Right, so how do you get from Ruby strings (various encodings) to a Rust string? The sample code just calls std::str::from_utf8_unchecked(s) which is obviously not dealing with Ruby encodings.
All strings have encodings. It is not possible to represent a string which is a series of bytes except with encodings. I guess you probably mean default encoding or no encoding support... which implies ASCII, better known as US-ASCII.
In the high-level language I am most familiar with (Common Lisp), strings do not have encodings because they are vectors of characters, not vectors of bytes. How the string is actually stored in memory is an implementation detail.
Encoding is purely an artifact of I/O if your language has a character type that can represent all possible characters you might want read or write.
Rust's strings are almost this; if there were no way to get a string's raw representation, nor perform bytewise slices, then how the string was stored in RAM would be an implementation detail rather than part of the public API. Rust, being a systems language, probably does need to specify this so that it doesn't incur encode/decode overhead when dealing with foreign code that can understand utf-8.
