foldComments :: (CommentId -> Maybe ChapterId -> Comment -> b -> b) -> b
             -> B.ByteString -> IO b
foldComments f =
    foldLogFile $ \act ->
    case act of
      AddChapter _ _ _       -> return
      AddComment cId mChId c -> \x -> let x' = f cId mChId c x
                                      in  x' `seq` return x'
foldComments :: (CommentId -> Maybe ChapterId -> Comment -> b -> b) -> b
             -> B.ByteString -> IO b
foldComments f =
    foldLogFile $ \act ->
    case act of
      AddChapter _ _ _       -> return
      AddComment cId mChId c -> \x -> let x' = f cId mChId c x
                                      in  x' `seq` return x'
foldComments f =
    foldLogFile $ \act ->
    case act of
      AddChapter _ _ _       -> return
      AddComment cId mChId c -> \x -> let x' = f cId mChId c x
                                      in  x' `seq` return x'