- List ranges can now be generated backwards.

1 files changed, 11 insertions, 6 deletions

diff --git a/stdlib/source/lux/data/coll/list.lux b/stdlib/source/lux/data/coll/list.lux
index b9b743b2c..f6c19dcb9 100644
--- a/stdlib/source/lux/data/coll/list.lux
+++ b/stdlib/source/lux/data/coll/list.lux
@@ -303,16 +303,21 @@
                            xs')]
       ($_ compose (sort < pre) (list x) (sort < post)))))
 
-(do-template [<name> <type> <comp> <inc>]
+(do-template [<name> <type> <lt> <inc> <gt> <dec>]
   [(def: #export (<name> from to)
      {#.doc "Generates an inclusive interval of values [from, to]."}
      (-> <type> <type> (List <type>))
-     (if (<comp> to from)
-       (list& from (<name> (<inc> from) to))
-       (list)))]
+     (cond (<lt> to from)
+           (list& from (<name> (<inc> from) to))
 
-  [i/range Int i/<= i/inc]
-  [n/range Nat n/<= n/inc]
+           (<gt> to from)
+           (list& from (<name> (<dec> from) to))
+
+           ## (= to from)
+           (list from)))]
+
+  [i/range Int i/< i/inc i/> i/dec]
+  [n/range Nat n/< n/inc n/> n/dec]
   )
 
 (def: #export (empty? xs)