- Small improvement to overlap testing for intervals.

1 files changed, 16 insertions, 16 deletions

diff --git a/stdlib/source/lux/control/interval.lux b/stdlib/source/lux/control/interval.lux
index 95a23c378..16a78e282 100644
--- a/stdlib/source/lux/control/interval.lux
+++ b/stdlib/source/lux/control/interval.lux
@@ -163,22 +163,22 @@
 (def: #export (overlaps? reference sample)
   (All [a] (-> (Interval a) (Interval a) Bool))
   (let [(^open) reference]
-    (cond (singleton? sample)
-          false
+    (and (not (:: Eq<Interval> = reference sample))
+         (cond (singleton? sample)
+               false
 
-          (singleton? reference)
-          (and (>= (:: sample bottom) (:: reference bottom))
-               (<= (:: sample top) (:: reference top)))
+               (singleton? reference)
+               (nested? sample reference)
 
-          (or (and (inner? sample) (outer? reference))
-              (and (outer? sample) (inner? reference)))
-          (or (>= (:: reference bottom) (:: sample top))
-              (<= (:: reference top) (:: sample bottom)))
-          
-          (inner? sample)
-          (and (not (:: Eq<Interval> = reference sample))
-               (inner? (intersection reference sample)))
+               (or (and (inner? sample) (outer? reference))
+                   (and (outer? sample) (inner? reference)))
+               (or (>= (:: reference bottom) (:: sample top))
+                   (<= (:: reference top) (:: sample bottom)))
+
+               ## both inner
+               (inner? sample)
+               (inner? (intersection reference sample))
 
-          ## (outer? sample)
-          (not (:: Eq<Interval> = reference sample))
-          )))
+               ## both outer
+               (not (nested? reference sample))
+               ))))