The Go thing (+ invalid sequence conversion) is a really good point. If OP's point was "don't validate just convert invalid sequences when you need to" or "thin

The Go thing (+ invalid sequence conversion) is a really good point. If OP's point was "don't validate just convert invalid sequences when you need to" or "think twice before forcing validation into your primitive string type" I'd buy in. I also think your choice there to just write the invalid bytes out unchanged also makes a ton of sense. You're right that there's more options than "yolo no validate" or "validate or face death". > And believe you me, you'd see a lot more of that if I wasn't so careful to provide both `&str` and `&[u8]` APIs for all string oriented operations. ;-) Woof man yeah, that's what I was getting at with you're forcing people to basically implement things twice; it's not the best! This was a really good conversation; before this I was 100% in agreement w/ you on "'required UTF-8' is probably the better thing for a primitive string type" but now I see there's a fair amount of pragmatic issues with that. Definitely a lot to mull over here; thanks :)