perf improvements, mobile working on i4s

desktop/src-common/advent/zone.clj

@@ -1,7 +1,14 @@
 (ns advent.zone)
 
+(defn within [x1 y1 x2 y2 x3 y3]
+  (and
+   (< x1 x3)
+   (< x3 x2)
+   (< y1 y3)
+   (< y3 y2)))
+
 (defn box [x1 y1 x2 y2]
   (fn [x y]
-    (and
-     (< x1 x x2)
-     (< y1 y y2))))
+    (within x1 y1 x2 y2 x y)))
+
+