src/Pure/variable.ML
author wenzelm
Sun Jul 30 21:28:55 2006 +0200 (2006-07-30)
changeset 20262 ef3ee6a91c18
parent 20251 6379135f21c2
child 20303 e25d5a2a50bc
permissions -rw-r--r--
export: refrain from adjusting maxidx;
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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 names_of: Context.proof -> Name.context
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  val fixes_of: Context.proof -> (string * string) list
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  val binds_of: Context.proof -> (typ * term) Vartab.table
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  val constraints_of: Context.proof -> typ Vartab.table * sort Vartab.table
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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 newly_fixed: Context.proof -> Context.proof -> string -> bool
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  val default_type: Context.proof -> string -> typ option
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  val def_type: Context.proof -> bool -> indexname -> typ option
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  val def_sort: Context.proof -> indexname -> sort option
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  val declare_constraints: term -> Context.proof -> Context.proof
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  val declare_internal: term -> Context.proof -> Context.proof
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  val declare_term: term -> Context.proof -> Context.proof
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  val declare_thm: thm -> Context.proof -> Context.proof
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  val thm_context: thm -> Context.proof
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  val variant_frees: 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 add_fixes_direct: string list -> Context.proof -> Context.proof
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  val fix_frees: term -> Context.proof -> 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 -> (ctyp list * thm list) * Context.proof
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  val import: bool -> thm list -> Context.proof ->
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    ((ctyp list * cterm list) * thm list) * Context.proof
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  val tradeT: Context.proof -> (thm list -> thm list) -> thm list -> thm list
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  val trade: Context.proof -> (thm list -> thm list) -> thm list -> thm list
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  val focus: cterm -> Context.proof -> (cterm list * cterm) * Context.proof
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  val warn_extra_tfrees: Context.proof -> Context.proof -> unit
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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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  names: Name.context,                  (*type/term variable names*)
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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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  type_occs: string list Symtab.table,  (*type variables -- possibly within term variables*)
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  constraints:
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    typ Vartab.table *                  (*type constraints*)
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    sort Vartab.table};                 (*default sorts*)
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fun make_data (is_body, names, fixes, binds, type_occs, constraints) =
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  Data {is_body = is_body, names = names, fixes = fixes, binds = binds,
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    type_occs = type_occs, constraints = constraints};
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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, Name.context, [], Vartab.empty, Symtab.empty, (Vartab.empty, Vartab.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, names, fixes, binds, type_occs, constraints} =>
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    make_data (f (is_body, names, fixes, binds, type_occs, constraints)));
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fun map_names f = map_data (fn (is_body, names, fixes, binds, type_occs, constraints) =>
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  (is_body, f names, fixes, binds, type_occs, constraints));
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fun map_fixes f = map_data (fn (is_body, names, fixes, binds, type_occs, constraints) =>
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  (is_body, names, f fixes, binds, type_occs, constraints));
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fun map_binds f = map_data (fn (is_body, names, fixes, binds, type_occs, constraints) =>
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  (is_body, names, fixes, f binds, type_occs, constraints));
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fun map_type_occs f = map_data (fn (is_body, names, fixes, binds, type_occs, constraints) =>
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  (is_body, names, fixes, binds, f type_occs, constraints));
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fun map_constraints f = map_data (fn (is_body, names, fixes, binds, type_occs, constraints) =>
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  (is_body, names, fixes, binds, type_occs, f constraints));
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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 (_, names, fixes, binds, type_occs, constraints) =>
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  (b, names, fixes, binds, type_occs, constraints));
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fun restore_body ctxt = set_body (is_body ctxt);
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val names_of = #names o rep_data;
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val fixes_of = #fixes o rep_data;
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val binds_of = #binds o rep_data;
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val type_occs_of = #type_occs o rep_data;
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val constraints_of = #constraints o rep_data;
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val is_declared = Name.is_declared o names_of;
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fun is_fixed ctxt x = exists (fn (_, y) => x = y) (fixes_of ctxt);
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fun newly_fixed inner outer x = is_fixed inner x andalso not (is_fixed outer x);
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(** declarations **)
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(* default sorts and types *)
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fun default_type ctxt x = Vartab.lookup (#1 (constraints_of ctxt)) (x, ~1);
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fun def_type ctxt pattern xi =
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  let val {binds, constraints = (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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val def_sort = Vartab.lookup o #2 o constraints_of;
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(* names *)
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val declare_type_names = map_names o
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  fold_types (fold_atyps (fn TFree (a, _) => Name.declare a | _ => I));
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fun declare_names t =
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  declare_type_names t #>
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  map_names (fold_aterms (fn Free (x, _) => Name.declare x | _ => I) t);
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(* type occurrences *)
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val declare_type_occs = map_type_occs o fold_term_types
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  (fn Free (x, _) => fold_atyps (fn TFree (a, _) => Symtab.insert_list (op =) (a, x) | _ => I)
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    | _ => fold_atyps (fn TFree (a, _) => Symtab.default (a, []) | _ => I));
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(* constraints *)
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fun redeclare_skolems ctxt = ctxt |> map_constraints (apfst (fn types =>
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  let
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    fun decl (x, x') =
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      (case default_type ctxt x' of
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        SOME T => Vartab.update ((x, ~1), T)
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      | NONE => I);
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  in fold_rev decl (fixes_of ctxt) types end));
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fun declare_constraints t = map_constraints (fn (types, sorts) =>
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  let
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    val 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) t types;
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    val sorts' = fold_types (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)) t sorts;
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  in (types', sorts') end)
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  #> declare_type_names t
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  #> redeclare_skolems;
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(* common declarations *)
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fun declare_internal t =
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  declare_names t #>
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  declare_type_occs t;
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fun declare_term t =
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  declare_internal t #>
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  declare_constraints t;
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fun declare_thm th = fold declare_internal (Thm.full_prop_of th :: Thm.hyps_of th);
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fun thm_context th = declare_thm th (Context.init_proof (Thm.theory_of_thm th));
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(* renaming term/type frees *)
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fun variant_frees ctxt ts frees =
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  let
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    val names = names_of (fold declare_names ts ctxt);
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    val xs = fst (Name.variants (map #1 frees) names);
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  in xs ~~ map snd frees end;
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(** fixes **)
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local
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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 new_fixes names' xs xs' =
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  map_names (K names') #>
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  map_fixes (fn fixes => (rev (xs ~~ xs') @ fixes)) #>
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  fold (declare_constraints o Syntax.free) xs' #>
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  pair xs';
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in
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fun add_fixes xs ctxt =
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  let
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    val _ =
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      (case filter (can Name.dest_skolem) xs of [] => ()
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      | bads => error ("Illegal internal Skolem constant(s): " ^ commas_quote bads));
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    val _ = no_dups (duplicates (op =) xs);
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    val (ys, zs) = split_list (fixes_of ctxt);
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    val names = names_of ctxt;
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    val (xs', names') =
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      if is_body ctxt then Name.variants xs names |>> map Name.skolem
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      else (no_dups (xs inter_string ys); no_dups (xs inter_string zs);
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        (xs, fold Name.declare xs names));
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  in ctxt |> new_fixes names' xs xs' end;
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fun invent_fixes raw_xs ctxt =
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  let
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    val names = names_of ctxt;
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    val xs = map Name.clean raw_xs;
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    val (xs', names') = Name.variants xs names |>> map Name.skolem;
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  in ctxt |> new_fixes names' xs xs' end;
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end;
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fun add_fixes_direct xs ctxt = ctxt
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  |> set_body false
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  |> (snd o add_fixes xs)
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  |> restore_body ctxt;
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fun fix_frees t ctxt = ctxt
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  |> add_fixes_direct
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      (rev (fold_aterms (fn Free (x, _) =>
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        if is_fixed ctxt x then I else insert (op =) x | _ => I) t []))
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  |> declare_term t;
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fun invent_types Ss ctxt =
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  let
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    val tfrees = Name.invents (names_of ctxt) "'a" (length Ss) ~~ Ss;
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    val ctxt' = fold (declare_constraints o Logic.mk_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 declared_outer = is_declared 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 declared_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_type_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_type_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 inner' = fold (declare_type_occs o Thm.full_prop_of) ths inner;
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  in map (Thm.generalize (inst inner' outer) (fold Thm.maxidx_thm ths ~1 + 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 ren = if is_open then I else Name.internal;
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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 (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 ((map #2 instT', 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 (((map #2 instT', map #2 inst'), ths'), ctxt') end;
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(* import/export *)
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fun gen_trade imp exp ctxt f ths =
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  let val ((_, ths'), ctxt') = imp ths ctxt
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  in exp ctxt' ctxt (f ths') end;
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val tradeT = gen_trade importT exportT;
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val trade = gen_trade (import true) export;
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(* focus on outermost parameters *)
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fun forall_elim_prop t prop =
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  Thm.beta_conversion false (Thm.capply (#2 (Thm.dest_comb prop)) t)
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  |> Thm.cprop_of |> Thm.dest_comb |> #2;
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fun focus goal ctxt =
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  let
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    val cert = Thm.cterm_of (Thm.theory_of_cterm goal);
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    val t = Thm.term_of goal;
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    val ps = Term.variant_frees t (Term.strip_all_vars t);   (*as they are printed :-*)
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    val (xs, Ts) = split_list ps;
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    val (xs', ctxt') = invent_fixes xs ctxt;
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    val ps' = ListPair.map (cert o Free) (xs', Ts);
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    val goal' = fold forall_elim_prop ps' goal;
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  in ((ps', goal'), ctxt') end;
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   377
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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 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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   390
    val occs1 = type_occs_of ctxt1;
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    val occs2 = type_occs_of ctxt2;
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    val extras = Symtab.fold (fn (a, xs) =>
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   393
      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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   395
    val frees = map #2 extras |> sort_distinct string_ord;
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  in
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   397
    if null extras then ()
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   398
    else warning ("Introduced fixed type variable(s): " ^ commas tfrees ^ " in " ^
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   399
      space_implode " or " (map quote frees))
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   400
  end;
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   401
wenzelm@19899
   402
wenzelm@20149
   403
(* polymorphic terms *)
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   404
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   405
fun polymorphic ctxt ts =
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  let
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   407
    val ctxt' = fold declare_term ts ctxt;
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   408
    val occs = type_occs_of ctxt;
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   409
    val occs' = type_occs_of ctxt';
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   410
    val types = Symtab.fold (fn (a, _) => if Symtab.defined occs a then I else cons a) occs' [];
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   411
    val idx = fold (Term.fold_types Term.maxidx_typ) ts ~1 + 1;
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   412
  in map (Term.generalize (types, []) idx) ts end;
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   413
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   414
fun hidden_polymorphism t T =
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   415
  let
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   416
    val tvarsT = Term.add_tvarsT T [];
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   417
    val extra_tvars = Term.fold_types (Term.fold_atyps
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   418
      (fn TVar v => if member (op =) tvarsT v then I else insert (op =) v | _ => I)) t [];
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   419
  in extra_tvars end;
wenzelm@19899
   420
wenzelm@20162
   421
wenzelm@20162
   422
wenzelm@20162
   423
(** term bindings **)
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   424
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   425
fun add_bind (xi, NONE) = map_binds (Vartab.delete_safe xi)
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   426
  | add_bind ((x, i), SOME t) =
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   427
      let
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   428
        val T = Term.fastype_of t;
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   429
        val t' =
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   430
          if null (hidden_polymorphism t T) then t
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   431
          else Var ((x ^ "_has_extra_type_vars_on_rhs", i), T);
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   432
      in declare_term t' #> map_binds (Vartab.update ((x, i), (T, t'))) end;
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   433
wenzelm@19899
   434
val add_binds = fold add_bind;
wenzelm@19899
   435
wenzelm@19899
   436
fun expand_binds ctxt =
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   437
  let
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   438
    val binds = binds_of ctxt;
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   439
    fun expand (t as Var (xi, T)) =
wenzelm@19899
   440
          (case Vartab.lookup binds xi of
wenzelm@19899
   441
            SOME u => Envir.expand_atom T u
wenzelm@19899
   442
          | NONE => t)
wenzelm@19899
   443
      | expand t = t;
wenzelm@19899
   444
  in Envir.beta_norm o Term.map_aterms expand end;
wenzelm@19899
   445
wenzelm@19899
   446
end;