Racket is an excellent language for DSL’s, compilers, and interpreters. I’m not aware of any other language that has as sophisticated and powerful tooling as Racket in this regard.
It’s also really good for creating GUI’s.
As I wrote in a previous HN thread about Racket, I think Racket’s strong suit is developing internal company tooling that is run locally on an individual machine. Great as tooling for analysts, data scientists, etc.
I wouldn’t recommend Racket for a server unless it was serving relatively few requests. The JVM would probably be a better choice.
From just a quality stand point (documentation, libraries, design) Racket is undoubtedly the best and most advanced lisp on the market. From a practical standpoint, clojure might be better in many cases.
Edit: PS: Typed Racket is really quite nice, though I found it to be too restrictive to use all the time. In a language like Haskell you don’t really feel constrained by the type system since the language is designed around it. In Racket this isn’t the case so you quickly discover that the subset of correct programs with static typing is much much smaller than the subset of correct programs with dynamic typing.
Fortunately as you mentioned you can use gradual typing and everything works fine. My workflow when I used to use Racket for work was to write a module, putting the types as comments. Afterwards, I would attempt to make those types real, skipping over any functions in which it was too onerous.
Also, Racket has runtime contracts that can provide similiar (or more powerful) guarantees as static typing. Though you have to turn them off for production because they absolutely destroy performance (orders of magnitudes slower).
Typed Racket seems like a more cohesive language than Typescript while retaining the dynamic typing escape hatch, so I've been eyeing it for a while.