The next code snippet

$case [1, 2, 3]
   $of x:xs
      #{x}
      $forall y <- xs
         , #{y}

causes an error:

unexpected ":"
expecting letter or digit, "_", "'", " ", "@", "," or ")"

The pattern of empty list [] is supported, but the support for compound list constructor (:) is not. Is it a bug or a feature? It is possible to make a workaround, using $if clause, but the case pattern seems to be more natural here.