Score.elm

{-| Calculate a score from the model
-}
score : Model -> ExerciseMark
score model =
  let
    -- Fold over the questions, accumulating a mark
    score' : Exercise -> Array QuestionState -> ExerciseMark
    score' exercise questionStates =
      let
        -- The folding function
        acc : (Question, QuestionState) -> ExerciseMark -> ExerciseMark
        acc (question, questionState) exerciseMark =
          let
            -- Get the score and update the mark
            score = QuestionDelegate.scoreQuestion question questionState
          in
          ExerciseMark.updateWithScore score exerciseMark
      in
      Array.Extra.zip exercise.questions questionStates
        |> Array.foldr acc ExerciseMark.new
  in
  model.exercise
    |> Maybe.map (\e -> score' e model.questionStates)
    |> Maybe.withDefault ExerciseMark.new