[irogers]

String should be an interface/protocol. When I log a message, I want to pass a string. If I have to append large strings for a log message I don't want to run out of memory, I should be able to pass a rope/cord [1]. We've known how to abstract this for forever and should work to optimize our compilers/runtimes accordingly. I'm not aware of a language which has got this right, for example, Java has the ugly CharSequence interface that nobody uses. StringProtocol in Swift (can I implement it?) makes you pay a character tax rather than to just pass a string. Rust/C++ give various non-abstracted types.

[1] https://en.wikipedia.org/wiki/Rope_(data_structure)

[pdimitar]

Erlang/Elixir's iolists which are heavily utilized in Phoenix's templating engine are a rope and are extremely efficient (for a dynamic language). Phoenix's templating is very fast.

[60secz]

Can't agree more. Java in particular suffers greatly from Object toString with a weak contract and no global String interface. If String were an interface instead of an implementation than any method signature could accept multiple implementations. This allows for really effective type aliases which even support strong typing so if you have a signature with multiple String values you can use the strong types to ensure you don't transpose arguments.