peek back instead of reconstructing all of history

bytes-zone · Sep 25, 2020 · 9f68d32 · 9f68d32
1 parent e2a5b7f
commit 9f68d32
Show file tree

Hide file tree

Showing 2 changed files with 7 additions and 3 deletions.
diff --git a/src/History.elm b/src/History.elm
@@ -1,4 +1,4 @@
-module History exposing (History, current, goBack, init, mapPush, push)
+module History exposing (History, current, goBack, init, mapPush, peekBack, push)
 
 {-| -}
 
@@ -45,6 +45,11 @@ mapPush fn history =
     push (fn (current history)) history
 
 
+peekBack : History a -> Maybe a
+peekBack (History guts) =
+    List.head guts.past
+
+
 goBack : History a -> Maybe (History a)
 goBack (History guts) =
     case guts.past of

diff --git a/src/Main.elm b/src/Main.elm
@@ -377,8 +377,7 @@ rankings : Model -> Html Msg
 rankings model =
     let
         previousStandings =
-            History.goBack model.history
-                |> Maybe.map History.current
+            History.peekBack model.history
                 |> Maybe.withDefault (History.current model.history)
                 |> League.players
                 |> List.sortBy (\player -> -player.rating)