defaultFilterParam <- lookupGetParam "filter" let defaultFilterJson = (maybe Nothing (decode . LBS.fromChunks . (:[]) . encodeUtf8) defaultFilterParam) :: Maybe [FilterJsonMsg] defaultSortParam <- lookupGetParam "sort" let defaultSortJson = (maybe Nothing (decode . LBS.fromChunks . (:[]) . encodeUtf8) defaultSortParam) :: Maybe [SortJsonMsg]