src/HOL/typedef.ML
author clasohm
Wed Mar 13 11:55:25 1996 +0100 (1996-03-13 ago)
changeset 1574 5a63ab90ee8a
parent 1475 7f5a4cd08209
child 2238 c72a23bbe762
permissions -rw-r--r--
modified primrec so it can be used in MiniML/Type.thy
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(*  Title:      HOL/typedef.ML
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    ID:         $Id$
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    Author:     Markus Wenzel, TU Muenchen
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Internal interface for typedef definitions.
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*)
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signature TYPEDEF =
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sig
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  val prove_nonempty: cterm -> thm list -> tactic option -> thm
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  val add_typedef: string -> string * string list * mixfix ->
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    string -> string list -> thm list -> tactic option -> theory -> theory
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  val add_typedef_i: string -> string * string list * mixfix ->
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    term -> string list -> thm list -> tactic option -> theory -> theory
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end;
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structure Typedef: TYPEDEF =
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struct
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open Syntax Logic HOLogic;
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(* prove non-emptyness of a set *)   (*exception ERROR*)
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val is_def = is_equals o #prop o rep_thm;
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fun prove_nonempty cset thms usr_tac =
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  let
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    val {T = setT, t = set, maxidx, sign} = rep_cterm cset;
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    val T = dest_setT setT;
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    val goal =
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      cterm_of sign (mk_Trueprop (mk_mem (Var (("x", maxidx + 1), T), set)));
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    val tac =
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      TRY (rewrite_goals_tac (filter is_def thms)) THEN
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      TRY (REPEAT_FIRST (resolve_tac (filter_out is_def thms))) THEN
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      if_none usr_tac (TRY (ALLGOALS (fast_tac set_cs)));
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  in
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    prove_goalw_cterm [] goal (K [tac])
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  end
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  handle ERROR =>
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    error ("Failed to prove non-emptyness of " ^ quote (string_of_cterm cset));
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(* ext_typedef *)
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fun ext_typedef prep_term name (t, vs, mx) raw_set axms thms usr_tac thy =
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  let
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    val dummy = require_thy thy "Set" "typedef definitions";
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    val sign = sign_of thy;
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    (*rhs*)
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    val cset = prep_term sign raw_set;
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    val {T = setT, t = set, ...} = rep_cterm cset;
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    val rhs_tfrees = term_tfrees set;
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    val oldT = dest_setT setT handle TYPE _ =>
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      error ("Not a set type: " ^ quote (Sign.string_of_typ sign setT));
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    (*lhs*)
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    val lhs_tfrees =
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      map (fn v => (v, if_none (assoc (rhs_tfrees, v)) termS)) vs;
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    val tname = type_name t mx;
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    val tlen = length vs;
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    val newT = Type (tname, map TFree lhs_tfrees);
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    val Rep_name = "Rep_" ^ name;
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    val Abs_name = "Abs_" ^ name;
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    val setC = Const (name, setT);
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    val RepC = Const (Rep_name, newT --> oldT);
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    val AbsC = Const (Abs_name, oldT --> newT);
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    val x_new = Free ("x", newT);
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    val y_old = Free ("y", oldT);
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    (*axioms*)
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    val rep_type = mk_Trueprop (mk_mem (RepC $ x_new, setC));
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    val rep_type_inv = mk_Trueprop (mk_eq (AbsC $ (RepC $ x_new), x_new));
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    val abs_type_inv = mk_implies (mk_Trueprop (mk_mem (y_old, setC)),
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      mk_Trueprop (mk_eq (RepC $ (AbsC $ y_old), y_old)));
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    (* errors *)
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    val show_names = commas_quote o map fst;
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    val illegal_vars =
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      if null (term_vars set) andalso null (term_tvars set) then []
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      else ["Illegal schematic variable(s) on rhs"];
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    val dup_lhs_tfrees =
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      (case duplicates lhs_tfrees of [] => []
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      | dups => ["Duplicate type variables on lhs: " ^ show_names dups]);
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    val extra_rhs_tfrees =
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      (case gen_rems (op =) (rhs_tfrees, lhs_tfrees) of [] => []
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      | extras => ["Extra type variables on rhs: " ^ show_names extras]);
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    val illegal_frees =
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      (case term_frees set of [] => []
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      | xs => ["Illegal variables on rhs: " ^ show_names (map dest_Free xs)]);
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    val errs = illegal_vars @ dup_lhs_tfrees @ extra_rhs_tfrees @ illegal_frees;
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  in
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    if null errs then ()
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    else error (cat_lines errs);
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    prove_nonempty cset (map (get_axiom thy) axms @ thms) usr_tac;
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    thy
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    |> add_types [(t, tlen, mx)]
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    |> add_arities
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     [(tname, replicate tlen logicS, logicS),
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      (tname, replicate tlen termS, termS)]
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    |> add_consts_i
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     [(name, setT, NoSyn),
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      (Rep_name, newT --> oldT, NoSyn),
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      (Abs_name, oldT --> newT, NoSyn)]
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    |> add_defs_i
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     [(name ^ "_def", mk_equals (setC, set))]
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    |> add_axioms_i
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     [(Rep_name, rep_type),
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      (Rep_name ^ "_inverse", rep_type_inv),
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      (Abs_name ^ "_inverse", abs_type_inv)]
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  end
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  handle ERROR =>
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    error ("The error(s) above occurred in typedef definition " ^ quote name);
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(* external interfaces *)
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fun cert_term sg tm =
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  cterm_of sg tm handle TERM (msg, _) => error msg;
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fun read_term sg str =
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  read_cterm sg (str, termTVar);
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val add_typedef = ext_typedef read_term;
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val add_typedef_i = ext_typedef cert_term;
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end;
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