X-Git-Url: http://matita.cs.unibo.it/gitweb/?a=blobdiff_plain;f=components%2Ftactics%2Ftacticals.ml;h=f647ebccaa9d199181761b2233c59f00ace13f1d;hb=cf9784a6b94fa9045810d8559509b54dc9e65a4a;hp=d5ec8acfb8be6c9edee7f353ba9f5368f8314511;hpb=f38af523cd051d4c1d0dceeb59ce2fbbfc87367d;p=helm.git

diff --git a/components/tactics/tacticals.ml b/components/tactics/tacticals.ml
index d5ec8acfb..f647ebcca 100644
--- a/components/tactics/tacticals.ml
+++ b/components/tactics/tacticals.ml
@@ -201,6 +201,23 @@ let if_ ~start ~continuation ~fail =
    in
    PET.mk_tactic if_
 
+let ifs ~start ~continuations ~fail =
+   let ifs status =
+      let xoutput = 
+         try
+	    let result = PET.apply_tactic start status in
+	    info (lazy ("Tacticals.ifs: succedeed!!!"));
+	    Some result 
+	 with PET.Fail _ -> None
+      in
+      let tactic = match xoutput with
+         | Some res -> thens ~start:(const_tac res) ~continuations
+	 | None     -> fail
+      in 
+      PET.apply_tactic tactic status
+   in
+   PET.mk_tactic ifs
+
 let first ~tactics =
   let rec first ~(tactics: tactic list) status =
     info (lazy "in Tacticals.first");