[swift-evolution] InternalString class for easy String manipulation

[Félix Cloutier]

> In Félix’s case, I would expect to have to ask for a mail-friendly representation of his name, just like you have to ask for a filesystem-friendly representation of a filename regardless of what the internal representation is. Just because you are using UTF-8 as the internal format, it does not mean that universal support is guaranteed.

Would you imagine if "n" turned out to be poorly supported by systems throughout the world and dead-serious people argued that it's too hard for beginners?

"Filesystem-friendly" and "email-friendly" names are not backed by modern standards. You can have essentially any character that you like in a file name save for the directory separator on almost every platform out there (except on Windows, but the constraints are implemented in a layer above NTFS), and addresses like félix at ... are RFC-legal. Restrictions are merely wished into existence by programmers who don't want to complicate their mental model of text processing, to everyone else's detriment.

Félix