src/Tools/misc_legacy.ML

+(*  Title:      Tools/misc_legacy.ML
+
+Misc legacy stuff -- to be phased out eventually.
+*)
+
+signature MISC_LEGACY =
+sig
+  val mk_defpair: term * term -> string * term
+  val get_def: theory -> xstring -> thm
+  val simple_read_term: theory -> typ -> string -> term
+  val METAHYPS: (thm list -> tactic) -> int -> tactic
+end;
+
+structure Misc_Legacy: MISC_LEGACY =
+struct
+
+fun mk_defpair (lhs, rhs) =
+  (case Term.head_of lhs of
+    Const (name, _) =>
+      (Long_Name.base_name name ^ "_def", Logic.mk_equals (lhs, rhs))
+  | _ => raise TERM ("Malformed definition: head of lhs not a constant", [lhs, rhs]));
+
+
+fun get_def thy = Thm.axiom thy o Name_Space.intern (Theory.axiom_space thy) o Thm.def_name;
+
+
+fun simple_read_term thy T s =
+  let
+    val ctxt = ProofContext.init_global thy
+      |> ProofContext.allow_dummies
+      |> ProofContext.set_mode ProofContext.mode_schematic;
+    val parse = if T = propT then Syntax.parse_prop else Syntax.parse_term;
+  in parse ctxt s |> Type_Infer.constrain T |> Syntax.check_term ctxt end;
+
+
+(**** METAHYPS -- tactical for using hypotheses as meta-level assumptions
+       METAHYPS (fn prems => tac prems) i
+
+converts subgoal i, of the form !!x1...xm. [| A1;...;An] ==> A into a new
+proof state A==>A, supplying A1,...,An as meta-level assumptions (in
+"prems").  The parameters x1,...,xm become free variables.  If the
+resulting proof state is [| B1;...;Bk] ==> C (possibly assuming A1,...,An)
+then it is lifted back into the original context, yielding k subgoals.
+
+Replaces unknowns in the context by Frees having the prefix METAHYP_
+New unknowns in [| B1;...;Bk] ==> C are lifted over x1,...,xm.
+DOES NOT HANDLE TYPE UNKNOWNS.
+
+
+NOTE: This version does not observe the proof context, and thus cannot
+work reliably.  See also Subgoal.SUBPROOF and Subgoal.FOCUS for
+properly localized variants of the same idea.
+****)
+
+local
+
+(*Strips assumptions in goal yielding  ( [x1,...,xm], [H1,...,Hn], B )
+    H1,...,Hn are the hypotheses;  x1...xm are variants of the parameters.
+  Main difference from strip_assums concerns parameters:
+    it replaces the bound variables by free variables.  *)
+fun strip_context_aux (params, Hs, Const ("==>", _) $ H $ B) =
+      strip_context_aux (params, H :: Hs, B)
+  | strip_context_aux (params, Hs, Const ("all",_) $ Abs (a, T, t)) =
+      let val (b, u) = Syntax.variant_abs (a, T, t)
+      in strip_context_aux ((b, T) :: params, Hs, u) end
+  | strip_context_aux (params, Hs, B) = (rev params, rev Hs, B);
+
+fun strip_context A = strip_context_aux ([], [], A);
+
+(*Left-to-right replacements: ctpairs = [...,(vi,ti),...].
+  Instantiates distinct free variables by terms of same type.*)
+fun free_instantiate ctpairs =
+  forall_elim_list (map snd ctpairs) o forall_intr_list (map fst ctpairs);
+
+fun free_of s ((a, i), T) =
+  Free (s ^ (case i of 0 => a | _ => a ^ "_" ^ string_of_int i), T)
+
+fun mk_inst v = (Var v, free_of "METAHYP1_" v)
+
+fun metahyps_split_prem prem =
+  let (*find all vars in the hyps -- should find tvars also!*)
+      val hyps_vars = fold Term.add_vars (Logic.strip_assums_hyp prem) []
+      val insts = map mk_inst hyps_vars
+      (*replace the hyps_vars by Frees*)
+      val prem' = subst_atomic insts prem
+      val (params,hyps,concl) = strip_context prem'
+  in (insts,params,hyps,concl)  end;
+
+fun metahyps_aux_tac tacf (prem,gno) state =
+  let val (insts,params,hyps,concl) = metahyps_split_prem prem
+      val maxidx = Thm.maxidx_of state
+      val cterm = Thm.cterm_of (Thm.theory_of_thm state)
+      val chyps = map cterm hyps
+      val hypths = map Thm.assume chyps
+      val subprems = map (Thm.forall_elim_vars 0) hypths
+      val fparams = map Free params
+      val cparams = map cterm fparams
+      fun swap_ctpair (t,u) = (cterm u, cterm t)
+      (*Subgoal variables: make Free; lift type over params*)
+      fun mk_subgoal_inst concl_vars (v, T) =
+          if member (op =) concl_vars (v, T)
+          then ((v, T), true, free_of "METAHYP2_" (v, T))
+          else ((v, T), false, free_of "METAHYP2_" (v, map #2 params ---> T))
+      (*Instantiate subgoal vars by Free applied to params*)
+      fun mk_ctpair (v, in_concl, u) =
+          if in_concl then (cterm (Var v), cterm u)
+          else (cterm (Var v), cterm (list_comb (u, fparams)))
+      (*Restore Vars with higher type and index*)
+      fun mk_subgoal_swap_ctpair (((a, i), T), in_concl, u as Free (_, U)) =
+          if in_concl then (cterm u, cterm (Var ((a, i), T)))
+          else (cterm u, cterm (Var ((a, i + maxidx), U)))
+      (*Embed B in the original context of params and hyps*)
+      fun embed B = list_all_free (params, Logic.list_implies (hyps, B))
+      (*Strip the context using elimination rules*)
+      fun elim Bhyp = implies_elim_list (forall_elim_list cparams Bhyp) hypths
+      (*A form of lifting that discharges assumptions.*)
+      fun relift st =
+        let val prop = Thm.prop_of st
+            val subgoal_vars = (*Vars introduced in the subgoals*)
+              fold Term.add_vars (Logic.strip_imp_prems prop) []
+            and concl_vars = Term.add_vars (Logic.strip_imp_concl prop) []
+            val subgoal_insts = map (mk_subgoal_inst concl_vars) subgoal_vars
+            val st' = Thm.instantiate ([], map mk_ctpair subgoal_insts) st
+            val emBs = map (cterm o embed) (prems_of st')
+            val Cth  = implies_elim_list st' (map (elim o Thm.assume) emBs)
+        in  (*restore the unknowns to the hypotheses*)
+            free_instantiate (map swap_ctpair insts @
+                              map mk_subgoal_swap_ctpair subgoal_insts)
+                (*discharge assumptions from state in same order*)
+                (implies_intr_list emBs
+                  (forall_intr_list cparams (implies_intr_list chyps Cth)))
+        end
+      (*function to replace the current subgoal*)
+      fun next st = Thm.bicompose false (false, relift st, nprems_of st) gno state
+  in Seq.maps next (tacf subprems (Thm.trivial (cterm concl))) end;
+
+fun print_vars_terms n thm =
+  let
+    val thy = theory_of_thm thm
+    fun typed s ty =
+      "  " ^ s ^ " has type: " ^ Syntax.string_of_typ_global thy ty;
+    fun find_vars (Const (c, ty)) =
+          if null (Term.add_tvarsT ty []) then I
+          else insert (op =) (typed c ty)
+      | find_vars (Var (xi, ty)) =
+          insert (op =) (typed (Term.string_of_vname xi) ty)
+      | find_vars (Free _) = I
+      | find_vars (Bound _) = I
+      | find_vars (Abs (_, _, t)) = find_vars t
+      | find_vars (t1 $ t2) = find_vars t1 #> find_vars t2;
+    val prem = Logic.nth_prem (n, Thm.prop_of thm)
+    val tms = find_vars prem []
+  in warning (cat_lines ("Found schematic vars in assumptions:" :: tms)) end;
+
+in
+
+fun METAHYPS tacf n thm = SUBGOAL (metahyps_aux_tac tacf) n thm
+  handle THM("assume: variables",_,_) => (print_vars_terms n thm; Seq.empty)
+
+end;
+
+end;
+