make this module appeat late in Pure;
moved print_current_goals to display.ML;
added quick_and_dirty_prove_goalw_cterm (from Isar/skip_proof.ML);
added thm database functions (from Thy/thm_database.ML);
(* Title: Pure/goals.ML
ID: $Id$
Author: Lawrence C Paulson, Cambridge University Computer Laboratory
Copyright 1993 University of Cambridge
Goal stack package. The goal stack initially holds a dummy proof, and can
never become empty. Each goal stack consists of a list of levels. The
undo list is a list of goal stacks. Finally, there may be a stack of
pending proofs.
*)
signature GOALS =
sig
type proof
val reset_goals : unit -> unit
val atomic_goal : theory -> string -> thm list
val atomic_goalw : theory -> thm list -> string -> thm list
val Goal : string -> thm list
val Goalw : thm list -> string -> thm list
val ba : int -> unit
val back : unit -> unit
val bd : thm -> int -> unit
val bds : thm list -> int -> unit
val be : thm -> int -> unit
val bes : thm list -> int -> unit
val br : thm -> int -> unit
val brs : thm list -> int -> unit
val bw : thm -> unit
val bws : thm list -> unit
val by : tactic -> unit
val byev : tactic list -> unit
val chop : unit -> unit
val choplev : int -> unit
val export_thy : theory -> thm -> thm
val export : thm -> thm
val Export : thm -> thm
val fa : unit -> unit
val fd : thm -> unit
val fds : thm list -> unit
val fe : thm -> unit
val fes : thm list -> unit
val filter_goal : (term*term->bool) -> thm list -> int -> thm list
val fr : thm -> unit
val frs : thm list -> unit
val getgoal : int -> term
val gethyps : int -> thm list
val goal : theory -> string -> thm list
val goalw : theory -> thm list -> string -> thm list
val goalw_cterm : thm list -> cterm -> thm list
val pop_proof : unit -> thm list
val pr : unit -> unit
val disable_pr : unit -> unit
val enable_pr : unit -> unit
val prlev : int -> unit
val prlim : int -> unit
val premises : unit -> thm list
val prin : term -> unit
val printyp : typ -> unit
val pprint_term : term -> pprint_args -> unit
val pprint_typ : typ -> pprint_args -> unit
val print_exn : exn -> 'a
val print_sign_exn : Sign.sg -> exn -> 'a
val prove_goal : theory -> string -> (thm list -> tactic list) -> thm
val prove_goalw : theory->thm list->string->(thm list->tactic list)->thm
val prove_goalw_cterm : thm list->cterm->(thm list->tactic list)->thm
val prove_goalw_cterm_nocheck : thm list->cterm->(thm list->tactic list)->thm
val quick_and_dirty_prove_goalw_cterm: theory -> thm list -> cterm
-> (thm list -> tactic list) -> thm
val push_proof : unit -> unit
val read : string -> term
val ren : string -> int -> unit
val restore_proof : proof -> thm list
val result : unit -> thm
val result_error_fn : (thm -> string -> thm) ref
val rotate_proof : unit -> thm list
val uresult : unit -> thm
val save_proof : unit -> proof
val topthm : unit -> thm
val undo : unit -> unit
val bind_thm : string * thm -> unit
val bind_thms : string * thm list -> unit
val qed : string -> unit
val qed_goal : string -> theory -> string -> (thm list -> tactic list) -> unit
val qed_goalw : string -> theory -> thm list -> string
-> (thm list -> tactic list) -> unit
val qed_spec_mp : string -> unit
val qed_goal_spec_mp : string -> theory -> string -> (thm list -> tactic list) -> unit
val qed_goalw_spec_mp : string -> theory -> thm list -> string
-> (thm list -> tactic list) -> unit
val no_qed: unit -> unit
val thms_containing : xstring list -> (string * thm) list
val findI : int -> (string * thm) list
val findEs : int -> (string * thm) list
val findE : int -> int -> (string * thm) list
end;
structure Goals : GOALS =
struct
(*Each level of goal stack includes a proof state and alternative states,
the output of the tactic applied to the preceeding level. *)
type gstack = (thm * thm Seq.seq) list;
datatype proof = Proof of gstack list * thm list * (bool*thm->thm);
(*** References ***)
(*Current assumption list -- set by "goal".*)
val curr_prems = ref([] : thm list);
(*Return assumption list -- useful if you didn't save "goal"'s result. *)
fun premises() = !curr_prems;
(*Current result maker -- set by "goal", used by "result". *)
fun init_mkresult _ = error "No goal has been supplied in subgoal module";
val curr_mkresult = ref (init_mkresult: bool*thm->thm);
val dummy = trivial(read_cterm (Theory.sign_of ProtoPure.thy)
("PROP No_goal_has_been_supplied",propT));
(*List of previous goal stacks, for the undo operation. Set by setstate.
A list of lists!*)
val undo_list = ref([[(dummy, Seq.empty)]] : gstack list);
(* Stack of proof attempts *)
val proofstack = ref([]: proof list);
(*reset all refs*)
fun reset_goals () =
(curr_prems := []; curr_mkresult := init_mkresult;
undo_list := [[(dummy, Seq.empty)]]);
(*** Setting up goal-directed proof ***)
(*Generates the list of new theories when the proof state's signature changes*)
fun sign_error (sign,sign') =
let val names = Sign.stamp_names_of sign' \\ Sign.stamp_names_of sign
in case names of
[name] => "\nNew theory: " ^ name
| _ => "\nNew theories: " ^ space_implode ", " names
end;
(*Default action is to print an error message; could be suppressed for
special applications.*)
fun result_error_default state msg : thm =
Pretty.str "Bad final proof state:" :: Display.pretty_goals (!goals_limit) state @
[Pretty.str msg, Pretty.str "Proof failed!"] |> Pretty.chunks |> Pretty.string_of |> error;
val result_error_fn = ref result_error_default;
(* alternative to standard: this function does not discharge the hypotheses
first. Is used for locales, in the following function prepare_proof *)
fun varify th =
let val {maxidx,...} = rep_thm th
in
th |> forall_intr_frees |> forall_elim_vars (maxidx + 1)
|> Drule.strip_shyps_warning
|> zero_var_indexes |> Thm.varifyT |> Thm.compress
end;
(** exporting a theorem out of a locale means turning all meta-hyps into assumptions
and expand and cancel the locale definitions.
export goes through all levels in case of nested locales, whereas
export_thy just goes one up. **)
fun get_top_scope_thms thy =
let val sc = (Locale.get_scope_sg (Theory.sign_of thy))
in if (null sc) then (warning "No locale in theory"; [])
else map (#prop o rep_thm) (map #2 (#thms(snd(hd sc))))
end;
fun implies_intr_some_hyps thy A_set th =
let
val sign = Theory.sign_of thy;
val used_As = A_set inter #hyps(rep_thm(th));
val ctl = map (cterm_of sign) used_As
in foldl (fn (x, y) => Thm.implies_intr y x) (th, ctl)
end;
fun standard_some thy A_set th =
let val {maxidx,...} = rep_thm th
in
th |> implies_intr_some_hyps thy A_set
|> forall_intr_frees |> forall_elim_vars (maxidx + 1)
|> Drule.strip_shyps_warning
|> zero_var_indexes |> Thm.varifyT |> Thm.compress
end;
fun export_thy thy th =
let val A_set = get_top_scope_thms thy
in
standard_some thy [] (Seq.hd ((REPEAT (FIRSTGOAL (rtac reflexive_thm))) (standard_some thy A_set th)))
end;
val export = standard o Seq.hd o (REPEAT (FIRSTGOAL (rtac reflexive_thm))) o standard;
fun Export th = export_thy (the_context ()) th;
(*Common treatment of "goal" and "prove_goal":
Return assumptions, initial proof state, and function to make result.
"atomic" indicates if the goal should be wrapped up in the function
"Goal::prop=>prop" to avoid assumptions being returned separately.
*)
fun prepare_proof atomic rths chorn =
let val {sign, t=horn,...} = rep_cterm chorn;
val _ = Term.no_dummy_patterns horn handle TERM (msg, _) => error msg;
val (_,As,B) = Logic.strip_horn(horn);
val atoms = atomic andalso
forall (fn t => not(Logic.is_implies t orelse Logic.is_all t)) As;
val (As,B) = if atoms then ([],horn) else (As,B);
val cAs = map (cterm_of sign) As;
val prems = map (rewrite_rule rths o forall_elim_vars(0) o assume) cAs;
val cB = cterm_of sign B;
val st0 = let val st = Drule.mk_triv_goal cB
in rewrite_goals_rule rths st end
(*discharges assumptions from state in the order they appear in goal;
checks (if requested) that resulting theorem is equivalent to goal. *)
fun mkresult (check,state) =
let val state = Seq.hd (flexflex_rule state)
handle THM _ => state (*smash flexflex pairs*)
val ngoals = nprems_of state
val ath = implies_intr_list cAs state
val th = ath RS Drule.rev_triv_goal
val {hyps,prop,sign=sign',...} = rep_thm th
val final_th = if (null(hyps)) then standard th else varify th
in if not check then final_th
else if not (Sign.eq_sg(sign,sign')) then !result_error_fn state
("Signature of proof state has changed!" ^
sign_error (sign,sign'))
else if ngoals>0 then !result_error_fn state
(string_of_int ngoals ^ " unsolved goals!")
else if (not (null hyps) andalso (not (Locale.in_locale hyps sign)))
then !result_error_fn state
("Additional hypotheses:\n" ^
cat_lines
(map (Sign.string_of_term sign)
(filter (fn x => (not (Locale.in_locale [x] sign)))
hyps)))
else if Pattern.matches (#tsig(Sign.rep_sg sign))
(Envir.beta_norm (term_of chorn), Envir.beta_norm prop)
then final_th
else !result_error_fn state "proved a different theorem"
end
in
if Sign.eq_sg(sign, #sign(rep_thm st0))
then (prems, st0, mkresult)
else error ("Definitions would change the proof state's signature" ^
sign_error (sign, #sign(rep_thm st0)))
end
handle THM(s,_,_) => error("prepare_proof: exception THM was raised!\n" ^ s);
(*Prints exceptions readably to users*)
fun print_sign_exn_unit sign e =
case e of
THM (msg,i,thms) =>
(writeln ("Exception THM " ^ string_of_int i ^ " raised:\n" ^ msg);
seq print_thm thms)
| THEORY (msg,thys) =>
(writeln ("Exception THEORY raised:\n" ^ msg);
seq (Pretty.writeln o Display.pretty_theory) thys)
| TERM (msg,ts) =>
(writeln ("Exception TERM raised:\n" ^ msg);
seq (writeln o Sign.string_of_term sign) ts)
| TYPE (msg,Ts,ts) =>
(writeln ("Exception TYPE raised:\n" ^ msg);
seq (writeln o Sign.string_of_typ sign) Ts;
seq (writeln o Sign.string_of_term sign) ts)
| e => raise e;
(*Prints an exception, then fails*)
fun print_sign_exn sign e = (print_sign_exn_unit sign e; raise ERROR);
(** the prove_goal.... commands
Prove theorem using the listed tactics; check it has the specified form.
Augment signature with all type assignments of goal.
Syntax is similar to "goal" command for easy keyboard use. **)
(*Version taking the goal as a cterm*)
fun prove_goalw_cterm_general check rths chorn tacsf =
let val (prems, st0, mkresult) = prepare_proof false rths chorn
val tac = EVERY (tacsf prems)
fun statef() =
(case Seq.pull (tac st0) of
Some(st,_) => st
| _ => error ("prove_goal: tactic failed"))
in mkresult (check, cond_timeit (!Library.timing) statef) end
handle e => (print_sign_exn_unit (#sign (rep_cterm chorn)) e;
writeln ("The exception above was raised for\n" ^
Display.string_of_cterm chorn); raise e);
(*Two variants: one checking the result, one not.
Neither prints runtime messages: they are for internal packages.*)
fun prove_goalw_cterm rths chorn =
setmp Library.timing false (prove_goalw_cterm_general true rths chorn)
and prove_goalw_cterm_nocheck rths chorn =
setmp Library.timing false (prove_goalw_cterm_general false rths chorn);
(*Version taking the goal as a string*)
fun prove_goalw thy rths agoal tacsf =
let val sign = Theory.sign_of thy
val chorn = read_cterm sign (agoal,propT)
in prove_goalw_cterm_general true rths chorn tacsf end
handle ERROR => error (*from read_cterm?*)
("The error(s) above occurred for " ^ quote agoal);
(*String version with no meta-rewrite-rules*)
fun prove_goal thy = prove_goalw thy [];
(*quick and dirty version (conditional)*)
fun quick_and_dirty_prove_goalw_cterm thy rews ct tacs =
prove_goalw_cterm rews ct
(if ! quick_and_dirty then (K [SkipProof.cheat_tac thy]) else tacs);
(*** Commands etc ***)
(*Return the current goal stack, if any, from undo_list*)
fun getstate() : gstack = case !undo_list of
[] => error"No current state in subgoal module"
| x::_ => x;
(*Pops the given goal stack*)
fun pop [] = error"Cannot go back past the beginning of the proof!"
| pop (pair::pairs) = (pair,pairs);
(* Print a level of the goal stack -- subject to quiet mode *)
val quiet = ref false;
fun disable_pr () = quiet := true;
fun enable_pr () = quiet := false;
fun print_top ((th, _), pairs) =
if ! quiet then ()
else ! Display.print_current_goals_fn (length pairs) (! goals_limit) th;
(*Printing can raise exceptions, so the assignment occurs last.
Can do setstate[(st,Seq.empty)] to set st as the state. *)
fun setstate newgoals =
(print_top (pop newgoals); undo_list := newgoals :: !undo_list);
(*Given a proof state transformation, return a command that updates
the goal stack*)
fun make_command com = setstate (com (pop (getstate())));
(*Apply a function on proof states to the current goal stack*)
fun apply_fun f = f (pop(getstate()));
(*Return the top theorem, representing the proof state*)
fun topthm () = apply_fun (fn ((th,_), _) => th);
(*Return the final result. *)
fun result () = !curr_mkresult (true, topthm());
(*Return the result UNCHECKED that it equals the goal -- for synthesis,
answer extraction, or other instantiation of Vars *)
fun uresult () = !curr_mkresult (false, topthm());
(*Get subgoal i from goal stack*)
fun getgoal i = List.nth (prems_of (topthm()), i-1)
handle Subscript => error"getgoal: Goal number out of range";
(*Return subgoal i's hypotheses as meta-level assumptions.
For debugging uses of METAHYPS*)
local exception GETHYPS of thm list
in
fun gethyps i =
(METAHYPS (fn hyps => raise (GETHYPS hyps)) i (topthm()); [])
handle GETHYPS hyps => hyps
end;
(*Which thms could apply to goal i? (debugs tactics involving filter_thms) *)
fun filter_goal could ths i = filter_thms could (999, getgoal i, ths);
(*For inspecting earlier levels of the backward proof*)
fun chop_level n (pair,pairs) =
let val level = length pairs
in if n<0 andalso ~n <= level
then List.drop (pair::pairs, ~n)
else if 0<=n andalso n<= level
then List.drop (pair::pairs, level - n)
else error ("Level number must lie between 0 and " ^
string_of_int level)
end;
(*Print the given level of the proof; prlev ~1 prints previous level*)
fun prlev n = (enable_pr (); apply_fun (print_top o pop o (chop_level n)));
fun pr () = (enable_pr (); apply_fun print_top);
(*Set goals_limit and print again*)
fun prlim n = (goals_limit:=n; pr());
(** the goal.... commands
Read main goal. Set global variables curr_prems, curr_mkresult.
Initial subgoal and premises are rewritten using rths. **)
(*Version taking the goal as a cterm; if you have a term t and theory thy, use
goalw_cterm rths (cterm_of (Theory.sign_of thy) t); *)
fun agoalw_cterm atomic rths chorn =
let val (prems, st0, mkresult) = prepare_proof atomic rths chorn
in undo_list := [];
setstate [ (st0, Seq.empty) ];
curr_prems := prems;
curr_mkresult := mkresult;
prems
end;
val goalw_cterm = agoalw_cterm false;
(*Version taking the goal as a string*)
fun agoalw atomic thy rths agoal =
agoalw_cterm atomic rths (Locale.read_cterm(Theory.sign_of thy)(agoal,propT))
handle ERROR => error (*from type_assign, etc via prepare_proof*)
("The error(s) above occurred for " ^ quote agoal);
val goalw = agoalw false;
(*String version with no meta-rewrite-rules*)
fun agoal atomic thy = agoalw atomic thy [];
val goal = agoal false;
(*now the versions that wrap the goal up in `Goal' to make it atomic*)
val atomic_goalw = agoalw true;
val atomic_goal = agoal true;
(*implicit context versions*)
fun Goal s = atomic_goal (Context.the_context ()) s;
fun Goalw thms s = atomic_goalw (Context.the_context ()) thms s;
(*Proof step "by" the given tactic -- apply tactic to the proof state*)
fun by_com tac ((th,ths), pairs) : gstack =
(case Seq.pull(tac th) of
None => error"by: tactic failed"
| Some(th2,ths2) =>
(if eq_thm(th,th2)
then warning "Warning: same as previous level"
else if eq_thm_sg(th,th2) then ()
else warning ("Warning: signature of proof state has changed" ^
sign_error (#sign(rep_thm th), #sign(rep_thm th2)));
((th2,ths2)::(th,ths)::pairs)));
fun by tac = cond_timeit (!Library.timing)
(fn() => make_command (by_com tac));
(* byev[tac1,...,tacn] applies tac1 THEN ... THEN tacn.
Good for debugging proofs involving prove_goal.*)
val byev = by o EVERY;
(*Backtracking means find an alternative result from a tactic.
If none at this level, try earlier levels*)
fun backtrack [] = error"back: no alternatives"
| backtrack ((th,thstr) :: pairs) =
(case Seq.pull thstr of
None => (writeln"Going back a level..."; backtrack pairs)
| Some(th2,thstr2) =>
(if eq_thm(th,th2)
then warning "Warning: same as previous choice at this level"
else if eq_thm_sg(th,th2) then ()
else warning "Warning: signature of proof state has changed";
(th2,thstr2)::pairs));
fun back() = setstate (backtrack (getstate()));
(*Chop back to previous level of the proof*)
fun choplev n = make_command (chop_level n);
(*Chopping back the goal stack*)
fun chop () = make_command (fn (_,pairs) => pairs);
(*Restore the previous proof state; discard current state. *)
fun undo() = case !undo_list of
[] => error"No proof state"
| [_] => error"Already at initial state"
| _::newundo => (undo_list := newundo; pr()) ;
(*** Managing the proof stack ***)
fun save_proof() = Proof(!undo_list, !curr_prems, !curr_mkresult);
fun restore_proof(Proof(ul,prems,mk)) =
(undo_list:= ul; curr_prems:= prems; curr_mkresult := mk; prems);
fun top_proof() = case !proofstack of
[] => error("Stack of proof attempts is empty!")
| p::ps => (p,ps);
(* push a copy of the current proof state on to the stack *)
fun push_proof() = (proofstack := (save_proof() :: !proofstack));
(* discard the top proof state of the stack *)
fun pop_proof() =
let val (p,ps) = top_proof()
val prems = restore_proof p
in proofstack := ps; pr(); prems end;
(* rotate the stack so that the top element goes to the bottom *)
fun rotate_proof() = let val (p,ps) = top_proof()
in proofstack := ps@[save_proof()];
restore_proof p;
pr();
!curr_prems
end;
(** Shortcuts for commonly-used tactics **)
fun bws rls = by (rewrite_goals_tac rls);
fun bw rl = bws [rl];
fun brs rls i = by (resolve_tac rls i);
fun br rl = brs [rl];
fun bes rls i = by (eresolve_tac rls i);
fun be rl = bes [rl];
fun bds rls i = by (dresolve_tac rls i);
fun bd rl = bds [rl];
fun ba i = by (assume_tac i);
fun ren str i = by (rename_tac str i);
(** Shortcuts to work on the first applicable subgoal **)
fun frs rls = by (FIRSTGOAL (trace_goalno_tac (resolve_tac rls)));
fun fr rl = frs [rl];
fun fes rls = by (FIRSTGOAL (trace_goalno_tac (eresolve_tac rls)));
fun fe rl = fes [rl];
fun fds rls = by (FIRSTGOAL (trace_goalno_tac (dresolve_tac rls)));
fun fd rl = fds [rl];
fun fa() = by (FIRSTGOAL (trace_goalno_tac assume_tac));
(** Reading and printing terms wrt the current theory **)
fun top_sg() = #sign(rep_thm(topthm()));
fun read s = term_of (read_cterm (top_sg()) (s, TypeInfer.logicT));
(*Print a term under the current signature of the proof state*)
fun prin t = writeln (Sign.string_of_term (top_sg()) t);
fun printyp T = writeln (Sign.string_of_typ (top_sg()) T);
fun pprint_term t = Sign.pprint_term (top_sg()) t;
fun pprint_typ T = Sign.pprint_typ (top_sg()) T;
(*Prints exceptions nicely at top level;
raises the exception in order to have a polymorphic type!*)
fun print_exn e = (print_sign_exn_unit (top_sg()) e; raise e);
(** theorem database operations **)
(* storing *)
fun bind_thm (name, thm) = ThmDatabase.ml_store_thm (name, standard thm);
fun bind_thms (name, thms) = ThmDatabase.ml_store_thms (name, map standard thms);
fun qed name = ThmDatabase.ml_store_thm (name, result ());
fun qed_goal name thy goal tacsf = ThmDatabase.ml_store_thm (name, prove_goal thy goal tacsf);
fun qed_goalw name thy rews goal tacsf =
ThmDatabase.ml_store_thm (name, prove_goalw thy rews goal tacsf);
fun qed_spec_mp name =
ThmDatabase.ml_store_thm (name, ObjectLogic.rulify_no_asm (result ()));
fun qed_goal_spec_mp name thy s p =
bind_thm (name, ObjectLogic.rulify_no_asm (prove_goal thy s p));
fun qed_goalw_spec_mp name thy defs s p =
bind_thm (name, ObjectLogic.rulify_no_asm (prove_goalw thy defs s p));
fun no_qed () = ();
(* retrieval *)
fun theory_of_goal () = ThyInfo.theory_of_sign (Thm.sign_of_thm (topthm ()));
fun thms_containing raw_consts =
let
val thy = theory_of_goal ();
val consts = map (Sign.intern_const (Theory.sign_of thy)) raw_consts;
in ThmDatabase.thms_containing thy consts end;
(*top_const: main constant, ignoring Trueprop*)
fun top_const (_ $ t) = (case head_of t of Const (c, _) => Some c | _ => None)
| top_const _ = None;
val intro_const = top_const o concl_of;
fun elim_const thm = case prems_of thm of [] => None | p::_ => top_const p;
(* In case faster access is necessary, the thm db should provide special
functions
index_intros, index_elims: string -> (string * thm) list
where thm [| A1 ; ...; An |] ==> B is returned by
- index_intros c if B is of the form c t1 ... tn
- index_elims c if A1 is of the form c t1 ... tn
*)
(* could be provided by thm db *)
fun index_intros c =
let fun topc(_,thm) = intro_const thm = Some(c);
val named_thms = ThmDatabase.thms_containing (theory_of_goal ()) [c]
in filter topc named_thms end;
(* could be provided by thm db *)
fun index_elims c =
let fun topc(_,thm) = elim_const thm = Some(c);
val named_thms = ThmDatabase.thms_containing (theory_of_goal ()) [c]
in filter topc named_thms end;
(*assume that parameters have unique names; reverse them for substitution*)
fun goal_params i =
let val gi = getgoal i
val rfrees = rev(map Free (Logic.strip_params gi))
in (gi,rfrees) end;
fun concl_of_goal i =
let val (gi,rfrees) = goal_params i
val B = Logic.strip_assums_concl gi
in subst_bounds(rfrees,B) end;
fun prems_of_goal i =
let val (gi,rfrees) = goal_params i
val As = Logic.strip_assums_hyp gi
in map (fn A => subst_bounds(rfrees,A)) As end;
(*returns all those named_thms whose subterm extracted by extract can be
instantiated to obj; the list is sorted according to the number of premises
and the size of the required substitution.*)
fun select_match(obj, signobj, named_thms, extract) =
let fun matches(prop, tsig) =
case extract prop of
None => false
| Some pat => Pattern.matches tsig (pat, obj);
fun substsize(prop, tsig) =
let val Some pat = extract prop
val (_,subst) = Pattern.match tsig (pat,obj)
in foldl op+
(0, map (fn (_,t) => size_of_term t) subst)
end
fun thm_ord ((p0,s0,_),(p1,s1,_)) =
prod_ord (int_ord o pairself (fn 0 => 0 | x => 1)) int_ord ((p0,s0),(p1,s1));
fun select((p as (_,thm))::named_thms, sels) =
let val {prop, sign, ...} = rep_thm thm
in select(named_thms,
if Sign.subsig(sign, signobj) andalso
matches(prop,#tsig(Sign.rep_sg signobj))
then
(nprems_of thm,substsize(prop,#tsig(Sign.rep_sg signobj)),p)::sels
else sels)
end
| select([],sels) = sels
in map (fn (_,_,t) => t) (sort thm_ord (select(named_thms, []))) end;
fun find_matching(prop,sign,index,extract) =
(case top_const prop of
Some c => select_match(prop,sign,index c,extract)
| _ => []);
fun find_intros(prop,sign) =
find_matching(prop,sign,index_intros,Some o Logic.strip_imp_concl);
fun find_elims sign prop =
let fun major prop = case Logic.strip_imp_prems prop of
[] => None | p::_ => Some p
in find_matching(prop,sign,index_elims,major) end;
fun findI i = find_intros(concl_of_goal i,#sign(rep_thm(topthm())));
fun findEs i =
let fun eq_nth((n1,th1),(n2,th2)) = n1=n2 andalso eq_thm(th1,th2);
val sign = #sign(rep_thm(topthm()))
val thmss = map (find_elims sign) (prems_of_goal i)
in foldl (gen_union eq_nth) ([],thmss) end;
fun findE i j =
let val sign = #sign(rep_thm(topthm()))
in find_elims sign (nth_elem(j-1, prems_of_goal i)) end;
end;
open Goals;