Remodel model.selectedChord as Maybe Chord

Until the user presses play, we shouldn't display any chords.

website/sandbox/chord-drill-sergeant/src/Main.elm

@@ -18,7 +18,7 @@ type alias Model =
     , whitelistedChordTypes : List Theory.ChordType
     , whitelistedInversions : List Theory.ChordInversion
     , whitelistedNoteClasses : List Theory.NoteClass
-    , selectedChord : Theory.Chord
+    , selectedChord : Maybe Theory.Chord
     , isPaused : Bool
     , tempo : Int
     , firstNote : Theory.Note
@@ -42,8 +42,11 @@ type Msg
     | ToggleInversion Theory.ChordInversion
     | ToggleChordType Theory.ChordType
     | ToggleNoteClass Theory.NoteClass
+    | DoNothing
 
 
+{-| The amount by which we increase or decrease tempo.
+-}
 tempoStep : Int
 tempoStep =
     5
@@ -61,14 +64,6 @@ bpmToMilliseconds target =
     round (toFloat msPerMinute / toFloat target)
 
 
-cmajor : Theory.Chord
-cmajor =
-    { note = Theory.C4
-    , chordType = Theory.MajorDominant7
-    , chordInversion = Theory.Root
-    }
-
-
 {-| The initial state for the application.
 -}
 init : Model
@@ -97,7 +92,7 @@ init =
     , whitelistedChordTypes = chordTypes
     , whitelistedInversions = inversions
     , whitelistedNoteClasses = noteClasses
-    , selectedChord = cmajor
+    , selectedChord = Nothing
     , isPaused = True
     , tempo = 60
     , firstNote = firstNote
@@ -123,8 +118,11 @@ subscriptions { isPaused, tempo } =
 update : Msg -> Model -> ( Model, Cmd Msg )
 update msg model =
     case msg of
+        DoNothing ->
+            ( model, Cmd.none )
+
         NewChord chord ->
-            ( { model | selectedChord = chord }
+            ( { model | selectedChord = Just chord }
             , Cmd.none
             )
 
@@ -137,7 +135,7 @@ update msg model =
                             NewChord chord
 
                         ( Nothing, _ ) ->
-                            NewChord cmajor
+                            DoNothing
                 )
                 (Random.List.choose model.whitelistedChords)
             )
@@ -329,19 +327,36 @@ inversionCheckboxes inversions =
         )
 
 
+displayChord :
+    { debug : Bool
+    , chord : Theory.Chord
+    , firstNote : Theory.Note
+    , lastNote : Theory.Note
+    }
+    -> Html Msg
+displayChord { debug, chord, firstNote, lastNote } =
+    div []
+        [ if debug then
+            ChordInspector.render chord
+
+          else
+            span [] []
+        , p [] [ text (Theory.viewChord chord) ]
+        , case Theory.notesForChord chord of
+            Just x ->
+                Piano.render
+                    { highlight = x
+                    , start = firstNote
+                    , end = lastNote
+                    }
+
+            Nothing ->
+                p [] [ text "No chord to show" ]
+        ]
+
+
 view : Model -> Html Msg
 view model =
-    case Theory.notesForChord model.selectedChord of
-        Nothing ->
-            p [] [ text ("""
-                       We cannot render the chord that you provided because the
-                       notes that comprise the chord fall off either the upper
-                       or lower end of the piano.
-
-                       Chord:
-                       """ ++ Theory.inspectChord model.selectedChord) ]
-
-        Just x ->
     div []
         [ Tempo.render
             { tempo = model.tempo
@@ -358,17 +373,17 @@ view model =
 
           else
             span [] []
-                , if model.debug.inspectChord then
-                    ChordInspector.render model.selectedChord
-
-                  else
-                    span [] []
-                , p [] [ text (Theory.viewChord model.selectedChord) ]
-                , Piano.render
-                    { highlight = x
-                    , start = model.firstNote
-                    , end = model.lastNote
+        , case model.selectedChord of
+            Just chord ->
+                displayChord
+                    { debug = model.debug.inspectChord
+                    , chord = chord
+                    , firstNote = model.firstNote
+                    , lastNote = model.lastNote
                     }
+
+            Nothing ->
+                p [] [ text "No chord to display" ]
         ]