[tmtvl]

> The only way to know strcat, puts, and strlen exist is…to know that they exist.

Yes, and the only way to know that Vector and Hashtable exist is... to know that they exist.

> I also wanted compile-time attributes à la Rust/C# and there’s no clean way to add those to Lisp’s syntax without seriously cluttering it up

That's what declarations are for, a Lisp could have something like:

  (declare (type Foo bar)
           (derive Clone bar))
  (define bar
    (bar:from-string "Hello, World!"))

Or something like:

  (db:with-connection (con (db:get-connection my-database))
    (declare (db:read-only con))
    (db:query con
              :table "students"
              :where (> "score" 80)
              :sort-by "name"))

> Lisp is neat but it just doesn’t fit in the future of programming that Rust and C# have shown us.

C♯ and Rust are dead languages, you make a change and you have to recompile the entire program and restart it from scratch. You can't ask a running program things like 'how many users are connected at the moment?'. That isn't a future I would like to see.