Equipping extended maps with fold operator defined for any monad.

1 files changed, 15 insertions, 0 deletions

diff --git a/lib/cMap.mli b/lib/cMap.mli
index 23d3801e0..cd3d2f5b1 100644
--- a/lib/cMap.mli
+++ b/lib/cMap.mli
@@ -14,6 +14,13 @@ sig
   val compare : t -> t -> int
 end
 
+module type MonadS =
+sig
+  type +'a t
+  val return : 'a -> 'a t
+  val (>>=) : 'a t -> ('a -> 'b t) -> 'b t
+end
+
 module type S = Map.S
 
 module type ExtS =
@@ -59,6 +66,14 @@ sig
         i.e.: for all (k : key) (x : 'a), compare (fst (f k x)) k = 0. *)
   end
 
+  module Monad(M : MonadS) :
+  sig
+    val fold : (key -> 'a -> 'b -> 'b M.t) -> 'a t -> 'b -> 'b M.t
+    val fold_left : (key -> 'a -> 'b -> 'b M.t) -> 'a t -> 'b -> 'b M.t
+    val fold_right : (key -> 'a -> 'b -> 'b M.t) -> 'a t -> 'b -> 'b M.t
+  end
+  (** Fold operators parameterized by any monad. *)
+
 end
 
 module Make(M : Map.OrderedType) : ExtS with