The beautiful thing about UTF-8 is that a lot of simple seemingly-ascii algorithms will will work correctly with unicode: as long as you define "correctly" in a

The beautiful thing about UTF-8 is that a lot of simple seemingly-ascii algorithms will will work correctly with unicode: as long as you define "correctly" in a way that ignores complicated unicode semantics. And we can often do that: for example a programming language could just ban non-ASCII characters everywhere but in string literals. But sadly, we do often need to care about all those complicated unicode character classes etc. And if we are talking explicitly about Unicode, then by default we should be considering the whole standard, not just the bits we like.