When talking about manipulating strings, it doesn't hurt to look at Perl, one of the great string-manipulating languages. Although Perl promotes its deeply-integrated regexes as the primary string manipulation mechanism, it also provides a free function to do indexed slicing of strings, substr($x, offset, length). Although it isn't O(1) and doesn't use subscript syntax or otherwise feel "first class", that hasn't been a huge deal. Javascript similarly has substr[ing] methods on its string type. Maybe we could take the same tack in Swift; spelling the offset-based accessor as .substr(x, y) instead of as a subscript would let us offer the easy thing for the times you really need it, while still signaling that, since this isn't a subscript, it isn't intended to be the primary primitive way you decompose strings.
7 Likes