$type->($value) is a live-or-die function rather than returning a boolean. It returns $value if it lives. Makes it easy to do something like:

sub set_name {
  my $self  = Object->( shift );
  my $value = Str->( shift );
  $self->{name} = $value;
}
sub get_name {
  my $self = Object->( shift );
  return $self->{name};
}
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$type->check($value) returns a boolean.

Exporting an is_Topping (boolean) or assert_Topping (live or die) function will be faster because it will avoid overhead from things like overloading, method lookups, etc. Though what you've already got is unlikely to be a major bottleneck for your application, so I'd mostly say go with what you feel is more readable.