From 6ceaf0176b2a61cd2ed7b358af1e34349a8041ce Mon Sep 17 00:00:00 2001
From: Hugo Herbelin
Date: Fri, 19 May 2017 21:14:36 +0200
Subject: Moving "sym" on "eq" type to lib/util.ml.

---
 lib/util.ml  | 2 ++
 lib/util.mli | 2 ++
 2 files changed, 4 insertions(+)

(limited to 'lib')

diff --git a/lib/util.ml b/lib/util.ml
index 0d2425f271..36282b2dac 100644
--- a/lib/util.ml
+++ b/lib/util.ml
@@ -136,6 +136,8 @@ type ('a, 'b) union = ('a, 'b) CSig.union = Inl of 'a | Inr of 'b
 type 'a until = 'a CSig.until = Stop of 'a | Cont of 'a
 type ('a, 'b) eq = ('a, 'b) CSig.eq = Refl : ('a, 'a) eq
 
+let sym : type a b. (a, b) eq -> (b, a) eq = fun Refl -> Refl
+
 module Union =
 struct
   let map f g = function
diff --git a/lib/util.mli b/lib/util.mli
index cf8041a0d9..56ec5394eb 100644
--- a/lib/util.mli
+++ b/lib/util.mli
@@ -133,5 +133,7 @@ type 'a until = 'a CSig.until = Stop of 'a | Cont of 'a
 
 type ('a, 'b) eq = ('a, 'b) CSig.eq = Refl : ('a, 'a) eq
 
+val sym : ('a, 'b) eq -> ('b, 'a) eq
+
 val open_utf8_file_in : string -> in_channel
 (** Open an utf-8 encoded file and skip the byte-order mark if any. *)
-- 
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