--- a/src/Provers/hypsubst.ML Wed Nov 02 10:45:14 1994 +0100
+++ b/src/Provers/hypsubst.ML Wed Nov 02 12:44:03 1994 +0100
@@ -8,12 +8,11 @@
signature HYPSUBST_DATA =
sig
- val dest_eq: term -> term*term
- val imp_intr: thm (* (P ==> Q) ==> P-->Q *)
- val rev_cut_eq: thm (* [| a=b; a=b ==> R |] ==> R *)
- val rev_mp: thm (* [| P; P-->Q |] ==> Q *)
- val subst: thm (* [| a=b; P(a) |] ==> P(b) *)
- val sym: thm (* a=b ==> b=a *)
+ val dest_eq : term -> term*term
+ val imp_intr : thm (* (P ==> Q) ==> P-->Q *)
+ val rev_mp : thm (* [| P; P-->Q |] ==> Q *)
+ val subst : thm (* [| a=b; P(a) |] ==> P(b) *)
+ val sym : thm (* a=b ==> b=a *)
end;
signature HYPSUBST =
@@ -21,9 +20,8 @@
val bound_hyp_subst_tac : int -> tactic
val hyp_subst_tac : int -> tactic
(*exported purely for debugging purposes*)
- val eq_var : bool -> term -> term * thm
- val inspect_pair : bool -> term * term -> term * thm
- val liftvar : int -> typ list -> term
+ val eq_var : bool -> term -> int * thm
+ val inspect_pair : bool -> term * term -> thm
end;
functor HypsubstFun(Data: HYPSUBST_DATA): HYPSUBST =
@@ -35,14 +33,6 @@
| REPEATN n tac = Tactic(fn state =>
tapply(tac THEN REPEATN (n-1) tac, state));
-local
- val T = case #1 (types_sorts rev_cut_eq) ("a",0) of
- Some T => T
- | None => error"No such variable in rev_cut_eq"
-in
- fun liftvar inc paramTs = Var(("a",inc), paramTs ---> incr_tvar inc T);
-end;
-
exception EQ_VAR;
fun loose (i,t) = 0 mem add_loose_bnos(t,i,[]);
@@ -55,50 +45,39 @@
fun inspect_pair bnd (t,u) =
case (Pattern.eta_contract t, Pattern.eta_contract u) of
(Bound i, _) => if loose(i,u) then raise Match
- else (t, asm_rl)
+ else sym (*eliminates t*)
| (_, Bound i) => if loose(i,t) then raise Match
- else (u, sym)
+ else asm_rl (*eliminates u*)
| (Free _, _) => if bnd orelse Logic.occs(t,u) then raise Match
- else (t, asm_rl)
+ else sym (*eliminates t*)
| (_, Free _) => if bnd orelse Logic.occs(u,t) then raise Match
- else (u, sym)
+ else asm_rl (*eliminates u*)
| _ => raise Match;
- (* Extracts the name of the variable on the left (resp. right) of an equality
- assumption. Returns the rule asm_rl (resp. sym). *)
-fun eq_var bnd (Const("all",_) $ Abs(_,_,t)) = eq_var bnd t
- | eq_var bnd (Const("==>",_) $ A $ B) =
- (inspect_pair bnd (dest_eq A)
- (*Match comes from inspect_pair or dest_eq*)
- handle Match => eq_var bnd B)
- | eq_var bnd _ = raise EQ_VAR;
-
-(*Lift and instantiate a rule wrt the given state and subgoal number *)
-fun lift_instpair (state, i, t, rule) =
- let val {maxidx,sign,...} = rep_thm state
- val (_, _, Bi, _) = dest_state(state,i)
- val params = Logic.strip_params Bi
- val var = liftvar (maxidx+1) (map #2 params)
- and u = Unify.rlist_abs(rev params, t)
- and cterm = cterm_of sign
- in cterm_instantiate [(cterm var, cterm u)] (lift_rule (state,i) rule)
- end;
-
-fun eres_instpair_tac t rule i = STATE (fn state =>
- compose_tac (true, lift_instpair (state, i, t, rule),
- length(prems_of rule)) i);
-
-val ssubst = sym RS subst;
+(*Locates a substitutable variable on the left (resp. right) of an equality
+ assumption. Returns the number of intervening assumptions, paried with
+ the rule asm_rl (resp. sym). *)
+fun eq_var bnd =
+ let fun eq_var_aux k (Const("all",_) $ Abs(_,_,t)) = eq_var_aux k t
+ | eq_var_aux k (Const("==>",_) $ A $ B) =
+ ((k, inspect_pair bnd (dest_eq A))
+ (*Exception Match comes from inspect_pair or dest_eq*)
+ handle Match => eq_var_aux (k+1) B)
+ | eq_var_aux k _ = raise EQ_VAR
+ in eq_var_aux 0 end;
(*Select a suitable equality assumption and substitute throughout the subgoal
Replaces only Bound variables if bnd is true*)
fun gen_hyp_subst_tac bnd i = DETERM (STATE(fn state =>
let val (_,_,Bi,_) = dest_state(state,i)
val n = length(Logic.strip_assums_hyp Bi) - 1
- val (t,symopt) = eq_var bnd Bi
- in eres_instpair_tac t (symopt RS rev_cut_eq) i THEN
- REPEATN n (etac rev_mp i) THEN
- etac ssubst i THEN REPEATN n (rtac imp_intr i)
+ val (k,symopt) = eq_var bnd Bi
+ in
+ EVERY [REPEATN k (etac rev_mp i),
+ etac revcut_rl i,
+ REPEATN (n-k) (etac rev_mp i),
+ etac (symopt RS subst) i,
+ REPEATN n (rtac imp_intr i)]
end
handle THM _ => no_tac | EQ_VAR => no_tac));