(*  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 naming labelled_name syntax_class syntax_tyco syntax_const

     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 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 ^ " " ^ Code_Name.lookup_var tyvars v)) classbinds)

           @@ str " => ";

     fun pr_typforall tyvars vs = case map fst vs

      of [] => []

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

           (map (str o Code_Name.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 Code_Name.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 vars fxy (IConst c) =

           pr_app tyvars thm vars fxy (c, [])

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

           (case Code_Thingol.unfold_const_app t

            of SOME app => pr_app tyvars thm vars fxy app

             | _ =>

                 brackify fxy [

                   pr_term tyvars thm vars NOBR t1,

                   pr_term tyvars thm vars BR t2

                 ])

       | pr_term tyvars thm vars fxy (IVar v) =

           (str o Code_Name.lookup_var vars) v

       | pr_term tyvars thm 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 vars' NOBR t') end

       | pr_term tyvars thm 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 vars fxy c_ts

             | NONE => pr_case tyvars thm vars fxy cases)

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

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

             | pr_term_anno (t, SOME _) ty =

                 brackets [pr_term tyvars thm 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 vars BR) ts

         end

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

     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 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 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 vars' NOBR t] end;

           in

             Pretty.block_enclose (

               concat [str "(case", pr_term tyvars thm 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 = Code_Name.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), raw_eqs))) =

           let

             val eqs = filter (snd o snd) raw_eqs;

             val tyvars = Code_Name.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

                   |> Code_Name.intro_vars consts

                   |> Code_Name.intro_vars ((fold o Code_Thingol.fold_unbound_varnames)

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

               in

                 semicolon (

                   (str o deresolve_base) name

                   :: map (pr_term tyvars thm vars BR) ts

                   @ str "="

                   @@ pr_term tyvars thm 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 = Code_Name.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 = Code_Name.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 = Code_Name.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 = Code_Name.intro_vars [v] init_syms;

             fun pr_classparam (classparam, ty) =

               semicolon [

                 (str o deresolve_base) 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 ^ " " ^ Code_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 split_abs_pure = (fn (v, _) `|-> t => SOME (v, t) | _ => NONE);

             val unfold_abs_pure = Code_Thingol.unfoldr split_abs_pure;

             val tyvars = Code_Name.intro_vars (map fst vs) init_syms;

             fun pr_instdef ((classparam, c_inst), (thm, _)) = case syntax_const classparam

              of NONE => semicolon [

                     (str o deresolve_base) classparam,

                     str "=",

                     pr_app tyvars thm init_syms NOBR (c_inst, [])

                   ]

               | SOME (k, pr) =>

                   let

                     val (c_inst_name, (_, tys)) = c_inst;

                     val const = if (is_some o syntax_const) c_inst_name

                       then NONE else (SOME o NameSpace.base o deresolve) c_inst_name;

                     val proto_rhs = Code_Thingol.eta_expand k (c_inst, []);

                     val (vs, rhs) = unfold_abs_pure proto_rhs;

                     val vars = init_syms

                       |> Code_Name.intro_vars (the_list const)

                       |> Code_Name.intro_vars vs;

                     val lhs = IConst (classparam, ([], tys)) `$$ map IVar vs;

                       (*dictionaries are not relevant at this late stage*)

                   in

                     semicolon [

                       pr_term tyvars thm vars NOBR lhs,

                       str "=",

                       pr_term tyvars thm vars NOBR rhs

                     ]

                   end;

           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 = Code_Name.mk_name_module reserved_names module_prefix module_alias program;

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

       let

         val (module_name, base) = Code_Name.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 Code_Name.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 (Code_Name.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 Code_Name.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 naming 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 = Code_Name.make_vars reserved_names;

     fun pr_stmt qualified = pr_haskell_stmt naming labelled_name

       syntax_class syntax_tyco syntax_const 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

         ("{-# OPTIONS_GHC -fglasgow-exts #-}\n\n"

           ^ 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 pretty_haskell_monad c_bind =

   let

     fun dest_bind t1 t2 = case Code_Thingol.split_abs t2

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

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

       | NONE => NONE;

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

           if c = c_bind_name then dest_bind t1 t2

           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;

     fun implode_monad c_bind_name = Code_Thingol.unfoldr (dest_monad c_bind_name);

     fun pr_monad pr_bind pr (NONE, t) vars =

           (semicolon [pr vars NOBR t], vars)

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

           |> pr_bind NOBR bind

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

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

           |> pr_bind NOBR bind

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

     fun pretty pr naming thm vars fxy [(t1, _), (t2, _)] = case dest_bind t1 t2

      of SOME (bind, t') => let

           val (binds, t'') = implode_monad ((the o Code_Thingol.lookup_const naming) c_bind) t'

           val (ps, vars') = fold_map (pr_monad (pr_haskell_bind (K pr) thm) pr) (bind :: binds) vars;

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

       | NONE => brackify_infix (1, L) fxy

           [pr vars (INFX (1, L)) t1, str ">>=", pr vars (INFX (1, X)) t2]

   in (2, pretty) end;

 fun add_monad target' raw_c_bind thy =

   let

     val c_bind = Code_Unit.read_const thy raw_c_bind;

   in if target = target' then

     thy

     |> Code_Target.add_syntax_const target c_bind

         (SOME (pretty_haskell_monad c_bind))

   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.name >> (fn (raw_bind, target) =>

       Toplevel.theory  (add_monad target 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*)