In many languages it's difficult fixing the string type without breaking existing code. In Ruby: String#upcase only handles ASCII (by spec), #length counts codepoints, #reverse reverses codepoints.

You can use UnicodeUtils if you need "full" Unicode support:

    >> UnicodeUtils.upcase("baffle")
    => "BAFFLE"
    >> graphemes = UnicodeUtils.each_grapheme("noe\u0308l").to_a
    >> graphemes.reverse.join
    => "lëon"
    >> graphemes.size
    => 4
    >> graphemes[0, 3]
    => "noë"