From: Claudio Sacerdoti Coen <claudio.sacerdoticoen@unibo.it>
Date: Sat, 25 Apr 2009 20:28:07 +0000 (+0000)
Subject: Type for list_index improved.
X-Git-Tag: make_still_working~4052
X-Git-Url: http://matita.cs.unibo.it/gitweb/?a=commitdiff_plain;h=9bb529b1b6620f1cbb249104ef9303b130acb315;p=helm.git

Type for list_index improved.
---

diff --git a/helm/software/components/extlib/hExtlib.ml b/helm/software/components/extlib/hExtlib.ml
index 523913cbf..3ef795e9f 100644
--- a/helm/software/components/extlib/hExtlib.ml
+++ b/helm/software/components/extlib/hExtlib.ml
@@ -148,6 +148,16 @@ let list_mapi f l =
      aux 0 l
 ;;
 
+let list_index p =
+ let rec aux n =
+  function
+     [] -> None
+   | he::_ when p he -> Some (n,he)
+   | _::tl -> aux (n + 1) tl
+ in
+  aux 0
+;;
+
 let rec list_iter_default2 f l1 def l2 = 
   match l1,l2 with
     | [], _ -> ()