I would say Swift has the best implementation. It actually conceptually treats strings as a group of grapheme clusters (the Character type is a grapheme cluster

I would say Swift has the best implementation. It actually conceptually treats strings as a group of grapheme clusters (the Character type is a grapheme cluster). This is more in line with how humans conceptually segment strings, and how most application logic should segment a string. > since now indexing requires scanning the string from start to end. This is not a good thing. O(1) code point indexing is a completely useless operation. Code points have no intrinsic meaning. They do not map to any natural language concept. They are just a tool to encode strings. The only time code points matter are when writing algorithms defined by the unicode spec, like casefolding. These operations usually require iteration anyway. If you're regularly indexing and slicing strings by code points, your code is likely broken when it comes across decomposed accents in European languages, most Asian languages, and emoji. FWIW you can have O(1) slice indexing in UTF8 as well; you just need to use byte position as your indexing type (and handle the error case when it's not aligned). Rust does this. It also has methods for working with char indices (and a .char_indices() iterator that lets you juggle the two), but byte indexing works. Generally these indices come from other parts of the application so you can design it to not have errors.