(* Title: HOL/Tools/datatype_abs_proofs.ML
Author: Stefan Berghofer, TU Muenchen
Proofs and defintions independent of concrete representation
of datatypes (i.e. requiring only abstract properties such as
injectivity / distinctness of constructors and induction)
- case distinction (exhaustion) theorems
- characteristic equations for primrec combinators
- characteristic equations for case combinators
- equations for splitting "P (case ...)" expressions
- "nchotomy" and "case_cong" theorems for TFL
*)
signature DATATYPE_ABS_PROOFS =
sig
val prove_casedist_thms : string list ->
DatatypeAux.descr list -> (string * sort) list -> thm ->
attribute list -> theory -> thm list * theory
val prove_primrec_thms : bool -> string list ->
DatatypeAux.descr list -> (string * sort) list ->
DatatypeAux.datatype_info Symtab.table -> thm list list -> thm list list ->
simpset -> thm -> theory -> (string list * thm list) * theory
val prove_case_thms : bool -> string list ->
DatatypeAux.descr list -> (string * sort) list ->
string list -> thm list -> theory -> (thm list list * string list) * theory
val prove_split_thms : string list ->
DatatypeAux.descr list -> (string * sort) list ->
thm list list -> thm list list -> thm list -> thm list list -> theory ->
(thm * thm) list * theory
val prove_nchotomys : string list -> DatatypeAux.descr list ->
(string * sort) list -> thm list -> theory -> thm list * theory
val prove_weak_case_congs : string list -> DatatypeAux.descr list ->
(string * sort) list -> theory -> thm list * theory
val prove_case_congs : string list ->
DatatypeAux.descr list -> (string * sort) list ->
thm list -> thm list list -> theory -> thm list * theory
end;
structure DatatypeAbsProofs: DATATYPE_ABS_PROOFS =
struct
open DatatypeAux;
(************************ case distinction theorems ***************************)
fun prove_casedist_thms new_type_names descr sorts induct case_names_exhausts thy =
let
val _ = message "Proving case distinction theorems ...";
val descr' = List.concat descr;
val recTs = get_rec_types descr' sorts;
val newTs = Library.take (length (hd descr), recTs);
val {maxidx, ...} = rep_thm induct;
val induct_Ps = map head_of (HOLogic.dest_conj (HOLogic.dest_Trueprop (concl_of induct)));
fun prove_casedist_thm ((i, t), T) =
let
val dummyPs = map (fn (Var (_, Type (_, [T', T'']))) =>
Abs ("z", T', Const ("True", T''))) induct_Ps;
val P = Abs ("z", T, HOLogic.imp $ HOLogic.mk_eq (Var (("a", maxidx+1), T), Bound 0) $
Var (("P", 0), HOLogic.boolT))
val insts = Library.take (i, dummyPs) @ (P::(Library.drop (i + 1, dummyPs)));
val cert = cterm_of thy;
val insts' = (map cert induct_Ps) ~~ (map cert insts);
val induct' = refl RS ((List.nth
(split_conj_thm (cterm_instantiate insts' induct), i)) RSN (2, rev_mp))
in
SkipProof.prove_global thy [] (Logic.strip_imp_prems t) (Logic.strip_imp_concl t)
(fn {prems, ...} => EVERY
[rtac induct' 1,
REPEAT (rtac TrueI 1),
REPEAT ((rtac impI 1) THEN (eresolve_tac prems 1)),
REPEAT (rtac TrueI 1)])
end;
val casedist_thms = map prove_casedist_thm ((0 upto (length newTs - 1)) ~~
(DatatypeProp.make_casedists descr sorts) ~~ newTs)
in
thy
|> store_thms_atts "exhaust" new_type_names (map single case_names_exhausts) casedist_thms
end;
(*************************** primrec combinators ******************************)
fun prove_primrec_thms flat_names new_type_names descr sorts
(dt_info : datatype_info Symtab.table) constr_inject dist_rewrites dist_ss induct thy =
let
val _ = message "Constructing primrec combinators ...";
val big_name = space_implode "_" new_type_names;
val thy0 = add_path flat_names big_name thy;
val descr' = List.concat descr;
val recTs = get_rec_types descr' sorts;
val used = List.foldr OldTerm.add_typ_tfree_names [] recTs;
val newTs = Library.take (length (hd descr), recTs);
val induct_Ps = map head_of (HOLogic.dest_conj (HOLogic.dest_Trueprop (concl_of induct)));
val big_rec_name' = big_name ^ "_rec_set";
val rec_set_names' =
if length descr' = 1 then [big_rec_name'] else
map ((curry (op ^) (big_rec_name' ^ "_")) o string_of_int)
(1 upto (length descr'));
val rec_set_names = map (Sign.full_bname thy0) rec_set_names';
val (rec_result_Ts, reccomb_fn_Ts) = DatatypeProp.make_primrec_Ts descr sorts used;
val rec_set_Ts = map (fn (T1, T2) =>
reccomb_fn_Ts @ [T1, T2] ---> HOLogic.boolT) (recTs ~~ rec_result_Ts);
val rec_fns = map (uncurry (mk_Free "f"))
(reccomb_fn_Ts ~~ (1 upto (length reccomb_fn_Ts)));
val rec_sets' = map (fn c => list_comb (Free c, rec_fns))
(rec_set_names' ~~ rec_set_Ts);
val rec_sets = map (fn c => list_comb (Const c, rec_fns))
(rec_set_names ~~ rec_set_Ts);
(* introduction rules for graph of primrec function *)
fun make_rec_intr T rec_set ((rec_intr_ts, l), (cname, cargs)) =
let
fun mk_prem ((dt, U), (j, k, prems, t1s, t2s)) =
let val free1 = mk_Free "x" U j
in (case (strip_dtyp dt, strip_type U) of
((_, DtRec m), (Us, _)) =>
let
val free2 = mk_Free "y" (Us ---> List.nth (rec_result_Ts, m)) k;
val i = length Us
in (j + 1, k + 1, HOLogic.mk_Trueprop (HOLogic.list_all
(map (pair "x") Us, List.nth (rec_sets', m) $
app_bnds free1 i $ app_bnds free2 i)) :: prems,
free1::t1s, free2::t2s)
end
| _ => (j + 1, k, prems, free1::t1s, t2s))
end;
val Ts = map (typ_of_dtyp descr' sorts) cargs;
val (_, _, prems, t1s, t2s) = List.foldr mk_prem (1, 1, [], [], []) (cargs ~~ Ts)
in (rec_intr_ts @ [Logic.list_implies (prems, HOLogic.mk_Trueprop
(rec_set $ list_comb (Const (cname, Ts ---> T), t1s) $
list_comb (List.nth (rec_fns, l), t1s @ t2s)))], l + 1)
end;
val (rec_intr_ts, _) = Library.foldl (fn (x, ((d, T), set_name)) =>
Library.foldl (make_rec_intr T set_name) (x, #3 (snd d)))
(([], 0), descr' ~~ recTs ~~ rec_sets');
val ({intrs = rec_intrs, elims = rec_elims, ...}, thy1) =
InductivePackage.add_inductive_global (serial_string ())
{quiet_mode = ! quiet_mode, verbose = false, kind = Thm.internalK,
alt_name = Binding.name big_rec_name', coind = false, no_elim = false, no_ind = true,
skip_mono = true, fork_mono = false}
(map (fn (s, T) => ((Binding.name s, T), NoSyn)) (rec_set_names' ~~ rec_set_Ts))
(map dest_Free rec_fns)
(map (fn x => (Attrib.empty_binding, x)) rec_intr_ts) [] thy0;
(* prove uniqueness and termination of primrec combinators *)
val _ = message "Proving termination and uniqueness of primrec functions ...";
fun mk_unique_tac ((tac, intrs), ((((i, (tname, _, constrs)), elim), T), T')) =
let
val distinct_tac =
(if i < length newTs then
full_simp_tac (HOL_ss addsimps (List.nth (dist_rewrites, i))) 1
else full_simp_tac dist_ss 1);
val inject = map (fn r => r RS iffD1)
(if i < length newTs then List.nth (constr_inject, i)
else #inject (the (Symtab.lookup dt_info tname)));
fun mk_unique_constr_tac n ((tac, intr::intrs, j), (cname, cargs)) =
let
val k = length (List.filter is_rec_type cargs)
in (EVERY [DETERM tac,
REPEAT (etac ex1E 1), rtac ex1I 1,
DEPTH_SOLVE_1 (ares_tac [intr] 1),
REPEAT_DETERM_N k (etac thin_rl 1 THEN rotate_tac 1 1),
etac elim 1,
REPEAT_DETERM_N j distinct_tac,
TRY (dresolve_tac inject 1),
REPEAT (etac conjE 1), hyp_subst_tac 1,
REPEAT (EVERY [etac allE 1, dtac mp 1, atac 1]),
TRY (hyp_subst_tac 1),
rtac refl 1,
REPEAT_DETERM_N (n - j - 1) distinct_tac],
intrs, j + 1)
end;
val (tac', intrs', _) = Library.foldl (mk_unique_constr_tac (length constrs))
((tac, intrs, 0), constrs);
in (tac', intrs') end;
val rec_unique_thms =
let
val rec_unique_ts = map (fn (((set_t, T1), T2), i) =>
Const ("Ex1", (T2 --> HOLogic.boolT) --> HOLogic.boolT) $
absfree ("y", T2, set_t $ mk_Free "x" T1 i $ Free ("y", T2)))
(rec_sets ~~ recTs ~~ rec_result_Ts ~~ (1 upto length recTs));
val cert = cterm_of thy1
val insts = map (fn ((i, T), t) => absfree ("x" ^ (string_of_int i), T, t))
((1 upto length recTs) ~~ recTs ~~ rec_unique_ts);
val induct' = cterm_instantiate ((map cert induct_Ps) ~~
(map cert insts)) induct;
val (tac, _) = Library.foldl mk_unique_tac
(((rtac induct' THEN_ALL_NEW ObjectLogic.atomize_prems_tac) 1
THEN rewrite_goals_tac [mk_meta_eq choice_eq], rec_intrs),
descr' ~~ rec_elims ~~ recTs ~~ rec_result_Ts);
in split_conj_thm (SkipProof.prove_global thy1 [] []
(HOLogic.mk_Trueprop (mk_conj rec_unique_ts)) (K tac))
end;
val rec_total_thms = map (fn r => r RS theI') rec_unique_thms;
(* define primrec combinators *)
val big_reccomb_name = (space_implode "_" new_type_names) ^ "_rec";
val reccomb_names = map (Sign.full_bname thy1)
(if length descr' = 1 then [big_reccomb_name] else
(map ((curry (op ^) (big_reccomb_name ^ "_")) o string_of_int)
(1 upto (length descr'))));
val reccombs = map (fn ((name, T), T') => list_comb
(Const (name, reccomb_fn_Ts @ [T] ---> T'), rec_fns))
(reccomb_names ~~ recTs ~~ rec_result_Ts);
val (reccomb_defs, thy2) =
thy1
|> Sign.add_consts_i (map (fn ((name, T), T') =>
(Binding.name (Long_Name.base_name name), reccomb_fn_Ts @ [T] ---> T', NoSyn))
(reccomb_names ~~ recTs ~~ rec_result_Ts))
|> (PureThy.add_defs false o map Thm.no_attributes) (map (fn ((((name, comb), set), T), T') =>
(Binding.name (Long_Name.base_name name ^ "_def"), Logic.mk_equals (comb, absfree ("x", T,
Const ("The", (T' --> HOLogic.boolT) --> T') $ absfree ("y", T',
set $ Free ("x", T) $ Free ("y", T'))))))
(reccomb_names ~~ reccombs ~~ rec_sets ~~ recTs ~~ rec_result_Ts))
||> parent_path flat_names
||> Theory.checkpoint;
(* prove characteristic equations for primrec combinators *)
val _ = message "Proving characteristic theorems for primrec combinators ..."
val rec_thms = map (fn t => SkipProof.prove_global thy2 [] [] t
(fn _ => EVERY
[rewrite_goals_tac reccomb_defs,
rtac the1_equality 1,
resolve_tac rec_unique_thms 1,
resolve_tac rec_intrs 1,
REPEAT (rtac allI 1 ORELSE resolve_tac rec_total_thms 1)]))
(DatatypeProp.make_primrecs new_type_names descr sorts thy2)
in
thy2
|> Sign.add_path (space_implode "_" new_type_names)
|> PureThy.add_thmss [((Binding.name "recs", rec_thms),
[Nitpick_Const_Simp_Thms.add])]
||> Sign.parent_path
||> Theory.checkpoint
|-> (fn thms => pair (reccomb_names, Library.flat thms))
end;
(***************************** case combinators *******************************)
fun prove_case_thms flat_names new_type_names descr sorts reccomb_names primrec_thms thy =
let
val _ = message "Proving characteristic theorems for case combinators ...";
val thy1 = add_path flat_names (space_implode "_" new_type_names) thy;
val descr' = List.concat descr;
val recTs = get_rec_types descr' sorts;
val used = List.foldr OldTerm.add_typ_tfree_names [] recTs;
val newTs = Library.take (length (hd descr), recTs);
val T' = TFree (Name.variant used "'t", HOLogic.typeS);
fun mk_dummyT dt = binder_types (typ_of_dtyp descr' sorts dt) ---> T';
val case_dummy_fns = map (fn (_, (_, _, constrs)) => map (fn (_, cargs) =>
let
val Ts = map (typ_of_dtyp descr' sorts) cargs;
val Ts' = map mk_dummyT (List.filter is_rec_type cargs)
in Const (@{const_name undefined}, Ts @ Ts' ---> T')
end) constrs) descr';
val case_names = map (fn s => Sign.full_bname thy1 (s ^ "_case")) new_type_names;
(* define case combinators via primrec combinators *)
val (case_defs, thy2) = Library.foldl (fn ((defs, thy),
((((i, (_, _, constrs)), T), name), recname)) =>
let
val (fns1, fns2) = ListPair.unzip (map (fn ((_, cargs), j) =>
let
val Ts = map (typ_of_dtyp descr' sorts) cargs;
val Ts' = Ts @ map mk_dummyT (List.filter is_rec_type cargs);
val frees' = map (uncurry (mk_Free "x")) (Ts' ~~ (1 upto length Ts'));
val frees = Library.take (length cargs, frees');
val free = mk_Free "f" (Ts ---> T') j
in
(free, list_abs_free (map dest_Free frees',
list_comb (free, frees)))
end) (constrs ~~ (1 upto length constrs)));
val caseT = (map (snd o dest_Free) fns1) @ [T] ---> T';
val fns = (List.concat (Library.take (i, case_dummy_fns))) @
fns2 @ (List.concat (Library.drop (i + 1, case_dummy_fns)));
val reccomb = Const (recname, (map fastype_of fns) @ [T] ---> T');
val decl = ((Binding.name (Long_Name.base_name name), caseT), NoSyn);
val def = (Binding.name (Long_Name.base_name name ^ "_def"),
Logic.mk_equals (list_comb (Const (name, caseT), fns1),
list_comb (reccomb, (List.concat (Library.take (i, case_dummy_fns))) @
fns2 @ (List.concat (Library.drop (i + 1, case_dummy_fns))) )));
val ([def_thm], thy') =
thy
|> Sign.declare_const [] decl |> snd
|> (PureThy.add_defs false o map Thm.no_attributes) [def];
in (defs @ [def_thm], thy')
end) (([], thy1), (hd descr) ~~ newTs ~~ case_names ~~
(Library.take (length newTs, reccomb_names)))
||> Theory.checkpoint;
val case_thms = map (map (fn t => SkipProof.prove_global thy2 [] [] t
(fn _ => EVERY [rewrite_goals_tac (case_defs @ map mk_meta_eq primrec_thms), rtac refl 1])))
(DatatypeProp.make_cases new_type_names descr sorts thy2)
in
thy2
|> Context.the_theory o fold (fold Nitpick_Const_Simp_Thms.add_thm) case_thms
o Context.Theory
|> parent_path flat_names
|> store_thmss "cases" new_type_names case_thms
|-> (fn thmss => pair (thmss, case_names))
end;
(******************************* case splitting *******************************)
fun prove_split_thms new_type_names descr sorts constr_inject dist_rewrites
casedist_thms case_thms thy =
let
val _ = message "Proving equations for case splitting ...";
val descr' = List.concat descr;
val recTs = get_rec_types descr' sorts;
val newTs = Library.take (length (hd descr), recTs);
fun prove_split_thms ((((((t1, t2), inject), dist_rewrites'),
exhaustion), case_thms'), T) =
let
val cert = cterm_of thy;
val _ $ (_ $ lhs $ _) = hd (Logic.strip_assums_hyp (hd (prems_of exhaustion)));
val exhaustion' = cterm_instantiate
[(cert lhs, cert (Free ("x", T)))] exhaustion;
val tacf = K (EVERY [rtac exhaustion' 1, ALLGOALS (asm_simp_tac
(HOL_ss addsimps (dist_rewrites' @ inject @ case_thms')))])
in
(SkipProof.prove_global thy [] [] t1 tacf,
SkipProof.prove_global thy [] [] t2 tacf)
end;
val split_thm_pairs = map prove_split_thms
((DatatypeProp.make_splits new_type_names descr sorts thy) ~~ constr_inject ~~
dist_rewrites ~~ casedist_thms ~~ case_thms ~~ newTs);
val (split_thms, split_asm_thms) = ListPair.unzip split_thm_pairs
in
thy
|> store_thms "split" new_type_names split_thms
||>> store_thms "split_asm" new_type_names split_asm_thms
|-> (fn (thms1, thms2) => pair (thms1 ~~ thms2))
end;
fun prove_weak_case_congs new_type_names descr sorts thy =
let
fun prove_weak_case_cong t =
SkipProof.prove_global thy [] (Logic.strip_imp_prems t) (Logic.strip_imp_concl t)
(fn {prems, ...} => EVERY [rtac ((hd prems) RS arg_cong) 1])
val weak_case_congs = map prove_weak_case_cong (DatatypeProp.make_weak_case_congs
new_type_names descr sorts thy)
in thy |> store_thms "weak_case_cong" new_type_names weak_case_congs end;
(************************* additional theorems for TFL ************************)
fun prove_nchotomys new_type_names descr sorts casedist_thms thy =
let
val _ = message "Proving additional theorems for TFL ...";
fun prove_nchotomy (t, exhaustion) =
let
(* For goal i, select the correct disjunct to attack, then prove it *)
fun tac i 0 = EVERY [TRY (rtac disjI1 i),
hyp_subst_tac i, REPEAT (rtac exI i), rtac refl i]
| tac i n = rtac disjI2 i THEN tac i (n - 1)
in
SkipProof.prove_global thy [] [] t (fn _ =>
EVERY [rtac allI 1,
exh_tac (K exhaustion) 1,
ALLGOALS (fn i => tac i (i-1))])
end;
val nchotomys =
map prove_nchotomy (DatatypeProp.make_nchotomys descr sorts ~~ casedist_thms)
in thy |> store_thms "nchotomy" new_type_names nchotomys end;
fun prove_case_congs new_type_names descr sorts nchotomys case_thms thy =
let
fun prove_case_cong ((t, nchotomy), case_rewrites) =
let
val (Const ("==>", _) $ tm $ _) = t;
val (Const ("Trueprop", _) $ (Const ("op =", _) $ _ $ Ma)) = tm;
val cert = cterm_of thy;
val nchotomy' = nchotomy RS spec;
val [v] = Term.add_vars (concl_of nchotomy') [];
val nchotomy'' = cterm_instantiate [(cert (Var v), cert Ma)] nchotomy'
in
SkipProof.prove_global thy [] (Logic.strip_imp_prems t) (Logic.strip_imp_concl t)
(fn {prems, ...} =>
let val simplify = asm_simp_tac (HOL_ss addsimps (prems @ case_rewrites))
in EVERY [simp_tac (HOL_ss addsimps [hd prems]) 1,
cut_facts_tac [nchotomy''] 1,
REPEAT (etac disjE 1 THEN REPEAT (etac exE 1) THEN simplify 1),
REPEAT (etac exE 1) THEN simplify 1 (* Get last disjunct *)]
end)
end;
val case_congs = map prove_case_cong (DatatypeProp.make_case_congs
new_type_names descr sorts thy ~~ nchotomys ~~ case_thms)
in thy |> store_thms "case_cong" new_type_names case_congs end;
end;