No, it's not "just an implementation detail". I don't want to get into the details here, but your assumption that having your strings in one encoding composed conceptually of code points in a different encoding is not necessarily the way to go. I was on a JCP expert committee that rejected that option for Java, but that doesn't mean it couldn't end up best for Arc. It's just not as easy a decision as you imply. There are alternative approaches with different pros and cons, and since these abstractions all leak, you need to make a cross-implementation decision so that you don't end up with different coding practices on different platforms. Plus all the other issues that Unicode presents that make parsing a challenge that might have implications for a language that is famous for parsing and rewriting its own source at runtime.... These could all be worked out through a vigorous discussion process among a diverse group large enough to make sure that the implications of each approach are understood, but Graham doesn't work that way.