haftmann@24219: (*  Title:      Pure/Isar/code_unit.ML
haftmann@24219:     Author:     Florian Haftmann, TU Muenchen
haftmann@24219: 
haftmann@24844: Basic notions of code generation.  Auxiliary.
haftmann@24219: *)
haftmann@24219: 
haftmann@24219: signature CODE_UNIT =
haftmann@24219: sig
haftmann@24844:   (*generic non-sense*)
haftmann@24844:   val bad_thm: string -> 'a
haftmann@28368:   val error_thm: ('a -> 'b) -> 'a -> 'b
haftmann@28368:   val warning_thm: ('a -> 'b) -> 'a -> 'b option
haftmann@28368:   val try_thm: ('a -> 'b) -> 'a -> 'b option
haftmann@24844: 
haftmann@24844:   (*typ instantiations*)
haftmann@26970:   val typscheme: theory -> string * typ -> (string * sort) list * typ
haftmann@28423:   val inst_thm: theory -> sort Vartab.table -> thm -> thm
haftmann@28423:   val constrain_thm: theory -> sort -> thm -> thm
haftmann@24844: 
haftmann@26747:   (*constant aliasses*)
haftmann@26354:   val add_const_alias: thm -> theory -> theory
haftmann@28346:   val triv_classes: theory -> class list
haftmann@26747:   val resubst_alias: theory -> string -> string
haftmann@26747: 
haftmann@26747:   (*constants*)
haftmann@24219:   val string_of_typ: theory -> typ -> string
haftmann@24423:   val string_of_const: theory -> string -> string
haftmann@24423:   val no_args: theory -> string -> int
haftmann@26112:   val check_const: theory -> term -> string
haftmann@24219:   val read_bare_const: theory -> string -> string * typ
haftmann@24423:   val read_const: theory -> string -> string
haftmann@24219: 
haftmann@24844:   (*constructor sets*)
haftmann@24423:   val constrset_of_consts: theory -> (string * typ) list
haftmann@24219:     -> string * ((string * sort) list * (string * typ list) list)
haftmann@24219: 
haftmann@30022:   (*code equations*)
haftmann@28423:   val assert_eqn: theory -> thm -> thm
haftmann@28423:   val mk_eqn: theory -> thm -> thm * bool
haftmann@28708:   val assert_linear: (string -> bool) -> thm * bool -> thm * bool
haftmann@28423:   val const_eqn: thm -> string
haftmann@28423:   val const_typ_eqn: thm -> string * typ
haftmann@28423:   val head_eqn: theory -> thm -> string * ((string * sort) list * typ)
haftmann@28423:   val expand_eta: theory -> int -> thm -> thm
haftmann@28368:   val rewrite_eqn: simpset -> thm -> thm
haftmann@27582:   val rewrite_head: thm list -> thm -> thm
haftmann@28423:   val norm_args: theory -> thm list -> thm list 
haftmann@28423:   val norm_varnames: theory -> (string -> string) -> (string -> string) -> thm list -> thm list
haftmann@24844: 
haftmann@24844:   (*case certificates*)
haftmann@24844:   val case_cert: thm -> string * (int * string list)
haftmann@24219: end;
haftmann@24219: 
haftmann@28054: structure Code_Unit: CODE_UNIT =
haftmann@24219: struct
haftmann@24219: 
haftmann@24219: 
haftmann@24219: (* auxiliary *)
haftmann@24219: 
haftmann@24219: exception BAD_THM of string;
haftmann@24219: fun bad_thm msg = raise BAD_THM msg;
haftmann@24219: fun error_thm f thm = f thm handle BAD_THM msg => error msg;
haftmann@24219: fun warning_thm f thm = SOME (f thm) handle BAD_THM msg
haftmann@24219:   => (warning ("code generator: " ^ msg); NONE);
haftmann@24624: fun try_thm f thm = SOME (f thm) handle BAD_THM _ => NONE;
haftmann@24219: 
wenzelm@26939: fun string_of_typ thy = setmp show_sorts true (Syntax.string_of_typ_global thy);
haftmann@25597: fun string_of_const thy c = case AxClass.inst_of_param thy c
haftmann@24423:  of SOME (c, tyco) => Sign.extern_const thy c ^ " " ^ enclose "[" "]" (Sign.extern_type thy tyco)
haftmann@24423:   | NONE => Sign.extern_const thy c;
haftmann@24219: 
haftmann@24423: fun no_args thy = length o fst o strip_type o Sign.the_const_type thy;
haftmann@24219: 
haftmann@26354: 
haftmann@26354: (* utilities *)
haftmann@26354: 
haftmann@26970: fun typscheme thy (c, ty) =
haftmann@26970:   let
haftmann@30022:     val ty' = Logic.unvarifyT ty;
haftmann@30022:     fun dest (TFree (v, sort)) = (v, sort)
haftmann@26970:       | dest ty = error ("Illegal type parameter in type scheme: " ^ Syntax.string_of_typ_global thy ty);
haftmann@30022:     val vs = map dest (Sign.const_typargs thy (c, ty'));
haftmann@30022:   in (vs, Type.strip_sorts ty') end;
haftmann@26970: 
haftmann@28423: fun inst_thm thy tvars' thm =
haftmann@26354:   let
haftmann@26354:     val tvars = (Term.add_tvars o Thm.prop_of) thm [];
haftmann@28310:     val inter_sort = Sorts.inter_sort (Sign.classes_of thy);
haftmann@28310:     fun mk_inst (tvar as (v, sort)) = case Vartab.lookup tvars' v
haftmann@28310:      of SOME sort' => SOME (pairself (Thm.ctyp_of thy o TVar)
haftmann@28310:           (tvar, (v, inter_sort (sort, sort'))))
haftmann@26354:       | NONE => NONE;
haftmann@26354:     val insts = map_filter mk_inst tvars;
haftmann@26354:   in Thm.instantiate (insts, []) thm end;
haftmann@26354: 
haftmann@28423: fun constrain_thm thy sort thm =
haftmann@26354:   let
haftmann@26354:     val constrain = curry (Sorts.inter_sort (Sign.classes_of thy)) sort
haftmann@26354:     val tvars = (Term.add_tvars o Thm.prop_of) thm [];
haftmann@26354:     fun mk_inst (tvar as (v, sort)) = pairself (Thm.ctyp_of thy o TVar o pair v)
haftmann@26354:       (sort, constrain sort)
haftmann@26354:     val insts = map mk_inst tvars;
haftmann@26354:   in Thm.instantiate (insts, []) thm end;
haftmann@26354: 
haftmann@28423: fun expand_eta thy k thm =
haftmann@26354:   let
haftmann@26354:     val (lhs, rhs) = (Logic.dest_equals o Thm.plain_prop_of) thm;
haftmann@26354:     val (head, args) = strip_comb lhs;
haftmann@26354:     val l = if k = ~1
haftmann@26354:       then (length o fst o strip_abs) rhs
haftmann@26354:       else Int.max (0, k - length args);
haftmann@26354:     val used = Name.make_context (map (fst o fst) (Term.add_vars lhs []));
haftmann@26354:     fun get_name _ 0 = pair []
haftmann@26354:       | get_name (Abs (v, ty, t)) k =
haftmann@26354:           Name.variants [v]
haftmann@26354:           ##>> get_name t (k - 1)
haftmann@26354:           #>> (fn ([v'], vs') => (v', ty) :: vs')
haftmann@26354:       | get_name t k = 
haftmann@26354:           let
haftmann@26354:             val (tys, _) = (strip_type o fastype_of) t
haftmann@26354:           in case tys
haftmann@26354:            of [] => raise TERM ("expand_eta", [t])
haftmann@26354:             | ty :: _ =>
haftmann@26354:                 Name.variants [""]
haftmann@26354:                 #-> (fn [v] => get_name (t $ Var ((v, 0), ty)) (k - 1)
haftmann@26354:                 #>> (fn vs' => (v, ty) :: vs'))
haftmann@26354:           end;
haftmann@26354:     val (vs, _) = get_name rhs l used;
haftmann@26354:     fun expand (v, ty) thm = Drule.fun_cong_rule thm
haftmann@26354:       (Thm.cterm_of thy (Var ((v, 0), ty)));
haftmann@26354:   in
haftmann@26354:     thm
haftmann@26354:     |> fold expand vs
haftmann@26354:     |> Conv.fconv_rule Drule.beta_eta_conversion
haftmann@26354:   end;
haftmann@26354: 
haftmann@28368: fun eqn_conv conv =
haftmann@26354:   let
haftmann@26354:     fun lhs_conv ct = if can Thm.dest_comb ct
haftmann@26354:       then (Conv.combination_conv lhs_conv conv) ct
haftmann@26354:       else Conv.all_conv ct;
haftmann@26354:   in Conv.combination_conv (Conv.arg_conv lhs_conv) conv end;
haftmann@26354: 
haftmann@26354: fun head_conv conv =
haftmann@26354:   let
haftmann@26354:     fun lhs_conv ct = if can Thm.dest_comb ct
haftmann@26354:       then (Conv.fun_conv lhs_conv) ct
haftmann@26354:       else conv ct;
haftmann@26354:   in Conv.fun_conv (Conv.arg_conv lhs_conv) end;
haftmann@26354: 
haftmann@28368: val rewrite_eqn = Conv.fconv_rule o eqn_conv o Simplifier.rewrite;
haftmann@26354: val rewrite_head = Conv.fconv_rule o head_conv o MetaSimplifier.rewrite false;
haftmann@26354: 
haftmann@28423: fun norm_args thy thms =
haftmann@26354:   let
haftmann@26354:     val num_args_of = length o snd o strip_comb o fst o Logic.dest_equals;
haftmann@28310:     val k = fold (curry Int.max o num_args_of o Thm.prop_of) thms 0;
haftmann@26354:   in
haftmann@26354:     thms
haftmann@28423:     |> map (expand_eta thy k)
haftmann@26354:     |> map (Conv.fconv_rule Drule.beta_eta_conversion)
haftmann@26354:   end;
haftmann@26354: 
haftmann@28423: fun canonical_tvars thy purify_tvar thm =
haftmann@26354:   let
haftmann@28423:     val ctyp = Thm.ctyp_of thy;
haftmann@26354:     fun tvars_subst_for thm = (fold_types o fold_atyps)
haftmann@26354:       (fn TVar (v_i as (v, _), sort) => let
haftmann@26354:             val v' = purify_tvar v
haftmann@26354:           in if v = v' then I
haftmann@26354:           else insert (op =) (v_i, (v', sort)) end
haftmann@26354:         | _ => I) (prop_of thm) [];
haftmann@26354:     fun mk_inst (v_i, (v', sort)) (maxidx, acc) =
haftmann@26354:       let
haftmann@26354:         val ty = TVar (v_i, sort)
haftmann@26354:       in
haftmann@26354:         (maxidx + 1, (ctyp ty, ctyp (TVar ((v', maxidx), sort))) :: acc)
haftmann@26354:       end;
haftmann@26354:     val maxidx = Thm.maxidx_of thm + 1;
haftmann@26354:     val (_, inst) = fold mk_inst (tvars_subst_for thm) (maxidx + 1, []);
haftmann@26354:   in Thm.instantiate (inst, []) thm end;
haftmann@26354: 
haftmann@28423: fun canonical_vars thy purify_var thm =
haftmann@26354:   let
haftmann@28423:     val cterm = Thm.cterm_of thy;
haftmann@26354:     fun vars_subst_for thm = fold_aterms
haftmann@26354:       (fn Var (v_i as (v, _), ty) => let
haftmann@26354:             val v' = purify_var v
haftmann@26354:           in if v = v' then I
haftmann@26354:           else insert (op =) (v_i, (v', ty)) end
haftmann@26354:         | _ => I) (prop_of thm) [];
haftmann@26354:     fun mk_inst (v_i as (v, i), (v', ty)) (maxidx, acc) =
haftmann@26354:       let
haftmann@26354:         val t = Var (v_i, ty)
haftmann@26354:       in
haftmann@26354:         (maxidx + 1, (cterm t, cterm (Var ((v', maxidx), ty))) :: acc)
haftmann@26354:       end;
haftmann@26354:     val maxidx = Thm.maxidx_of thm + 1;
haftmann@26354:     val (_, inst) = fold mk_inst (vars_subst_for thm) (maxidx + 1, []);
haftmann@26354:   in Thm.instantiate ([], inst) thm end;
haftmann@26354: 
haftmann@26354: fun canonical_absvars purify_var thm =
haftmann@26354:   let
haftmann@26354:     val t = Thm.plain_prop_of thm;
haftmann@26354:     val t' = Term.map_abs_vars purify_var t;
haftmann@26354:   in Thm.rename_boundvars t t' thm end;
haftmann@26354: 
haftmann@28423: fun norm_varnames thy purify_tvar purify_var thms =
haftmann@26354:   let
haftmann@26354:     fun burrow_thms f [] = []
haftmann@26354:       | burrow_thms f thms =
haftmann@26354:           thms
haftmann@26354:           |> Conjunction.intr_balanced
haftmann@26354:           |> f
haftmann@26354:           |> Conjunction.elim_balanced (length thms)
haftmann@26354:   in
haftmann@26354:     thms
haftmann@28423:     |> burrow_thms (canonical_tvars thy purify_tvar)
haftmann@28423:     |> map (canonical_vars thy purify_var)
haftmann@26354:     |> map (canonical_absvars purify_var)
haftmann@26354:     |> map Drule.zero_var_indexes
haftmann@26354:   end;
haftmann@26354: 
haftmann@28346: 
haftmann@26354: (* const aliasses *)
haftmann@26354: 
haftmann@26354: structure ConstAlias = TheoryDataFun
haftmann@26354: (
haftmann@26747:   type T = ((string * string) * thm) list * class list;
haftmann@26747:   val empty = ([], []);
haftmann@26354:   val copy = I;
wenzelm@26618:   val extend = I;
wenzelm@29288:   fun merge _ ((alias1, classes1), (alias2, classes2)) : T =
haftmann@26747:     (Library.merge (eq_snd Thm.eq_thm_prop) (alias1, alias2),
haftmann@26747:       Library.merge (op =) (classes1, classes2));
haftmann@26354: );
haftmann@26354: 
haftmann@28423: fun add_const_alias thm thy =
haftmann@26354:   let
haftmann@28423:     val lhs_rhs = case try Logic.dest_equals (Thm.prop_of thm)
haftmann@26354:      of SOME lhs_rhs => lhs_rhs
haftmann@26354:       | _ => error ("Not an equation: " ^ Display.string_of_thm thm);
haftmann@26354:     val c_c' = case try (pairself (AxClass.unoverload_const thy o dest_Const)) lhs_rhs
haftmann@26354:      of SOME c_c' => c_c'
haftmann@26354:       | _ => error ("Not an equation with two constants: " ^ Display.string_of_thm thm);
haftmann@26747:     val some_class = the_list (AxClass.class_of_param thy (snd c_c'));
haftmann@28423:   in thy |>
haftmann@26747:     ConstAlias.map (fn (alias, classes) =>
haftmann@26747:       ((c_c', thm) :: alias, fold (insert (op =)) some_class classes))
haftmann@26747:   end;
haftmann@26354: 
haftmann@26747: fun resubst_alias thy =
haftmann@26747:   let
haftmann@26747:     val alias = fst (ConstAlias.get thy);
haftmann@26747:     val subst_inst_param = Option.map fst o AxClass.inst_of_param thy;
haftmann@26747:     fun subst_alias c =
haftmann@26747:       get_first (fn ((c', c''), _) => if c = c'' then SOME c' else NONE) alias;
haftmann@26747:   in
haftmann@26747:     perhaps subst_inst_param
haftmann@26747:     #> perhaps subst_alias
haftmann@26747:   end;
haftmann@26747: 
haftmann@26747: val triv_classes = snd o ConstAlias.get;
haftmann@26747: 
haftmann@28346: 
wenzelm@26610: (* reading constants as terms *)
haftmann@24219: 
haftmann@26112: fun check_bare_const thy t = case try dest_Const t
haftmann@26112:  of SOME c_ty => c_ty
wenzelm@26939:   | NONE => error ("Not a constant: " ^ Syntax.string_of_term_global thy t);
haftmann@26112: 
haftmann@28346: fun check_const thy = AxClass.unoverload_const thy o check_bare_const thy;
haftmann@26112: 
haftmann@26112: fun read_bare_const thy = check_bare_const thy o Syntax.read_term_global thy;
haftmann@24219: 
haftmann@28346: fun read_const thy = AxClass.unoverload_const thy o read_bare_const thy;
haftmann@24219: 
haftmann@24219: 
haftmann@24423: (* constructor sets *)
haftmann@24219: 
haftmann@24423: fun constrset_of_consts thy cs =
haftmann@24219:   let
haftmann@28704:     val _ = map (fn (c, _) => if (is_some o AxClass.class_of_param thy) c
haftmann@28704:       then error ("Is a class parameter: " ^ string_of_const thy c) else ()) cs;
haftmann@24423:     fun no_constr (c, ty) = error ("Not a datatype constructor: " ^ string_of_const thy c
haftmann@24423:       ^ " :: " ^ string_of_typ thy ty);
haftmann@24423:     fun last_typ c_ty ty =
haftmann@24423:       let
wenzelm@29270:         val frees = OldTerm.typ_tfrees ty;
haftmann@24423:         val (tyco, vs) = ((apsnd o map) (dest_TFree) o dest_Type o snd o strip_type) ty
haftmann@24423:           handle TYPE _ => no_constr c_ty
haftmann@24423:         val _ = if has_duplicates (eq_fst (op =)) vs then no_constr c_ty else ();
haftmann@24423:         val _ = if length frees <> length vs then no_constr c_ty else ();
haftmann@24423:       in (tyco, vs) end;
haftmann@24423:     fun ty_sorts (c, ty) =
haftmann@24423:       let
haftmann@24423:         val ty_decl = (Logic.unvarifyT o Sign.the_const_type thy) c;
haftmann@26970:         val (tyco, _) = last_typ (c, ty) ty_decl;
haftmann@24423:         val (_, vs) = last_typ (c, ty) ty;
haftmann@28015:       in ((tyco, map snd vs), (c, (map fst vs, ty))) end;
haftmann@24423:     fun add ((tyco', sorts'), c) ((tyco, sorts), cs) =
haftmann@24423:       let
haftmann@24423:         val _ = if tyco' <> tyco
haftmann@24423:           then error "Different type constructors in constructor set"
haftmann@24423:           else ();
haftmann@24423:         val sorts'' = map2 (curry (Sorts.inter_sort (Sign.classes_of thy))) sorts' sorts
haftmann@24423:       in ((tyco, sorts), c :: cs) end;
haftmann@24423:     fun inst vs' (c, (vs, ty)) =
haftmann@24423:       let
haftmann@24423:         val the_v = the o AList.lookup (op =) (vs ~~ vs');
haftmann@24423:         val ty' = map_atyps (fn TFree (v, _) => TFree (the_v v)) ty;
haftmann@24423:       in (c, (fst o strip_type) ty') end;
haftmann@24423:     val c' :: cs' = map ty_sorts cs;
haftmann@24423:     val ((tyco, sorts), cs'') = fold add cs' (apsnd single c');
wenzelm@24848:     val vs = Name.names Name.context Name.aT sorts;
haftmann@24423:     val cs''' = map (inst vs) cs'';
haftmann@30022:   in (tyco, (vs, rev cs''')) end;
haftmann@24219: 
haftmann@24219: 
haftmann@30022: (* code equations *)
haftmann@24219: 
haftmann@28423: fun assert_eqn thy thm =
haftmann@24219:   let
haftmann@24219:     val (lhs, rhs) = (Logic.dest_equals o Thm.plain_prop_of) thm
haftmann@24219:       handle TERM _ => bad_thm ("Not an equation: " ^ Display.string_of_thm thm)
haftmann@24219:           | THM _ => bad_thm ("Not an equation: " ^ Display.string_of_thm thm);
haftmann@24219:     fun vars_of t = fold_aterms
haftmann@24219:      (fn Var (v, _) => insert (op =) v
haftmann@24219:        | Free _ => bad_thm ("Illegal free variable in rewrite theorem\n"
haftmann@24219:            ^ Display.string_of_thm thm)
haftmann@24219:        | _ => I) t [];
haftmann@24219:     fun tvars_of t = fold_term_types
haftmann@24219:      (fn _ => fold_atyps (fn TVar (v, _) => insert (op =) v
haftmann@24219:                           | TFree _ => bad_thm 
haftmann@24219:       ("Illegal free type variable in rewrite theorem\n" ^ Display.string_of_thm thm))) t [];
haftmann@24219:     val lhs_vs = vars_of lhs;
haftmann@24219:     val rhs_vs = vars_of rhs;
haftmann@24219:     val lhs_tvs = tvars_of lhs;
haftmann@24219:     val rhs_tvs = tvars_of lhs;
haftmann@24219:     val _ = if null (subtract (op =) lhs_vs rhs_vs)
haftmann@24219:       then ()
haftmann@24219:       else bad_thm ("Free variables on right hand side of rewrite theorem\n"
haftmann@24219:         ^ Display.string_of_thm thm);
haftmann@24219:     val _ = if null (subtract (op =) lhs_tvs rhs_tvs)
haftmann@24219:       then ()
haftmann@24219:       else bad_thm ("Free type variables on right hand side of rewrite theorem\n"
haftmann@28423:         ^ Display.string_of_thm thm)    val (head, args) = (strip_comb o fst o Logic.dest_equals o Thm.plain_prop_of) thm;
haftmann@28423:     val (c, ty) = case head of Const c_ty => c_ty | _ =>
haftmann@24219:       bad_thm ("Equation not headed by constant\n" ^ Display.string_of_thm thm);
haftmann@24219:     fun check _ (Abs _) = bad_thm
haftmann@24219:           ("Abstraction on left hand side of equation\n"
haftmann@24219:             ^ Display.string_of_thm thm)
haftmann@24219:       | check 0 (Var _) = ()
haftmann@24219:       | check _ (Var _) = bad_thm
haftmann@30022:           ("Variable with application on left hand side of code equation\n"
haftmann@24219:             ^ Display.string_of_thm thm)
haftmann@24219:       | check n (t1 $ t2) = (check (n+1) t1; check 0 t2)
haftmann@24219:       | check n (Const (_, ty)) = if n <> (length o fst o strip_type) ty
haftmann@24219:           then bad_thm
haftmann@24219:             ("Partially applied constant on left hand side of equation\n"
haftmann@24219:                ^ Display.string_of_thm thm)
haftmann@24219:           else ();
haftmann@24219:     val _ = map (check 0) args;
haftmann@28423:     val ty_decl = Sign.the_const_type thy c;
haftmann@28423:     val _ = if Sign.typ_equiv thy (Type.strip_sorts ty_decl, Type.strip_sorts ty)
haftmann@28423:       then () else bad_thm ("Type\n" ^ string_of_typ thy ty
haftmann@30022:            ^ "\nof code equation\n"
haftmann@28423:            ^ Display.string_of_thm thm
haftmann@28423:            ^ "\nis incompatible with declared function type\n"
haftmann@28423:            ^ string_of_typ thy ty_decl)
haftmann@28423:   in thm end;
haftmann@24219: 
haftmann@28423: fun add_linear thm =
haftmann@24219:   let
haftmann@28423:     val (_, args) = (strip_comb o fst o Logic.dest_equals o Thm.plain_prop_of) thm;
haftmann@28423:     val linear = not (has_duplicates (op =)
haftmann@28423:       ((fold o fold_aterms) (fn Var (v, _) => cons v | _ => I) args []))
haftmann@28423:   in (thm, linear) end;
haftmann@28423: 
haftmann@28708: fun assert_pat is_cons thm =
haftmann@28708:   let
haftmann@28708:     val args = (snd o strip_comb o fst o Logic.dest_equals o Thm.plain_prop_of) thm;
haftmann@28708:     val _ = (map o map_aterms) (fn t as Const (c, _) => if is_cons c then t
haftmann@28708:           else bad_thm ("Not a constructor on left hand side of equation: "
haftmann@28708:             ^ quote c ^ ",\n in equation\n" ^ Display.string_of_thm thm)
haftmann@28708:       | t => t) args;
haftmann@28708:   in thm end;
haftmann@28708: 
haftmann@28708: fun assert_linear is_cons (thm, false) = (thm, false)
haftmann@28708:   | assert_linear is_cons (thm, true) = if snd (add_linear (assert_pat is_cons thm)) then (thm, true)
haftmann@28423:       else bad_thm
haftmann@30022:         ("Duplicate variables on left hand side of code equation:\n"
haftmann@28423:           ^ Display.string_of_thm thm);
haftmann@28423: 
haftmann@28423: 
haftmann@28423: fun mk_eqn thy = add_linear o assert_eqn thy o AxClass.unoverload thy
haftmann@28423:   o LocalDefs.meta_rewrite_rule (ProofContext.init thy);
haftmann@28423: 
haftmann@28423: val const_typ_eqn = dest_Const o fst o strip_comb o fst o Logic.dest_equals o Thm.plain_prop_of;
haftmann@28423: val const_eqn = fst o const_typ_eqn;
haftmann@28423: fun head_eqn thy thm = let val (c, ty) = const_typ_eqn thm in (c, typscheme thy (c, ty)) end;
haftmann@24219: 
haftmann@24219: 
haftmann@24844: (* case cerificates *)
haftmann@24844: 
haftmann@24917: fun case_certificate thm =
haftmann@24844:   let
haftmann@24917:     val ((head, raw_case_expr), cases) = (apfst Logic.dest_equals
haftmann@24917:       o apsnd Logic.dest_conjunctions o Logic.dest_implies o Thm.prop_of) thm;
haftmann@24844:     val _ = case head of Free _ => true
haftmann@24844:       | Var _ => true
haftmann@24844:       | _ => raise TERM ("case_cert", []);
haftmann@24917:     val ([(case_var, _)], case_expr) = Term.strip_abs_eta 1 raw_case_expr;
haftmann@24917:     val (Const (case_const, _), raw_params) = strip_comb case_expr;
haftmann@24917:     val n = find_index (fn Free (v, _) => v = case_var | _ => false) raw_params;
haftmann@24917:     val _ = if n = ~1 then raise TERM ("case_cert", []) else ();
haftmann@24917:     val params = map (fst o dest_Var) (nth_drop n raw_params);
haftmann@24917:     fun dest_case t =
haftmann@24844:       let
haftmann@24844:         val (head' $ t_co, rhs) = Logic.dest_equals t;
haftmann@24844:         val _ = if head' = head then () else raise TERM ("case_cert", []);
haftmann@24844:         val (Const (co, _), args) = strip_comb t_co;
haftmann@24844:         val (Var (param, _), args') = strip_comb rhs;
haftmann@24844:         val _ = if args' = args then () else raise TERM ("case_cert", []);
haftmann@24844:       in (param, co) end;
haftmann@24917:     fun analyze_cases cases =
haftmann@24844:       let
haftmann@24917:         val co_list = fold (AList.update (op =) o dest_case) cases [];
haftmann@24844:       in map (the o AList.lookup (op =) co_list) params end;
haftmann@24844:     fun analyze_let t =
haftmann@24844:       let
haftmann@24844:         val (head' $ arg, Var (param', _) $ arg') = Logic.dest_equals t;
haftmann@24844:         val _ = if head' = head then () else raise TERM ("case_cert", []);
haftmann@24844:         val _ = if arg' = arg then () else raise TERM ("case_cert", []);
haftmann@24844:         val _ = if [param'] = params then () else raise TERM ("case_cert", []);
haftmann@24844:       in [] end;
haftmann@24917:     fun analyze (cases as [let_case]) =
haftmann@24917:           (analyze_cases cases handle Bind => analyze_let let_case)
haftmann@24917:       | analyze cases = analyze_cases cases;
haftmann@24917:   in (case_const, (n, analyze cases)) end;
haftmann@24917: 
haftmann@24917: fun case_cert thm = case_certificate thm
haftmann@24917:   handle Bind => error "bad case certificate"
haftmann@28346:        | TERM _ => error "bad case certificate";
haftmann@24844: 
haftmann@24219: end;