From 052e607c5c32555ca5ad2ea2c903e18bb64e76c7 Mon Sep 17 00:00:00 2001
From: Calascibetta Romain <romain.calascibetta@gmail.com>
Date: Mon, 21 Jan 2019 18:41:53 +0100
Subject: [PATCH] CCFQueue.t must be covariant

---
 src/data/CCFQueue.ml  | 4 ++--
 src/data/CCFQueue.mli | 2 +-
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/src/data/CCFQueue.ml b/src/data/CCFQueue.ml
index dbdedc53..61e1cc98 100644
--- a/src/data/CCFQueue.ml
+++ b/src/data/CCFQueue.ml
@@ -22,14 +22,14 @@ type one = zero succ
 type two = zero succ succ
 type three = zero succ succ succ
 
-type ('a, 'l) digit =
+type (+'a, 'l) digit =
   | Zero : ('a, zero) digit
   | One : 'a -> ('a, one) digit
   | Two : 'a * 'a -> ('a, two) digit
   | Three : 'a * 'a * 'a -> ('a, three) digit
 
 (* store the size in deep version *)
-type 'a t =
+type +'a t =
   | Shallow : ('a, _) digit -> 'a t
   | Deep : int * ('a, _ succ) digit * ('a * 'a) t lazy_t * ('a, _ succ) digit -> 'a t
 
diff --git a/src/data/CCFQueue.mli b/src/data/CCFQueue.mli
index 44a7c8ac..4fce8b7d 100644
--- a/src/data/CCFQueue.mli
+++ b/src/data/CCFQueue.mli
@@ -10,7 +10,7 @@ type 'a printer = Format.formatter -> 'a -> unit
 
 (** {2 Basics} *)
 
-type 'a t
+type +'a t
 (** Queue containing elements of type 'a *)
 
 val empty : 'a t