[Haskell] Deepseq

[Gilmara Pompelli]

Hello

How do I use deepseq, this function to force evaluation, the way I did
is correct?

um :: IO ()
um = do
    conteudo <- learquivo "mkList1.txt"
    mapasort <- return (mapa psort conteudo)
    time $   mapasort `deepseq`  return ()

Thanks