X-Git-Url: http://matita.cs.unibo.it/gitweb/?a=blobdiff_plain;f=helm%2Fsoftware%2Fcomponents%2Fextlib%2FhExtlib.ml;h=cccb467674e22415b59de320e72cbbe845812142;hb=571d199acd4e6743a48f8f64f28c62d18182d04d;hp=49d28bbb91733a50e785d3c17388a58cb7c7b32a;hpb=b0179e12340029c8316e3819c1f39171d878adc7;p=helm.git

diff --git a/helm/software/components/extlib/hExtlib.ml b/helm/software/components/extlib/hExtlib.ml
index 49d28bbb9..cccb46767 100644
--- a/helm/software/components/extlib/hExtlib.ml
+++ b/helm/software/components/extlib/hExtlib.ml
@@ -237,6 +237,18 @@ let filter_map_acc f acc l =
    acc, List.rev res
 ;;
 
+let filter_map_monad f acc l =
+  let acc, res = 
+   List.fold_left
+    (fun (acc, res) t ->
+       match f acc t with
+       | acc, None -> acc, res
+       | acc, Some x -> acc, x::res)
+    (acc,[]) l
+  in
+   acc, List.rev res
+;;
+
 let list_rev_map_filter f l =
    let rec aux a = function
       | []       -> a