm", "length", "lex", "lexDigits", "lexLitChar", "lexmatch", "lines", "log",

      "logBase", "lookup", "loop", "map", "mapM", "mapM_", "max", "maxBound", "maximum",

      "maybe", "min", "minBound", "minimum", "mod", "negate", "nonnull", "not", "notElem",

      "null", "numerator", "numericEnumFrom", "numericEnumFromThen", "numericEnumFromThenTo",

      "numericEnumFromTo", "odd", "or", "otherwise", "pi", "pred", 

      "print", "product", "properFraction", "protectEsc", "putChar", "putStr", "putStrLn",

      "quot", "quotRem", "range", "rangeSize", "rationalToDouble", "rationalToFloat",

      "rationalToRealFloat", "read", "readDec", "readField", "readFieldName", "readFile",

      "readFloat", "readHex", "readIO", "readInt", "readList", "readLitChar", "readLn",

      "readOct", "readParen", "readSigned", "reads", "readsPrec", "realFloatToRational",

      "realToFrac", "recip", "reduce", "rem", "repeat", "replicate", "return", "reverse",

      "round", "scaleFloat", "scanl", "scanl1", "scanr", "scanr1", "seq", "sequence",

      "sequence_", "show", "showChar", "showException", "showField", "showList",

      "showLitChar", "showParen", "showString", "shows", "showsPrec", "significand",

      "signum", "signumReal", "sin", "sinh", "snd", "span", "splitAt", "sqrt", "subtract",

      "succ", "sum", "tail", "take", "takeWhile", "takeWhile1", "tan", "tanh", "threadToIOResult",

      "throw", "toEnum", "toInt", "toInteger", "toObj", "toRational", "truncate", "uncurry",

      "undefined", "unlines", "unsafeCoerce", "unsafeIndex", "unsafeRangeSize", "until", "unwords",

      "unzip", "unzip3", "userError", "words", "writeFile", "zip", "zip3", "zipWith", "zipWith3"

    ] (*due to weird handling of ':', we can't do anything else than to import *all* prelude symbols*);

end; (*struct*)