[Manishearth]

> The standard library also includes Path/PathBuf and OsStr/OsString.

Right. And you want people to explicitly convert between them.

Having to convert between string types isn't a problem. String encoding is hard, and you're going to have to pay that cost somehow.

[JoshTriplett]

Having to convert isn't a problem. Having to write some algorithms multiple times for different string types is a problem.

[Manishearth]

Fair. Most of these algorithms could be written generically I guess.