
mc21.hs:12:26:
    Couldn't match type `a' with `[a]'
      `a' is a rigid type variable bound by
          a type expected by the context: [a] -> [[a]] at mc21.hs:12:9
    Expected type: [a] -> [[a]]
      Actual type: [a] -> [a]
    In the return type of a call of `take'
    In the expression: take 5
