multi sub infix:<at> ($dsc, Code $deref) {
  $deref($dsc);
}

my %data = ( foo => [ { quux => 3 }, { bar => { baz => [ 1, 2, 3, 4 ] }, }, ], );

my $dereferencer = { .<foo>[1]<bar><baz>[3] };

say %data at $dereferencer;