Tacinterp: refactoring using Monad.

Adds a combinator List.map_right which chains effects from right to left.

2 files changed, 29 insertions, 1 deletions

diff --git a/lib/monad.ml b/lib/monad.ml
index 773f952def..a1508ae01c 100644
--- a/lib/monad.ml
+++ b/lib/monad.ml
@@ -32,9 +32,14 @@ module type S = sig
   (** List combinators *)
   module List : sig
 
-    (** [map f l] applies the monadic effect left to right. *)
+    (** [map f l] maps [f] on the elements of [l] in left to right
+        order. *)
     val map : ('a -> 'b t) -> 'a list -> 'b list t
 
+    (** [map f l] maps [f] on the elements of [l] in right to left
+        order. *)
+    val map_right : ('a -> 'b t) -> 'a list -> 'b list t
+
   end
 
 end
@@ -53,6 +58,23 @@ module Make (M:Def) : S with type +'a t = 'a M.t = struct
           map f l >>= fun l' ->
           return (a'::l')
 
+    let rec map_right f = function
+      | [] -> return []
+      | a::l ->
+          map f l >>= fun l' ->
+          f a >>= fun a' ->
+          return (a'::l')
+
   end
 
 end
+
+
+
+
+
+
+
+
+
+
diff --git a/lib/monad.mli b/lib/monad.mli
index 1f04cf5e0c..5c4f74e51d 100644
--- a/lib/monad.mli
+++ b/lib/monad.mli
@@ -32,8 +32,14 @@ module type S = sig
   (** List combinators *)
   module List : sig
 
+    (** [map f l] maps [f] on the elements of [l] in left to right
+        order. *)
     val map : ('a -> 'b t) -> 'a list -> 'b list t
 
+    (** [map f l] maps [f] on the elements of [l] in right to left
+        order. *)
+    val map_right : ('a -> 'b t) -> 'a list -> 'b list t
+
   end
 
 end