nextEasiness :: Easiness -> Quality -> Easiness
nextEasiness e q = maximum [ne, 1.3]
  where ne = e - 0.8 + 0.28 * ql - 0.02 * ql * ql
        ql = qualityLevel q
nextEasiness :: Easiness -> Quality -> Easiness
nextEasiness e q = maximum [ne, 1.3]
  where ne = e - 0.8 + 0.28 * ql - 0.02 * ql * ql
        ql = qualityLevel q
nextEasiness e q = maximum [ne, 1.3]
  where ne = e - 0.8 + 0.28 * ql - 0.02 * ql * ql
        ql = qualityLevel q