Or to be even more concise, use the notation you showed earlier: 
use v6;

foo( :B<there>, :A<howdy> );

sub foo(Str :$A, Str :$B){
        say "Named parameter A is '$A'";
        say "Named parameter B is '$B'";

}

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In reply to Re^7: Perl 6, defining a hash with interpolated string by molecules
in thread Perl 6, defining a hash with interpolated string by Mr_Micawber

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