(* Title: Pure/Isar/rule_insts.ML
ID: $Id$
Author: Makarius
Rule instantiations -- operations within a rule/subgoal context.
*)
signature RULE_INSTS =
sig
val bires_inst_tac: bool -> Proof.context -> (indexname * string) list ->
thm -> int -> tactic
end;
structure RuleInsts: RULE_INSTS =
struct
(** reading instantiations **)
local
fun is_tvar (x, _) = String.isPrefix "'" x;
fun error_var msg xi = error (msg ^ Syntax.string_of_vname xi);
fun the_sort tvars xi = the (AList.lookup (op =) tvars xi)
handle Option.Option => error_var "No such type variable in theorem: " xi;
fun the_type vars xi = the (AList.lookup (op =) vars xi)
handle Option.Option => error_var "No such variable in theorem: " xi;
fun unify_vartypes thy vars (xi, u) (unifier, maxidx) =
let
val T = the_type vars xi;
val U = Term.fastype_of u;
val maxidx' = Term.maxidx_term u (Int.max (#2 xi, maxidx));
in
Sign.typ_unify thy (T, U) (unifier, maxidx')
handle Type.TUNIFY => error_var "Incompatible type for instantiation of " xi
end;
fun instantiate inst =
TermSubst.instantiate ([], map (fn (xi, t) => ((xi, Term.fastype_of t), t)) inst) #>
Envir.beta_norm;
fun make_instT f v =
let
val T = TVar v;
val T' = f T;
in if T = T' then NONE else SOME (T, T') end;
fun make_inst f v =
let
val t = Var v;
val t' = f t;
in if t aconv t' then NONE else SOME (t, t') end;
in
fun read_insts ctxt mixed_insts (tvars, vars) =
let
val thy = ProofContext.theory_of ctxt;
val cert = Thm.cterm_of thy;
val certT = Thm.ctyp_of thy;
val (type_insts, term_insts) = List.partition (is_tvar o fst) mixed_insts;
val internal_insts = term_insts |> map_filter
(fn (xi, Args.Term t) => SOME (xi, t)
| (_, Args.Text _) => NONE
| (xi, _) => error_var "Term argument expected for " xi);
val external_insts = term_insts |> map_filter
(fn (xi, Args.Text s) => SOME (xi, s) | _ => NONE);
(* mixed type instantiations *)
fun readT (xi, arg) =
let
val S = the_sort tvars xi;
val T =
(case arg of
Args.Text s => ProofContext.read_typ ctxt s
| Args.Typ T => T
| _ => error_var "Type argument expected for " xi);
in
if Sign.of_sort thy (T, S) then ((xi, S), T)
else error_var "Incompatible sort for typ instantiation of " xi
end;
val type_insts1 = map readT type_insts;
val instT1 = TermSubst.instantiateT type_insts1;
val vars1 = map (apsnd instT1) vars;
(* internal term instantiations *)
val instT2 = Envir.norm_type
(#1 (fold (unify_vartypes thy vars1) internal_insts (Vartab.empty, 0)));
val vars2 = map (apsnd instT2) vars1;
val internal_insts2 = map (apsnd (map_types instT2)) internal_insts;
val inst2 = instantiate internal_insts2;
(* external term instantiations *)
val (xs, strs) = split_list external_insts;
val Ts = map (the_type vars2) xs;
val (ts, inferred) = (* FIXME polymorphic!? schematic vs. 'for' context!? *)
ProofContext.read_termTs_schematic ctxt (K false) (K NONE) (K NONE) [] (strs ~~ Ts);
val instT3 = Term.typ_subst_TVars inferred;
val vars3 = map (apsnd instT3) vars2;
val internal_insts3 = map (apsnd (map_types instT3)) internal_insts2;
val external_insts3 = xs ~~ ts;
val inst3 = instantiate external_insts3;
(* results *)
val type_insts3 = map (fn ((a, _), T) => (a, instT3 (instT2 T))) type_insts1;
val term_insts3 = internal_insts3 @ external_insts3;
val inst_tvars = map_filter (make_instT (instT3 o instT2 o instT1)) tvars;
val inst_vars = map_filter (make_inst (inst3 o inst2)) vars3;
in
((type_insts3, term_insts3),
(map (pairself certT) inst_tvars, map (pairself cert) inst_vars))
end;
fun read_instantiate ctxt mixed_insts thm =
let
val ctxt' = ctxt |> Variable.declare_thm thm
|> fold (fn a => Variable.declare_internal (Logic.mk_type (TFree (a, [])))) (Drule.add_used thm []); (* FIXME tmp *)
val tvars = Drule.fold_terms Term.add_tvars thm [];
val vars = Drule.fold_terms Term.add_vars thm [];
val ((type_insts, term_insts), insts) = read_insts ctxt' (map snd mixed_insts) (tvars, vars);
val _ = (*assign internalized values*)
mixed_insts |> List.app (fn (arg, (xi, _)) =>
if is_tvar xi then
Args.assign (SOME (Args.Typ (the (AList.lookup (op =) type_insts xi)))) arg
else
Args.assign (SOME (Args.Term (the (AList.lookup (op =) term_insts xi)))) arg);
in
Drule.instantiate insts thm |> RuleCases.save thm
end;
fun read_instantiate' ctxt (args, concl_args) thm =
let
fun zip_vars _ [] = []
| zip_vars (_ :: xs) ((_, NONE) :: rest) = zip_vars xs rest
| zip_vars ((x, _) :: xs) ((arg, SOME t) :: rest) = (arg, (x, t)) :: zip_vars xs rest
| zip_vars [] _ = error "More instantiations than variables in theorem";
val insts =
zip_vars (rev (Term.add_vars (Thm.full_prop_of thm) [])) args @
zip_vars (rev (Term.add_vars (Thm.concl_of thm) [])) concl_args;
in read_instantiate ctxt insts thm end;
end;
(** attributes **)
(* where: named instantiation *)
local
val value =
Args.internal_typ >> Args.Typ ||
Args.internal_term >> Args.Term ||
Args.name >> Args.Text;
val inst = Args.var -- (Args.$$$ "=" |-- Args.ahead -- value)
>> (fn (xi, (a, v)) => (a, (xi, v)));
in
val where_att = Attrib.syntax (Args.and_list (Scan.lift inst) >> (fn args =>
Thm.rule_attribute (fn context => read_instantiate (Context.proof_of context) args)));
end;
(* of: positional instantiation (terms only) *)
local
val value =
Args.internal_term >> Args.Term ||
Args.name >> Args.Text;
val inst = Args.ahead -- Args.maybe value;
val concl = Args.$$$ "concl" -- Args.colon;
val insts =
Scan.repeat (Scan.unless concl inst) --
Scan.optional (concl |-- Scan.repeat inst) [];
in
val of_att = Attrib.syntax (Scan.lift insts >> (fn args =>
Thm.rule_attribute (fn context => read_instantiate' (Context.proof_of context) args)));
end;
(* setup *)
val _ = Context.add_setup (Attrib.add_attributes
[("where", where_att, "named instantiation of theorem"),
("of", of_att, "positional instantiation of theorem")]);
(** methods **)
(* rule_tac etc. -- refer to dynamic goal state!! *) (* FIXME cleanup!! *)
fun bires_inst_tac bires_flag ctxt insts thm =
let
val thy = ProofContext.theory_of ctxt;
(* Separate type and term insts *)
fun has_type_var ((x, _), _) = (case Symbol.explode x of
"'"::cs => true | cs => false);
val Tinsts = List.filter has_type_var insts;
val tinsts = filter_out has_type_var insts;
(* Tactic *)
fun tac i st =
let
(* Preprocess state: extract environment information:
- variables and their types
- type variables and their sorts
- parameters and their types *)
val (types, sorts) = types_sorts st;
(* Process type insts: Tinsts_env *)
fun absent xi = error
("No such variable in theorem: " ^ Syntax.string_of_vname xi);
val (rtypes, rsorts) = types_sorts thm;
fun readT (xi, s) =
let val S = case rsorts xi of SOME S => S | NONE => absent xi;
val T = Sign.read_typ (thy, sorts) s;
val U = TVar (xi, S);
in if Sign.typ_instance thy (T, U) then (U, T)
else error
("Instantiation of " ^ Syntax.string_of_vname xi ^ " fails")
end;
val Tinsts_env = map readT Tinsts;
(* Preprocess rule: extract vars and their types, apply Tinsts *)
fun get_typ xi =
(case rtypes xi of
SOME T => typ_subst_atomic Tinsts_env T
| NONE => absent xi);
val (xis, ss) = Library.split_list tinsts;
val Ts = map get_typ xis;
val (_, _, Bi, _) = dest_state(st,i)
val params = Logic.strip_params Bi
(* params of subgoal i as string typ pairs *)
val params = rev(Term.rename_wrt_term Bi params)
(* as they are printed: bound variables with *)
(* the same name are renamed during printing *)
fun types' (a, ~1) = (case AList.lookup (op =) params a of
NONE => types (a, ~1)
| some => some)
| types' xi = types xi;
fun internal x = is_some (types' (x, ~1));
val used = Drule.add_used thm (Drule.add_used st []);
val (ts, envT) =
ProofContext.read_termTs_schematic ctxt internal types' sorts used (ss ~~ Ts);
val envT' = map (fn (ixn, T) =>
(TVar (ixn, the (rsorts ixn)), T)) envT @ Tinsts_env;
val cenv =
map
(fn (xi, t) =>
pairself (Thm.cterm_of thy) (Var (xi, fastype_of t), t))
(distinct
(fn ((x1, t1), (x2, t2)) => x1 = x2 andalso t1 aconv t2)
(xis ~~ ts));
(* Lift and instantiate rule *)
val {maxidx, ...} = rep_thm st;
val paramTs = map #2 params
and inc = maxidx+1
fun liftvar (Var ((a,j), T)) =
Var((a, j+inc), paramTs ---> Logic.incr_tvar inc T)
| liftvar t = raise TERM("Variable expected", [t]);
fun liftterm t = list_abs_free
(params, Logic.incr_indexes(paramTs,inc) t)
fun liftpair (cv,ct) =
(cterm_fun liftvar cv, cterm_fun liftterm ct)
val lifttvar = pairself (ctyp_of thy o Logic.incr_tvar inc);
val rule = Drule.instantiate
(map lifttvar envT', map liftpair cenv)
(Thm.lift_rule (Thm.cprem_of st i) thm)
in
if i > nprems_of st then no_tac st
else st |>
compose_tac (bires_flag, rule, nprems_of thm) i
end
handle TERM (msg,_) => (warning msg; no_tac st)
| THM (msg,_,_) => (warning msg; no_tac st);
in tac end;
local
fun gen_inst _ tac _ (quant, ([], thms)) =
Method.METHOD (fn facts => quant (Method.insert_tac facts THEN' tac thms))
| gen_inst inst_tac _ ctxt (quant, (insts, [thm])) =
Method.METHOD (fn facts =>
quant (Method.insert_tac facts THEN' inst_tac ctxt insts thm))
| gen_inst _ _ _ _ = error "Cannot have instantiations with multiple rules";
in
val res_inst_meth = gen_inst (bires_inst_tac false) Tactic.resolve_tac;
val eres_inst_meth = gen_inst (bires_inst_tac true) Tactic.eresolve_tac;
val cut_inst_meth =
gen_inst
(fn ctxt => fn insts => bires_inst_tac false ctxt insts o Tactic.make_elim_preserve)
Tactic.cut_rules_tac;
val dres_inst_meth =
gen_inst
(fn ctxt => fn insts => bires_inst_tac true ctxt insts o Tactic.make_elim_preserve)
Tactic.dresolve_tac;
val forw_inst_meth =
gen_inst
(fn ctxt => fn insts => fn rule =>
bires_inst_tac false ctxt insts (Tactic.make_elim_preserve rule) THEN'
assume_tac)
Tactic.forward_tac;
fun subgoal_tac ctxt sprop =
DETERM o bires_inst_tac false ctxt [(("psi", 0), sprop)] cut_rl;
fun subgoals_tac ctxt sprops = EVERY' (map (subgoal_tac ctxt) sprops);
fun thin_tac ctxt s =
bires_inst_tac true ctxt [(("V", 0), s)] thin_rl;
(* method syntax *)
val insts =
Scan.optional
(Args.enum1 "and" (Scan.lift (Args.name -- (Args.$$$ "=" |-- Args.!!! Args.name))) --|
Scan.lift (Args.$$$ "in")) [] -- Attrib.thms;
fun inst_args f src ctxt =
f ctxt (#2 (Method.syntax (Args.goal_spec HEADGOAL -- insts) src ctxt));
val insts_var =
Scan.optional
(Args.enum1 "and" (Scan.lift (Args.var -- (Args.$$$ "=" |-- Args.!!! Args.name))) --|
Scan.lift (Args.$$$ "in")) [] -- Attrib.thms;
fun inst_args_var f src ctxt =
f ctxt (#2 (Method.syntax (Args.goal_spec HEADGOAL -- insts_var) src ctxt));
(* setup *)
val _ = Context.add_setup (Method.add_methods
[("rule_tac", inst_args_var res_inst_meth,
"apply rule (dynamic instantiation)"),
("erule_tac", inst_args_var eres_inst_meth,
"apply rule in elimination manner (dynamic instantiation)"),
("drule_tac", inst_args_var dres_inst_meth,
"apply rule in destruct manner (dynamic instantiation)"),
("frule_tac", inst_args_var forw_inst_meth,
"apply rule in forward manner (dynamic instantiation)"),
("cut_tac", inst_args_var cut_inst_meth,
"cut rule (dynamic instantiation)"),
("subgoal_tac", Method.goal_args_ctxt (Scan.repeat1 Args.name) subgoals_tac,
"insert subgoal (dynamic instantiation)"),
("thin_tac", Method.goal_args_ctxt Args.name thin_tac,
"remove premise (dynamic instantiation)")]);
end;
end;