1 files changed, 25 insertions, 12 deletions
diff --git a/stdlib/source/library/lux/data/collection/dictionary/plist.lux b/stdlib/source/library/lux/data/collection/dictionary/plist.lux
index d646287c8..7eb2f4001 100644
--- a/stdlib/source/library/lux/data/collection/dictionary/plist.lux
+++ b/stdlib/source/library/lux/data/collection/dictionary/plist.lux
@@ -1,16 +1,17 @@
 (.using
-  [library
-   [lux "*"
-    [abstract
-     [equivalence {"+" Equivalence}]]
-    [data
-     ["[0]" product]
-     ["[0]" text ("[1]#[0]" equivalence)]
-     [collection
-      ["[0]" list ("[1]#[0]" functor)]]]
-    [math
-     [number
-      ["n" nat]]]]])
+ [library
+  [lux "*"
+   [abstract
+    [equivalence {"+" Equivalence}]
+    [monoid {"+" Monoid}]]
+   [data
+    ["[0]" product]
+    ["[0]" text ("[1]#[0]" equivalence)]
+    [collection
+     ["[0]" list ("[1]#[0]" functor mix)]]]
+   [math
+    [number
+     ["n" nat]]]]])
 
 ... https://en.wikipedia.org/wiki/Property_list
 (type: .public (PList a)
@@ -97,3 +98,15 @@
   (All (_ a) (-> (Equivalence a) (Equivalence (PList a))))
   (|>> (product.equivalence text.equivalence)
        list.equivalence))
+
+(implementation: .public monoid
+  (All (_ a) (Monoid (PList a)))
+
+  (def: identity
+    ..empty)
+
+  (def: (composite left right)
+    (list#mix (function (_ [key val] it)
+                (..has key val it))
+              right
+              left)))