Just a nitpick. Rust's char is really a 21 bit unicode scalar value (a code point without surrogates) using a 32-bit representation and indeed there are a lot o

Just a nitpick. Rust's char is really a 21 bit unicode scalar value (a code point without surrogates) using a 32-bit representation and indeed there are a lot of invalid char values in a 32-bit space. Utf-8 is a different encoding format for code points using variable width (1-4 bytes per).