Use a sensible definition for the all volumes positive test.

diff --git a/src/Cube.hs b/src/Cube.hs
index 3a997a4ab25e917eccd7e9e18587589b7bc98a32..1144a13168d7041800d67e18876d2e4dd369cdc7 100644 (file)
--- a/src/Cube.hs
+++ b/src/Cube.hs
@@ -665,15 +665,15 @@ prop_opposite_octant_tetrahedra_disjoint6 cube =
 
 
 -- | Since the grid size is necessarily positive, all tetrahedra
---   (which comprise cubes of positive volume) must have positive volume
---   as well.
+--   (which comprise cubes of positive volume) must have positive
+--   volume as well.
 prop_all_volumes_positive :: Cube -> Bool
 prop_all_volumes_positive cube =
-    null nonpositive_volumes
+    all (>= 0) volumes
     where
       ts = tetrahedra cube
       volumes = map volume ts
-      nonpositive_volumes = filter (<= 0) volumes
+
 
 -- | In fact, since all of the tetrahedra are identical, we should
 --   already know their volumes. There's 24 tetrahedra to a cube, so