[Haskell] Help-me read file

Hello I have a file with 100 lists, with 100 ints. I have to read the file and apply the map and sort functions on lists. II did it to read file: learquivo :: FilePath -> IO ([[Int]]) learquivo s = do            conteudo <- readFile s            return (read conteudo) But now applying the sort, the error appears: <interactive>:1:5:    Couldn't match expected type `[a]'           against inferred type `IO [[Int]]' how can I fix? Thanks