X-Git-Url: http://matita.cs.unibo.it/gitweb/?a=blobdiff_plain;f=helm%2Fsoftware%2Fcomponents%2Fextlib%2FhExtlib.ml;h=361587b7d33402f4d3989ffde01d72538a88deb6;hb=b3e08a6954c8b6946f42f5c7e0bed7912d5ac87c;hp=fe0f417cdf88521a401a54d0ebbf41ba79ef0b58;hpb=ff5d621723a60609c67152c110b8386f7902c1ff;p=helm.git

diff --git a/helm/software/components/extlib/hExtlib.ml b/helm/software/components/extlib/hExtlib.ml
index fe0f417cd..361587b7d 100644
--- a/helm/software/components/extlib/hExtlib.ml
+++ b/helm/software/components/extlib/hExtlib.ml
@@ -164,6 +164,23 @@ let rec list_forall_default3 f l1 l2 def l3 =
     | a::ta, b::tb, [] -> f a b def && list_forall_default3 f ta tb def [] 
 ;;
 
+exception FailureAt of int;;
+
+let list_forall_default3_var f l1 l2 def l3 = 
+  let rec aux f l1 l2 def l3 i =
+    match l1,l2,l3 with
+      | [], [], _ -> true
+      | [], _, _
+      | _, [], _ -> raise (Invalid_argument "list_forall_default3")
+      | a::ta, b::tb, c::tc -> 
+      	  if f a b c then aux f ta tb def tc (i+1)
+	  else raise (FailureAt i)
+      | a::ta, b::tb, [] ->
+      	  if f a b def then aux f ta tb def [] (i+1)
+	  else raise (FailureAt i)
+  in aux f l1 l2 def l3 0
+;;
+
 let sharing_map f l =
   let unchanged = ref true in
   let rec aux b = function
@@ -522,6 +539,7 @@ let rec mk_list x = function
 ;;
 
 let list_seq start stop =
+  if start > stop then [] else
   let rec aux pos =
     if pos = stop then []
     else pos :: (aux (pos+1))
@@ -529,3 +547,10 @@ let list_seq start stop =
     aux start
 ;;
 
+let rec list_skip n l =
+  match n,l with
+  | 0,_ -> l
+  | n,_::l -> list_skip (n-1) l
+  | _, [] -> assert false
+;;
+