This doesn't even begin to get into the question of what Levenshtein Distance even means in a Unicode context. What's the Levenshtein Distance of 3 emoji flags? I suppose we should be segmenting by grapheme clusters and utilizing a consistent normalization form when comparing, but Rust has no native support for processing grapheme clusters -- or for normalizations I believe. The UnicodeSegementation crate might help.
Based on some cursory research, the go version differs in a more subtle way too. A Rune is a Code Point, which is a superset of the Rust "char" type; it includes surrogate pairs.
Based on some cursory research, the go version differs in a more subtle way too. A Rune is a Code Point, which is a superset of the Rust "char" type; it includes surrogate pairs.