# HG changeset patch
# User paulson
# Date 864306549 -7200
# Node ID c9c99aa082fb6b44c16f5f10603299c56ab3f25b
# Parent  4c73b6508f535603e62969bb73bd2799e9288a1e
Deleted obsolete proofs.  But option_case_tac will be obsolete too

diff -r 4c73b6508f53 -r c9c99aa082fb src/HOL/Option.ML
--- a/src/HOL/Option.ML	Thu May 22 15:08:14 1997 +0200
+++ b/src/HOL/Option.ML	Thu May 22 15:09:09 1997 +0200
@@ -8,20 +8,23 @@
 
 open Option;
 
-val [prem] = goal Option.thy "P(opt) ==> P(None) | (? x. P(Some(x)))";
- br (prem RS rev_mp) 1;
- by (option.induct_tac "opt" 1);
- by (ALLGOALS Blast_tac);
-bind_thm("optionE", standard(result() RS disjE));
-(*
-goal Option.thy "opt=None | (? x.opt=Some(x))"; 
-by (option.induct_tac "opt" 1);
-by (Simp_tac 1);
-by (rtac disjI2 1);
-by (rtac exI 1);
-by (Asm_full_simp_tac 1);
-qed"option_cases";
-*)
+val opt_exhaustion = #nchotomy (the (datatype_info Option.thy "option")) 
+                     RS spec;
+
+(*---------------------------------------------------------------------------
+ * Do a case analysis on something of type 'a option. 
+ *---------------------------------------------------------------------------*)
+
+fun option_case_tac t =
+    (cut_inst_tac [("x",t)] opt_exhaustion 
+      THEN' etac disjE 
+      THEN' rotate_tac ~1 
+      THEN' Asm_full_simp_tac 
+      THEN' etac exE
+      THEN' rotate_tac ~1 
+      THEN' Asm_full_simp_tac);
+
+
 goal Option.thy "P(case opt of None => a | Some(x) => b(x)) = \
 \                ((opt = None --> P a) & (!x. opt = Some x --> P(b(x))))";
 by (option.induct_tac "opt" 1);