FWIW, I think getting the underlying string representation right (and relatedly how it interacts with byte buffers&#x2F;slices) is really hard.  So far, I think Perl 6 probably has the most well thought out structure with regard to that, but they took a decade and a half and <i>lots</i> of testing to come up with what they did.  Then again, how it works in Perl 6 is also a function of how the language functions, so it wouldn&#x27;t be a a direct mapping of concepts, but there are some really good ideas there.