expected

./badbangop.idr:7:1: error: ! is
    not a valid
    operator, expected: space
(!) : List a -> Nat -> Maybe a 
^                              
./baddoublebang.idr:6:28: error: unexpected
    Operator without known fixity:
    !!, expected: space
doubleBang mmn = do pure !!mmn 
                           ^