sub foo (
    $self,
                  # parameter declarations starting with '?' examine,
                  # but don't consume any further arguments:
                  
    ?*@args,      # @args is set to the equivalent of @_ with one
                  # arg shifted; i.e. like a slurpy but peeking ahead
                  # and not actually consuming any args; the '*' means
                  # that each @args element is aliased to a passed arg
                  
    ?$peek_a,     # $peek_a is bound to next arg but without consuming it
    ??$has_a,     # $has_a is set to true if there's an argument for $a
    $a,           # normal scalar parameter
    ?{ print $a },# embedded code block - runs code; doesn't shift args
                  
    Dog $spot,    # works the same as 'my Dog $spot'
    $b :shared,   # you can use normal variable attributes
    $c :ro,       # at compile time, $c in lvalue context croaks
                  
    \@ary,        # aliases @ary to a passed array reference
    \%hash,       # aliases %hash to a passed hash reference
    *$scalar,     # aliases $scalar to the next argument
                  
                  # Constraints and coercions:
    $d!,          #    croak if $d not defined
    $e isa Foo::Bar,
                  #    croak if $e isn't of that class
    $f is Int
      where $_ > 0,
                  #    croak if $f not a positive integer

    $x = 0,       # a default value
    $y?,          # short for $y = undef
    \@array?,     # short for \@array = []
                  
    :$name1 = 0,  
    :$name2 = 0,  # consume name-value pairs (name1 => ..., name2 => ....)
                  
    @rest         # slurp up any remaining arguments
) { .... }