From 0dfc87c68d5aba5adac079cb62ae504d82b303b9 Mon Sep 17 00:00:00 2001
From: Arnaud Spiwack
Date: Thu, 27 Feb 2014 14:50:40 +0100
Subject: Tacinterp: refactoring using Monad.

Adds a combinator List.map_right which chains effects from right to left.---
 lib/monad.ml  | 24 +++++++++++++++++++++++-
 lib/monad.mli |  6 ++++++
 2 files changed, 29 insertions(+), 1 deletion(-)

(limited to 'lib')

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
-- 
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