- Implemented Monoid for Duration.

1 files changed, 5 insertions, 0 deletions

diff --git a/stdlib/source/lux/time/duration.lux b/stdlib/source/lux/time/duration.lux
index 4537ba8d5..a91553544 100644
--- a/stdlib/source/lux/time/duration.lux
+++ b/stdlib/source/lux/time/duration.lux
@@ -3,6 +3,7 @@
   (lux (control eq
                 order
                 codec
+                [monoid #+ Monoid]
                 ["p" parser]
                 [monad #+ do])
        (data [number "int/" Codec<Text,Int> Number<Int>]
@@ -76,6 +77,10 @@
 (def: #export normal-year Duration (scale 365 day))
 (def: #export leap-year Duration (merge day normal-year))
 
+(struct: #export _ (Monoid Duration)
+  (def: identity empty)
+  (def: compose merge))
+
 (def: (encode duration)
   (-> Duration Text)
   (if (:: Eq<Duration> = empty duration)