From 4b409ca34fb1885eaf9508dc85481cb697209380 Mon Sep 17 00:00:00 2001
From: Simon Cruanes <simon.cruanes.2007@m4x.org>
Date: Sat, 21 Mar 2015 16:10:48 +0100
Subject: [PATCH] bugfix in CCFQueue.add_seq_front

---
 src/data/CCFQueue.ml | 17 ++++++++++-------
 1 file changed, 10 insertions(+), 7 deletions(-)

diff --git a/src/data/CCFQueue.ml b/src/data/CCFQueue.ml
index 831f88a7..0f828d8c 100644
--- a/src/data/CCFQueue.ml
+++ b/src/data/CCFQueue.ml
@@ -290,9 +290,15 @@ let tail q =
 *)
 
 let add_seq_front seq q =
-  let q = ref q in
-  seq (fun x -> q := cons x !q);
-  !q
+  let l = ref [] in
+  (* reversed seq *)
+  seq (fun x -> l := x :: !l);
+  List.fold_left (fun q x -> cons x q) q !l
+
+(*$Q
+  Q.(pair (list int) (list int)) (fun (l1, l2) -> \
+    add_seq_front (Sequence.of_list l1) (of_list l2) |> to_list = l1 @ l2)
+  *)
 
 let add_seq_back q seq =
   let q = ref q in
@@ -377,10 +383,7 @@ let to_list q =
   to_seq q (fun x -> l := x :: !l);
   List.rev !l
 
-let of_seq seq =
-  let l = ref [] in
-  seq (fun x -> l := x :: !l);
-  List.fold_left (fun q x -> cons x q) empty !l
+let of_seq seq = add_seq_front seq empty
 
 (*$Q
   (Q.list Q.int) (fun l -> \