1 (* Title: HOL/Library/reflection.ML
2 Author: Amine Chaieb, TU Muenchen
4 A trial for automatical reification.
9 val genreify_tac: Proof.context -> thm list -> term option -> int -> tactic
10 val reflection_tac: Proof.context -> thm list -> thm list -> term option -> int -> tactic
11 val gen_reflection_tac: Proof.context -> (cterm -> thm)
12 -> thm list -> thm list -> term option -> int -> tactic
13 val genreif : Proof.context -> thm list -> term -> thm
16 structure Reflection : REFLECTION =
19 val ext2 = @{thm ext2};
20 val nth_Cons_0 = @{thm nth_Cons_0};
21 val nth_Cons_Suc = @{thm nth_Cons_Suc};
23 (* Make a congruence rule out of a defining equation for the interpretation *)
24 (* th is one defining equation of f, i.e.
25 th is "f (Cp ?t1 ... ?tn) = P(f ?t1, .., f ?tn)" *)
26 (* Cp is a constructor pattern and P is a pattern *)
29 [|?A1 = f ?t1 ; .. ; ?An= f ?tn |] ==> P (?A1, .., ?An) = f (Cp ?t1 .. ?tn) *)
30 (* + the a list of names of the A1 .. An, Those are fresh in the ctxt*)
32 fun mk_congeq ctxt fs th =
34 val (f as Const(fN,fT)) = th |> prop_of |> HOLogic.dest_Trueprop |> HOLogic.dest_eq
35 |> fst |> strip_comb |> fst
36 val thy = Proof_Context.theory_of ctxt
37 val cert = Thm.cterm_of thy
38 val (((_,_),[th']), ctxt') = Variable.import true [th] ctxt
39 val (lhs, rhs) = HOLogic.dest_eq (HOLogic.dest_Trueprop (Thm.prop_of th'))
40 fun add_fterms (t as t1 $ t2) =
41 if exists (fn f => Term.could_unify (t |> strip_comb |> fst, f)) fs then insert (op aconv) t
42 else add_fterms t1 #> add_fterms t2
43 | add_fterms (t as Abs(xn,xT,t')) =
44 if exists_Const (fn (c, _) => c = fN) t then (fn _ => [t]) else (fn _ => [])
46 val fterms = add_fterms rhs []
47 val (xs, ctxt'') = Variable.variant_fixes (replicate (length fterms) "x") ctxt'
48 val tys = map fastype_of fterms
49 val vs = map Free (xs ~~ tys)
50 val env = fterms ~~ vs
52 fun replace_fterms (t as t1 $ t2) =
53 (case AList.lookup (op aconv) env t of
55 | NONE => replace_fterms t1 $ replace_fterms t2)
56 | replace_fterms t = (case AList.lookup (op aconv) env t of
60 fun mk_def (Abs(x,xT,t),v) = HOLogic.mk_Trueprop ((HOLogic.all_const xT)$ Abs(x,xT,HOLogic.mk_eq(v$(Bound 0), t)))
61 | mk_def (t, v) = HOLogic.mk_Trueprop (HOLogic.mk_eq (v, t))
62 fun tryext x = (x RS ext2 handle THM _ => x)
63 val cong = (Goal.prove ctxt'' [] (map mk_def env)
64 (HOLogic.mk_Trueprop (HOLogic.mk_eq (lhs, replace_fterms rhs)))
65 (fn x => Local_Defs.unfold_tac (#context x) (map tryext (#prems x))
66 THEN rtac th' 1)) RS sym
68 val (cong' :: vars') =
69 Variable.export ctxt'' ctxt (cong :: map (Drule.mk_term o cert) vs)
70 val vs' = map (fst o fst o Term.dest_Var o Thm.term_of o Drule.dest_term) vars'
73 (* congs is a list of pairs (P,th) where th is a theorem for *)
74 (* [| f p1 = A1; ...; f pn = An|] ==> f (C p1 .. pn) = P *)
75 val FWD = curry (op OF);
78 exception REIF of string;
80 fun dest_listT (Type (@{type_name "list"}, [T])) = T;
85 let val @{term "Trueprop"}$(Const (@{const_name HOL.eq},_) $l$_) = concl_of th
87 val (yes,no) = List.partition P congs
90 fun genreif ctxt raw_eqs t =
94 val tt = HOLogic.listT (fastype_of t)
96 (case AList.lookup Type.could_unify bds tt of
97 NONE => error "index_of : type not found in environements!"
100 val i = find_index (fn t' => t' = t) tats
101 val j = find_index (fn t' => t' = t) tbs
104 then (length tbs + length tats,
105 AList.update Type.could_unify (tt,(tbs,tats@[t])) bds)
106 else (i, bds) else (j, bds))
110 (* Generic decomp for reification : matches the actual term with the
111 rhs of one cong rule. The result of the matching guides the
112 proof synthesis: The matches of the introduced Variables A1 .. An are
113 processed recursively
114 The rest is instantiated in the cong rule,i.e. no reification is needed *)
116 (* da is the decomposition for atoms, ie. it returns ([],g) where g
117 returns the right instance f (AtC n) = t , where AtC is the Atoms
118 constructor and n is the number of the atom corresponding to t *)
119 fun decomp_genreif da cgns (t,ctxt) bds =
121 val thy = Proof_Context.theory_of ctxt
122 val cert = cterm_of thy
123 fun tryabsdecomp (s,ctxt) bds =
127 val ([xn],ctxt') = Variable.variant_fixes ["x"] ctxt
128 val (xn,ta) = Syntax_Trans.variant_abs (xn,xT,ta) (* FIXME !? *)
130 val bds = (case AList.lookup Type.could_unify bds (HOLogic.listT xT)
131 of NONE => error "tryabsdecomp: Type not found in the Environement"
133 (AList.update Type.could_unify (HOLogic.listT xT, ((x::bsT), atsT)) bds))
136 (hd (Variable.export ctxt' ctxt [(Thm.forall_intr (cert x) th) COMP allI]),
137 let val (bsT,asT) = the(AList.lookup Type.could_unify bds (HOLogic.listT xT))
138 in AList.update Type.could_unify (HOLogic.listT xT,(tl bsT,asT)) bds
142 | _ => da (s,ctxt) bds)
145 [] => tryabsdecomp (t,ctxt) bds
146 | ((vns,cong)::congs) =>
148 val cert = cterm_of thy
149 val certy = ctyp_of thy
152 ((fst o HOLogic.dest_eq o HOLogic.dest_Trueprop) (concl_of cong), t)
153 (Vartab.empty, Vartab.empty)
154 val (fnvs,invs) = List.partition (fn ((vn,_),_) => member (op =) vns vn) (Vartab.dest tmenv)
156 (map (snd o snd) fnvs,
157 map (fn ((vn,vi),(tT,t)) => (cert(Var ((vn,vi),tT)), cert t)) invs)
158 val ctyenv = map (fn ((vn,vi),(s,ty)) => (certy (TVar((vn,vi),s)), certy ty)) (Vartab.dest tyenv)
159 in ((fts ~~ (replicate (length fts) ctxt),
160 Library.apfst (FWD (Drule.instantiate_normalize (ctyenv, its) cong))), bds)
161 end handle Pattern.MATCH => decomp_genreif da congs (t,ctxt) bds))
164 (* looks for the atoms equation and instantiates it with the right number *)
165 fun mk_decompatom eqs (t,ctxt) bds = (([], fn (_, bds) =>
167 val tT = fastype_of t
170 val rhs = eq |> prop_of |> HOLogic.dest_Trueprop |> HOLogic.dest_eq |> snd
172 (fn (n,ty) => n = @{const_name "List.nth"}
174 AList.defined Type.could_unify bds (domain_type ty)) rhs
175 andalso Type.could_unify (fastype_of rhs, tT)
180 Const(@{const_name "List.nth"},_)$vs$n => insert (fn ((a,_),(b,_)) => a aconv b) (t,(vs,n)) acc
181 | t1$t2 => get_nths t1 (get_nths t2 acc)
182 | Abs(_,_,t') => get_nths t' acc
186 tryeqs [] bds = error "Can not find the atoms equation"
187 | tryeqs (eq::eqs) bds = ((
189 val rhs = eq |> prop_of |> HOLogic.dest_Trueprop |> HOLogic.dest_eq |> snd
190 val nths = get_nths rhs []
191 val (vss,ns) = fold_rev (fn (_,(vs,n)) => fn (vss,ns) =>
192 (insert (op aconv) vs vss, insert (op aconv) n ns)) nths ([],[])
193 val (vsns, ctxt') = Variable.variant_fixes (replicate (length vss) "vs") ctxt
194 val (xns, ctxt'') = Variable.variant_fixes (replicate (length nths) "x") ctxt'
195 val thy = Proof_Context.theory_of ctxt''
196 val cert = cterm_of thy
197 val certT = ctyp_of thy
198 val vsns_map = vss ~~ vsns
199 val xns_map = (fst (split_list nths)) ~~ xns
200 val subst = map (fn (nt, xn) => (nt, Var ((xn,0), fastype_of nt))) xns_map
201 val rhs_P = subst_free subst rhs
202 val (tyenv, tmenv) = Pattern.match thy (rhs_P, t) (Vartab.empty, Vartab.empty)
203 val sbst = Envir.subst_term (tyenv, tmenv)
204 val sbsT = Envir.subst_type tyenv
205 val subst_ty = map (fn (n,(s,t)) => (certT (TVar (n, s)), certT t))
207 val tml = Vartab.dest tmenv
208 val t's = map (fn xn => snd (the (AList.lookup (op =) tml (xn,0)))) xns (* FIXME : Express with sbst*)
209 val (subst_ns, bds) = fold_map
210 (fn (Const _ $ vs $ n, Var (xn0,T)) => fn bds =>
212 val name = snd (the (AList.lookup (op =) tml xn0))
213 val (idx, bds) = index_of name bds
214 in ((cert n, idx |> (HOLogic.mk_nat #> cert)), bds) end) subst bds
217 fun ty (Const _ $ (vs as Var (vsn,lT)) $ n, Var (xn0,T)) = (certT T, certT (sbsT T))
218 fun h (Const _ $ (vs as Var (vsn,lT)) $ n, Var (xn0,T)) =
220 val cns = sbst (Const(@{const_name "List.Cons"}, T --> lT --> lT))
222 val (bsT,asT) = the (AList.lookup Type.could_unify bds lT)
223 val vsn = the (AList.lookup (op =) vsns_map vs)
224 val cvs = cert (fold_rev (fn x => fn xs => cns$x$xs) bsT (Free (vsn, lT')))
225 in (cert vs, cvs) end
227 val cts = map (fn ((vn,vi),(tT,t)) => (cert(Var ((vn,vi),tT)), cert t))
228 (fold (AList.delete (fn (((a: string),_),(b,_)) => a = b))
229 (map (fn n => (n,0)) xns) tml)
231 let val ih = Drule.cterm_rule (Thm.instantiate (subst_ty,[]))
232 in map (fn (v,t) => (ih v, ih t)) (subst_ns@subst_vs@cts) end
233 val th = (Drule.instantiate_normalize (subst_ty, substt) eq) RS sym
234 in (hd (Variable.export ctxt'' ctxt [th]), bds) end)
235 handle Pattern.MATCH => tryeqs eqs bds)
236 in tryeqs (filter isat eqs) bds end), bds);
238 (* Generic reification procedure: *)
239 (* creates all needed cong rules and then just uses the theorem synthesis *)
241 fun mk_congs ctxt raw_eqs =
243 val fs = fold_rev (fn eq =>
244 insert (op =) (eq |> prop_of |> HOLogic.dest_Trueprop
245 |> HOLogic.dest_eq |> fst |> strip_comb
247 val tys = fold_rev (fn f => fold (insert (op =)) (f |> fastype_of |> binder_types |> tl)
249 val (vs, ctxt') = Variable.variant_fixes (replicate (length tys) "vs") ctxt
250 val thy = Proof_Context.theory_of ctxt'
251 val cert = cterm_of thy
252 val vstys = map (fn (t,v) => (t,SOME (cert (Free(v,t)))))
254 val is_Var = can dest_Var
257 val subst = map (fn (v as Var(n,t)) => (cert v, (the o the) (AList.lookup (op =) vstys t)))
259 in Thm.instantiate ([],subst) eq
262 val bds = AList.make (fn _ => ([],[])) tys
263 val eqs = map (fn eq => eq |> prop_of |> HOLogic.dest_Trueprop
264 |> HOLogic.dest_eq |> fst |> strip_comb |> snd |> tl
265 |> (insteq eq)) raw_eqs
266 val (ps,congs) = split_list (map (mk_congeq ctxt' fs) eqs)
267 in (ps ~~ (Variable.export ctxt' ctxt congs), bds)
270 val (congs, bds) = mk_congs ctxt raw_eqs
271 val congs = rearrange congs
272 val (th, bds) = divide_and_conquer' (decomp_genreif (mk_decompatom raw_eqs) congs) (t,ctxt) bds
273 fun is_listVar (Var (_,t)) = can dest_listT t
274 | is_listVar _ = false
275 val vars = th |> prop_of |> HOLogic.dest_Trueprop |> HOLogic.dest_eq |> snd
276 |> strip_comb |> snd |> filter is_listVar
277 val cert = cterm_of (Proof_Context.theory_of ctxt)
278 val cvs = map (fn (v as Var(n,t)) => (cert v,
279 the (AList.lookup Type.could_unify bds t) |> snd |> HOLogic.mk_list (dest_listT t) |> cert)) vars
280 val th' = Drule.instantiate_normalize ([], cvs) th
281 val t' = (fst o HOLogic.dest_eq o HOLogic.dest_Trueprop o prop_of) th'
282 val th'' = Goal.prove ctxt [] [] (HOLogic.mk_Trueprop (HOLogic.mk_eq (t, t')))
283 (fn _ => simp_tac (simpset_of ctxt) 1)
284 in FWD trans [th'',th']
288 fun genreflect ctxt conv corr_thms raw_eqs t =
290 val reifth = genreif ctxt raw_eqs t
291 fun trytrans [] = error "No suitable correctness theorem found"
292 | trytrans (th::ths) =
293 (FWD trans [reifth, th RS sym] handle THM _ => trytrans ths)
294 val th = trytrans corr_thms
295 val ft = (Thm.dest_arg1 o Thm.dest_arg o Thm.dest_arg o cprop_of) th
297 in simplify (HOL_basic_ss addsimps raw_eqs addsimps [nth_Cons_0, nth_Cons_Suc])
298 (simplify (HOL_basic_ss addsimps [rth]) th)
301 fun genreify_tac ctxt eqs to = SUBGOAL (fn (goal, i) =>
303 val t = (case to of NONE => HOLogic.dest_Trueprop goal | SOME x => x)
304 val th = genreif ctxt eqs t RS ssubst
307 (* Reflection calls reification and uses the correctness *)
308 (* theorem assumed to be the head of the list *)
309 fun gen_reflection_tac ctxt conv corr_thms raw_eqs to = SUBGOAL (fn (goal, i) =>
311 val t = (case to of NONE => HOLogic.dest_Trueprop goal | SOME x => x)
312 val th = genreflect ctxt conv corr_thms raw_eqs t RS ssubst
313 in rtac th i THEN TRY (rtac TrueI i) end); (* FIXME THEN_ALL_NEW !? *)
315 fun reflection_tac ctxt = gen_reflection_tac ctxt (Codegen.evaluation_conv ctxt);
316 (*FIXME why Codegen.evaluation_conv? very specific...*)