Add Comparable.Operators

Signed-off-by: Etienne Millon <me@emillon.org>

src/stdune/comparable.ml

@@ -2,3 +2,41 @@ module type S = sig
   type t
   val compare : t -> t -> Ordering.t
 end
+
+module type OPS = sig
+  type t
+  val (=) : t -> t -> bool
+  val (>=) : t -> t -> bool
+  val (>) : t -> t -> bool
+  val (<=) : t -> t -> bool
+  val (<) : t -> t -> bool
+end
+
+module Operators (X : S) = struct
+  type t = X.t
+
+  let (=) a b =
+    match X.compare a b with
+    | Eq -> true
+    | Gt | Lt -> false
+
+  let (>=) a b =
+    match X.compare a b with
+    | Gt | Eq -> true
+    | Lt -> false
+
+  let (>) a b =
+    match X.compare a b with
+    | Gt -> true
+    | Lt | Eq -> false
+
+  let (<=) a b =
+    match X.compare a b with
+    | Lt | Eq -> true
+    | Gt -> false
+
+  let (<) a b =
+    match X.compare a b with
+    | Lt -> true
+    | Gt | Eq -> false
+end

src/stdune/comparable.mli

@@ -2,3 +2,14 @@ module type S = sig
   type t
   val compare : t -> t -> Ordering.t
 end
+
+module type OPS = sig
+  type t
+  val (=) : t -> t -> bool
+  val (>=) : t -> t -> bool
+  val (>) : t -> t -> bool
+  val (<=) : t -> t -> bool
+  val (<) : t -> t -> bool
+end
+
+module Operators (X : S) : OPS with type t = X.t