Add payments by month in stat

1 files changed, 13 insertions, 0 deletions

diff --git a/src/client/elm/Utils/List.elm b/src/client/elm/Utils/List.elm
new file mode 100644
index 0000000..85cdc24
--- /dev/null
+++ b/src/client/elm/Utils/List.elm
@@ -0,0 +1,13 @@
+module Utils.List
+  ( groupBy
+  ) where
+
+import Dict
+
+groupBy : (a -> comparable) -> List a -> List (comparable, List a)
+groupBy f xs =
+  let addItem item dict =
+        let groupItems = Dict.get (f item) dict |> Maybe.withDefault []
+        in  Dict.insert (f item) (item :: groupItems) dict
+  in  List.foldr addItem Dict.empty xs
+        |> Dict.toList