sub echo(Int:D $x) {
    say $x.^name;
}

echo(Int);

--output:--
Parameter '$x' of routine 'echo' must be an object instance of type
'Int', not a type object of type 'Int'.  Did you forget a '.new'?
  in sub echo at b.raku line 14
  in block <unit> at b.raku line 18