src/Pure/variable.ML
author wenzelm
Sat Jun 17 19:37:52 2006 +0200 (2006-06-17)
changeset 19911 300bc6ce970d
parent 19899 b7385ca02d79
child 19926 feb4d150cfd8
permissions -rw-r--r--
major reworking of export functionality -- based on Term/Thm.generalize;
tuned interfaces;
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(*  Title:      Pure/variable.ML
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    ID:         $Id$
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    Author:     Makarius
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Fixed type/term variables and polymorphic term abbreviations.
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*)
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signature VARIABLE =
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sig
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  val is_body: Context.proof -> bool
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  val set_body: bool -> Context.proof -> Context.proof
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  val restore_body: Context.proof -> Context.proof -> Context.proof
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  val fixes_of: Context.proof -> (string * string) list
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  val fixed_names_of: Context.proof -> string list
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  val binds_of: Context.proof -> (typ * term) Vartab.table
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  val defaults_of: Context.proof ->
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    typ Vartab.table * sort Vartab.table * string list * string list Symtab.table
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  val used_types: Context.proof -> string list
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  val is_declared: Context.proof -> string -> bool
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  val is_fixed: Context.proof -> string -> bool
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  val def_sort: Context.proof -> indexname -> sort option
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  val def_type: Context.proof -> bool -> indexname -> typ option
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  val default_type: Context.proof -> string -> typ option
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  val declare_type: typ -> Context.proof -> Context.proof
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  val declare_syntax: term -> Context.proof -> Context.proof
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  val declare_term: term -> Context.proof -> Context.proof
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  val rename_wrt: Context.proof -> term list -> (string * 'a) list -> (string * 'a) list
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  val add_fixes: string list -> Context.proof -> string list * Context.proof
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  val invent_fixes: string list -> Context.proof -> string list * Context.proof
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  val invent_types: sort list -> Context.proof -> (string * sort) list * Context.proof
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  val export_inst: Context.proof -> Context.proof -> string list * string list
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  val exportT_inst: Context.proof -> Context.proof -> string list
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  val export_terms: Context.proof -> Context.proof -> term list -> term list
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  val exportT_terms: Context.proof -> Context.proof -> term list -> term list
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  val exportT: Context.proof -> Context.proof -> thm list -> thm list
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  val export: Context.proof -> Context.proof -> thm list -> thm list
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  val importT_inst: term list -> Context.proof -> ((indexname * sort) * typ) list * Context.proof
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  val import_inst: bool -> term list -> Context.proof ->
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    (((indexname * sort) * typ) list * ((indexname * typ) * term) list) * Context.proof
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  val importT_terms: term list -> Context.proof -> term list * Context.proof
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  val import_terms: bool -> term list -> Context.proof -> term list * Context.proof
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  val importT: thm list -> Context.proof -> thm list * Context.proof
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  val import: bool -> thm list -> Context.proof -> thm list * Context.proof
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  val warn_extra_tfrees: Context.proof -> Context.proof -> unit
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  val monomorphic: Context.proof -> term list -> term list
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  val polymorphic: Context.proof -> term list -> term list
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  val hidden_polymorphism: term -> typ -> (indexname * sort) list
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  val add_binds: (indexname * term option) list -> Context.proof -> Context.proof
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  val expand_binds: Context.proof -> term -> term
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end;
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structure Variable: VARIABLE =
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struct
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(** local context data **)
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datatype data = Data of
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 {is_body: bool,                          (*inner body mode*)
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  fixes: (string * string) list,          (*term fixes -- extern/intern*)
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  binds: (typ * term) Vartab.table,       (*term bindings*)
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  defaults:
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    typ Vartab.table *                    (*type constraints*)
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    sort Vartab.table *                   (*default sorts*)
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    string list *                         (*used type variables*)
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    string list Symtab.table};            (*occurrences of type variables in term variables*)
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fun make_data (is_body, fixes, binds, defaults) =
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  Data {is_body = is_body, fixes = fixes, binds = binds, defaults = defaults};
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structure Data = ProofDataFun
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(
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  val name = "Pure/variable";
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  type T = data;
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  fun init thy =
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    make_data (false, [], Vartab.empty, (Vartab.empty, Vartab.empty, [], Symtab.empty));
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  fun print _ _ = ();
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);
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val _ = Context.add_setup Data.init;
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fun map_data f =
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  Data.map (fn Data {is_body, fixes, binds, defaults} =>
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    make_data (f (is_body, fixes, binds, defaults)));
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fun map_fixes f = map_data (fn (is_body, fixes, binds, defaults) =>
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  (is_body, f fixes, binds, defaults));
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fun map_binds f = map_data (fn (is_body, fixes, binds, defaults) =>
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  (is_body, fixes, f binds, defaults));
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fun map_defaults f = map_data (fn (is_body, fixes, binds, defaults) =>
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  (is_body, fixes, binds, f defaults));
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fun rep_data ctxt = Data.get ctxt |> (fn Data args => args);
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val is_body = #is_body o rep_data;
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fun set_body b = map_data (fn (_, fixes, binds, defaults) => (b, fixes, binds, defaults));
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fun restore_body ctxt = set_body (is_body ctxt);
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val fixes_of = #fixes o rep_data;
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val fixed_names_of = map #2 o fixes_of;
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val binds_of = #binds o rep_data;
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val defaults_of = #defaults o rep_data;
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val used_types = #3 o defaults_of;
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val type_occs_of = #4 o defaults_of;
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fun is_declared ctxt x = Vartab.defined (#1 (defaults_of ctxt)) (x, ~1);
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fun is_fixed ctxt x = exists (fn (_, y) => x = y) (fixes_of ctxt);
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(** declarations **)
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(* default sorts and types *)
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val def_sort = Vartab.lookup o #2 o defaults_of;
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fun def_type ctxt pattern xi =
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  let val {binds, defaults = (types, _, _, _), ...} = rep_data ctxt in
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    (case Vartab.lookup types xi of
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      NONE =>
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        if pattern then NONE
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        else Vartab.lookup binds xi |> Option.map (TypeInfer.polymorphicT o #1)
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    | some => some)
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  end;
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fun default_type ctxt x = Vartab.lookup (#1 (defaults_of ctxt)) (x, ~1);
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(* declare types/terms *)
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local
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val ins_types = fold_aterms
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  (fn Free (x, T) => Vartab.update ((x, ~1), T)
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    | Var v => Vartab.update v
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    | _ => I);
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val ins_sorts = fold_atyps
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  (fn TFree (x, S) => Vartab.update ((x, ~1), S)
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    | TVar v => Vartab.update v
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    | _ => I);
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val ins_used = fold_atyps
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  (fn TFree (x, _) => insert (op =) x | _ => I);
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val ins_occs = fold_term_types (fn t =>
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  let val x = case t of Free (x, _) => x | _ => ""
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  in fold_atyps (fn TFree (a, _) => Symtab.insert_list (op =) (a, x) | _ => I) end);
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fun ins_skolem def_ty = fold_rev (fn (x, x') =>
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  (case def_ty x' of
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    SOME T => Vartab.update ((x, ~1), T)
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  | NONE => I));
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in
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fun declare_type T = map_defaults (fn (types, sorts, used, occ) =>
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 (types,
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  ins_sorts T sorts,
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  ins_used T used,
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  occ));
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fun declare_syntax t = map_defaults (fn (types, sorts, used, occ) =>
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 (ins_types t types,
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  fold_types ins_sorts t sorts,
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  fold_types ins_used t used,
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  occ));
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fun declare_occs t = map_defaults (fn (types, sorts, used, occ) =>
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  (types, sorts, used, ins_occs t occ));
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fun declare_term t ctxt =
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  ctxt
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  |> declare_syntax t
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  |> map_defaults (fn (types, sorts, used, occ) =>
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     (ins_skolem (fn x => Vartab.lookup types (x, ~1)) (fixes_of ctxt) types,
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      sorts,
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      used,
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      ins_occs t occ));
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end;
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(* renaming term/type frees *)
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fun rename_wrt ctxt ts frees =
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  let
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    val (types, sorts, _, _) = defaults_of (ctxt |> fold declare_syntax ts);
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    fun ren (x, X) xs =
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      let
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        fun used y = y = "" orelse y = "'" orelse member (op =) xs y orelse
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          Vartab.defined types (y, ~1) orelse Vartab.defined sorts (y, ~1);
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        val x' = Term.variant_name used x;
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      in ((x', X), x' :: xs) end;
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  in #1 (fold_map ren frees []) end;
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(** fixes **)
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fun no_dups [] = ()
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  | no_dups dups = error ("Duplicate fixed variable(s): " ^ commas_quote dups);
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fun add_fixes xs ctxt =
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  let
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    val (ys, zs) = split_list (fixes_of ctxt);
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    val _ = no_dups (duplicates (op =) xs);
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    val _ =
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      (case filter (can Term.dest_skolem) xs of [] => ()
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      | bads => error ("Illegal internal Skolem constant(s): " ^ commas_quote bads));
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    val xs' =
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      if is_body ctxt then Term.variantlist (map Term.skolem xs, zs)
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      else (no_dups (xs inter_string ys); no_dups (xs inter_string zs); xs);
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  in
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    ctxt
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    |> map_fixes (fn fixes => rev (xs ~~ xs') @ fixes)
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    |> fold (declare_syntax o Syntax.free) xs'
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    |> pair xs'
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  end;
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fun invent_fixes xs ctxt =
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  ctxt
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  |> set_body true
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  |> add_fixes (Term.variantlist (xs, []))
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  ||> restore_body ctxt;
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fun invent_types Ss ctxt =
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  let
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    val tfrees = Term.invent_names (used_types ctxt) "'a" (length Ss) ~~ Ss;
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    val ctxt' = fold (declare_type o TFree) tfrees ctxt;
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  in (tfrees, ctxt') end;
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(** export -- generalize type/term variables **)
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fun export_inst inner outer =
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  let
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    val types_outer = used_types outer;
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    val fixes_inner = fixes_of inner;
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    val fixes_outer = fixes_of outer;
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    val gen_fixes = map #2 (Library.take (length fixes_inner - length fixes_outer, fixes_inner));
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    val still_fixed = not o member (op =) ("" :: gen_fixes);
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    val gen_fixesT =
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      Symtab.fold (fn (a, xs) =>
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        if member (op =) types_outer a orelse exists still_fixed xs
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        then I else cons a) (type_occs_of inner) [];
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  in (gen_fixesT, gen_fixes) end;
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fun exportT_inst inner outer = #1 (export_inst inner outer);
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fun exportT_terms inner outer ts =
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  map (Term.generalize (exportT_inst (fold declare_occs ts inner) outer, [])
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    (fold (Term.fold_types Term.maxidx_typ) ts ~1 + 1)) ts;
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fun export_terms inner outer ts =
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  map (Term.generalize (export_inst (fold declare_occs ts inner) outer)
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    (fold Term.maxidx_term ts ~1 + 1)) ts;
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fun gen_export inst inner outer ths =
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  let
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    val maxidx = fold Thm.maxidx_thm ths ~1;
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    val inner' = fold (declare_occs o Thm.full_prop_of) ths inner;
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  in map (Thm.generalize (inst inner' outer) (maxidx + 1)) ths end;
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val exportT = gen_export (rpair [] oo exportT_inst);
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val export = gen_export export_inst;
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(** import -- fix schematic type/term variables **)
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fun importT_inst ts ctxt =
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  let
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    val tvars = rev (fold Term.add_tvars ts []);
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    val (tfrees, ctxt') = invent_types (map #2 tvars) ctxt;
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  in (tvars ~~ map TFree tfrees, ctxt') end;
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fun import_inst is_open ts ctxt =
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  let
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    val (instT, ctxt') = importT_inst ts ctxt;
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    val vars = map (apsnd (Term.instantiateT instT)) (rev (fold Term.add_vars ts []));
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    val ren = if is_open then I else Term.internal;
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    val (xs, ctxt'') = invent_fixes (map (ren o #1 o #1) vars) ctxt';
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    val inst = vars ~~ map Free (xs ~~ map #2 vars);
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  in ((instT, inst), ctxt'') end;
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fun importT_terms ts ctxt =
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  let val (instT, ctxt') = importT_inst ts ctxt
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  in (map (Term.instantiate (instT, [])) ts, ctxt') end;
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fun import_terms is_open ts ctxt =
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  let val (inst, ctxt') = import_inst is_open ts ctxt
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  in (map (Term.instantiate inst) ts, ctxt') end;
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fun importT ths ctxt =
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  let
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    val thy = Context.theory_of_proof ctxt;
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    val certT = Thm.ctyp_of thy;
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    val (instT, ctxt') = importT_inst (map Thm.full_prop_of ths) ctxt;
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    val instT' = map (fn (v, T) => (certT (TVar v), certT T)) instT;
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    val ths' = map (Thm.instantiate (instT', [])) ths;
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  in (ths', ctxt') end;
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fun import is_open ths ctxt =
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  let
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    val thy = Context.theory_of_proof ctxt;
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    val cert = Thm.cterm_of thy;
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    val certT = Thm.ctyp_of thy;
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    val ((instT, inst), ctxt') = import_inst is_open (map Thm.full_prop_of ths) ctxt;
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    val instT' = map (fn (v, T) => (certT (TVar v), certT T)) instT;
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    val inst' = map (fn (v, t) => (cert (Var v), cert t)) inst;
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    val ths' = map (Thm.instantiate (instT', inst')) ths;
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  in (ths', ctxt') end;
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(** implicit polymorphism **)
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(* warn_extra_tfrees *)
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fun warn_extra_tfrees ctxt1 ctxt2 =
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  let
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    fun occs_typ a = Term.exists_subtype (fn TFree (b, _) => a = b | _ => false);
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    fun occs_free _ "" = I
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      | occs_free a x =
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          (case def_type ctxt1 false (x, ~1) of
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            SOME T => if occs_typ a T then I else cons (a, x)
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          | NONE => cons (a, x));
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    val occs1 = type_occs_of ctxt1 and occs2 = type_occs_of ctxt2;
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    val extras = Symtab.fold (fn (a, xs) =>
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      if Symtab.defined occs1 a then I else fold (occs_free a) xs) occs2 [];
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    val tfrees = map #1 extras |> sort_distinct string_ord;
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    val frees = map #2 extras |> sort_distinct string_ord;
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  in
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    if null extras then ()
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    else warning ("Introduced fixed type variable(s): " ^ commas tfrees ^ " in " ^
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      space_implode " or " (map quote frees))
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  end;
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(* monomorphic vs. polymorphic terms *)
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fun monomorphic ctxt ts =
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  #1 (importT_terms ts (fold declare_term ts ctxt));
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fun polymorphic ctxt ts =
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  exportT_terms (fold declare_term ts ctxt) ctxt ts;
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(** term bindings **)
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fun hidden_polymorphism t T =
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  let
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    val tvarsT = Term.add_tvarsT T [];
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    val extra_tvars = Term.fold_types (Term.fold_atyps
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      (fn TVar v => if member (op =) tvarsT v then I else insert (op =) v | _ => I)) t [];
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  in extra_tvars end;
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fun add_bind (xi, NONE) = map_binds (Vartab.delete_safe xi)
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  | add_bind ((x, i), SOME t) =
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      let
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        val T = Term.fastype_of t;
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        val t' =
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          if null (hidden_polymorphism t T) then t
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          else Var ((x ^ "_has_extra_type_vars_on_rhs", i), T);
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      in declare_term t' #> map_binds (Vartab.update ((x, i), (T, t'))) end;
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val add_binds = fold add_bind;
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fun expand_binds ctxt =
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  let
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    val binds = binds_of ctxt;
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    fun expand (t as Var (xi, T)) =
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          (case Vartab.lookup binds xi of
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            SOME u => Envir.expand_atom T u
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          | NONE => t)
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      | expand t = t;
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  in Envir.beta_norm o Term.map_aterms expand end;
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end;