src/ZF/Tools/typechk.ML
author wenzelm
Sat Jan 21 23:02:29 2006 +0100 (2006-01-21)
changeset 18736 541d04c79e12
parent 18708 4b3dadb4fe33
child 20193 46f5ef758422
permissions -rw-r--r--
simplified type attribute;
removed obsolete tcset operations -- clean data/attribute/method setup;
     1 (*  Title:      ZF/Tools/typechk.ML
     2     ID:         $Id$
     3     Author:     Lawrence C Paulson, Cambridge University Computer Laboratory
     4     Copyright   1999  University of Cambridge
     5 
     6 Automated type checking (cf. CTT).
     7 *)
     8 
     9 signature TYPE_CHECK =
    10 sig
    11   val print_tcset: Context.generic -> unit
    12   val TC_add: attribute
    13   val TC_del: attribute
    14   val typecheck_tac: Proof.context -> tactic
    15   val type_solver_tac: Proof.context -> thm list -> int -> tactic
    16   val type_solver: solver
    17   val setup: theory -> theory
    18 end;
    19 
    20 structure TypeCheck: TYPE_CHECK =
    21 struct
    22 
    23 (* datatype tcset *)
    24 
    25 datatype tcset = TC of
    26  {rules: thm list,     (*the type-checking rules*)
    27   net: thm Net.net};   (*discrimination net of the same rules*)
    28 
    29 fun add_rule th (tcs as TC {rules, net}) =
    30   if member Drule.eq_thm_prop rules th then
    31     (warning ("Ignoring duplicate type-checking rule\n" ^ Display.string_of_thm th); tcs)
    32   else
    33     TC {rules = th :: rules,
    34         net = Net.insert_term (K false) (Thm.concl_of th, th) net};
    35 
    36 fun del_rule th (tcs as TC {rules, net}) =
    37   if member Drule.eq_thm_prop rules th then
    38     TC {net = Net.delete_term Drule.eq_thm_prop (Thm.concl_of th, th) net,
    39         rules = remove Drule.eq_thm_prop th rules}
    40   else (warning ("No such type-checking rule\n" ^ Display.string_of_thm th); tcs);
    41 
    42 
    43 (* generic data *)
    44 
    45 structure Data = GenericDataFun
    46 (
    47   val name = "ZF/type-checking";
    48   type T = tcset
    49   val empty = TC {rules = [], net = Net.empty};
    50   val extend = I;
    51 
    52   fun merge _ (TC {rules, net}, TC {rules = rules', net = net'}) =
    53     TC {rules = gen_union Drule.eq_thm_prop (rules, rules'),
    54         net = Net.merge Drule.eq_thm_prop (net, net')};
    55 
    56   fun print context (TC {rules, ...}) =
    57     Pretty.writeln (Pretty.big_list "type-checking rules:"
    58       (map (ProofContext.pretty_thm (Context.proof_of context)) rules));
    59 );
    60 
    61 val print_tcset = Data.print;
    62 
    63 val TC_add = Thm.declaration_attribute (Data.map o add_rule);
    64 val TC_del = Thm.declaration_attribute (Data.map o del_rule);
    65 
    66 val tcset_of = Data.get o Context.Proof;
    67 
    68 
    69 (* tactics *)
    70 
    71 (*resolution using a net rather than rules*)
    72 fun net_res_tac maxr net =
    73   SUBGOAL
    74     (fn (prem,i) =>
    75       let val rls = Net.unify_term net (Logic.strip_assums_concl prem)
    76       in
    77          if length rls <= maxr then resolve_tac rls i else no_tac
    78       end);
    79 
    80 fun is_rigid_elem (Const("Trueprop",_) $ (Const("op :",_) $ a $ _)) =
    81       not (is_Var (head_of a))
    82   | is_rigid_elem _ = false;
    83 
    84 (*Try solving a:A by assumption provided a is rigid!*)
    85 val test_assume_tac = SUBGOAL(fn (prem,i) =>
    86     if is_rigid_elem (Logic.strip_assums_concl prem)
    87     then  assume_tac i  else  eq_assume_tac i);
    88 
    89 (*Type checking solves a:?A (a rigid, ?A maybe flexible).
    90   match_tac is too strict; would refuse to instantiate ?A*)
    91 fun typecheck_step_tac (TC{net,...}) =
    92     FIRSTGOAL (test_assume_tac ORELSE' net_res_tac 3 net);
    93 
    94 fun typecheck_tac ctxt = REPEAT (typecheck_step_tac (tcset_of ctxt));
    95 
    96 (*Compiles a term-net for speed*)
    97 val basic_res_tac = net_resolve_tac [TrueI,refl,reflexive_thm,iff_refl,
    98                                      ballI,allI,conjI,impI];
    99 
   100 (*Instantiates variables in typing conditions.
   101   drawback: does not simplify conjunctions*)
   102 fun type_solver_tac ctxt hyps = SELECT_GOAL
   103     (DEPTH_SOLVE (etac FalseE 1
   104                   ORELSE basic_res_tac 1
   105                   ORELSE (ares_tac hyps 1
   106                           APPEND typecheck_step_tac (tcset_of ctxt))));
   107 
   108 val type_solver = Simplifier.mk_solver' "ZF typecheck" (fn ss =>
   109   type_solver_tac (Simplifier.the_context ss) (Simplifier.prems_of_ss ss));
   110 
   111 
   112 (* concrete syntax *)
   113 
   114 val TC_att = Attrib.add_del_args TC_add TC_del;
   115 
   116 val typecheck_meth =
   117   Method.only_sectioned_args
   118     [Args.add -- Args.colon >> K (I, TC_add),
   119      Args.del -- Args.colon >> K (I, TC_del)]
   120   (fn ctxt => Method.SIMPLE_METHOD (CHANGED (typecheck_tac ctxt)));
   121 
   122 val _ = OuterSyntax.add_parsers
   123   [OuterSyntax.improper_command "print_tcset" "print context of ZF typecheck" OuterKeyword.diag
   124     (Scan.succeed (Toplevel.no_timing o Toplevel.unknown_context o
   125       Toplevel.keep (print_tcset o Toplevel.context_of)))];
   126 
   127 
   128 (* theory setup *)
   129 
   130 val setup =
   131   Data.init #>
   132   Attrib.add_attributes [("TC", TC_att, "declaration of type-checking rule")] #>
   133   Method.add_methods [("typecheck", typecheck_meth, "ZF type-checking")] #>
   134   (fn thy => (change_simpset_of thy (fn ss => ss setSolver type_solver); thy));
   135 
   136 end;