src/Provers/ind.ML
author skalberg
Thu Mar 03 12:43:01 2005 +0100 (2005-03-03)
changeset 15570 8d8c70b41bab
parent 15462 b4208fbf9439
child 19299 5f0610aafc48
permissions -rw-r--r--
Move towards standard functions.
     1 (*  Title: 	Provers/ind
     2     ID:         $Id$
     3     Author: 	Tobias Nipkow
     4     Copyright   1991  University of Cambridge
     5 
     6 Generic induction package -- for use with simplifier
     7 *)
     8 
     9 signature IND_DATA =
    10   sig
    11   val spec: thm (* All(?P) ==> ?P(?a) *)
    12   end;
    13 
    14 
    15 signature IND =
    16   sig
    17   val all_frees_tac: string -> int -> tactic
    18   val ALL_IND_TAC: thm -> (int -> tactic) -> (int -> tactic)
    19   val IND_TAC: thm -> (int -> tactic) -> string -> (int -> tactic)
    20   end;
    21 
    22 
    23 functor InductionFun(Ind_Data: IND_DATA):IND =
    24 struct
    25 local open Ind_Data in
    26 
    27 val _$(_$Var(a_ixname,aT)) = concl_of spec;
    28 
    29 fun add_term_frees tsig =
    30 let fun add(tm, vars) = case tm of
    31 	Free(v,T) => if Type.typ_instance tsig (T,aT) then v ins vars
    32 		     else vars
    33       | Abs (_,_,body) => add(body,vars)
    34       | rator$rand => add(rator, add(rand, vars))
    35       | _ => vars
    36 in add end;
    37 
    38 
    39 fun qnt_tac i = fn (tac,var) => tac THEN Tactic.res_inst_tac' [(a_ixname,var)] spec i;
    40 
    41 (*Generalizes over all free variables, with the named var outermost.*)
    42 fun all_frees_tac (var:string) i thm = 
    43     let val tsig = Sign.tsig_of (Thm.sign_of_thm thm);
    44         val frees = add_term_frees tsig (List.nth(prems_of thm,i-1),[var]);
    45         val frees' = sort (rev_order o string_ord) (frees \ var) @ [var]
    46     in Library.foldl (qnt_tac i) (all_tac,frees') thm end;
    47 
    48 fun REPEAT_SIMP_TAC simp_tac n i =
    49 let fun repeat thm = 
    50         (COND (has_fewer_prems n) all_tac
    51 	 let val k = nprems_of thm
    52 	 in simp_tac i THEN COND (has_fewer_prems k) repeat all_tac end)
    53 	thm
    54 in repeat end;
    55 
    56 fun ALL_IND_TAC sch simp_tac i thm = 
    57 	(resolve_tac [sch] i THEN
    58 	 REPEAT_SIMP_TAC simp_tac (nprems_of thm) i) thm;
    59 
    60 fun IND_TAC sch simp_tac var =
    61 	all_frees_tac var THEN' ALL_IND_TAC sch simp_tac;
    62 
    63 
    64 end
    65 end;