From ea15b844b51ff60f9785c6791507f813729f85c3 Mon Sep 17 00:00:00 2001
From: Eduardo Julian
Date: Tue, 14 Sep 2021 03:21:21 -0400
Subject: Better list pairing.

---
 stdlib/source/test/lux/data/collection/list.lux | 19 ++++++++++++++++---
 1 file changed, 16 insertions(+), 3 deletions(-)

(limited to 'stdlib/source/test')

diff --git a/stdlib/source/test/lux/data/collection/list.lux b/stdlib/source/test/lux/data/collection/list.lux
index 5003567ee..a91db974f 100644
--- a/stdlib/source/test/lux/data/collection/list.lux
+++ b/stdlib/source/test/lux/data/collection/list.lux
@@ -281,8 +281,18 @@
        sample/2 ..random]
       ($_ _.and
           (_.cover [/.pairs]
-                   (n.= (n./ 2 (/.size sample/0))
-                        (/.size (/.pairs sample/0))))
+                   (let [even_sized? (|> sample/0
+                                         /.size
+                                         (n.% 2)
+                                         (n.= 0))]
+                     (case (/.pairs sample/0)
+                       {.#Some pairs/0}
+                       (and even_sized?
+                            (n.= (n./ 2 (/.size sample/0))
+                                 (/.size pairs/0)))
+
+                       {.#None}
+                       (not even_sized?))))
           (_.cover [/.zipped/2]
                    (let [zipped (/.zipped/2 sample/0 sample/1)
                          zipped::size (/.size zipped)
@@ -412,7 +422,10 @@
                            (let [sample+ (/.interposed separator sample)]
                              (and (n.= (|> (/.size sample) (n.* 2) --)
                                        (/.size sample+))
-                                  (|> sample+ /.pairs (/.every? (|>> product.right (n.= separator))))))))
+                                  (|> sample+
+                                      /.pairs
+                                      (maybe.else (list))
+                                      (/.every? (|>> product.right (n.= separator))))))))
               (_.cover [/.iterations]
                        (or (/.empty? sample)
                            (let [size (/.size sample)]
-- 
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