I don't think anyone will claim that any JVM language or node doesn't handily best Racket in terms of sheer numbers of libraries. What Racket does have are soli

I don't think anyone will claim that any JVM language or node doesn't handily best Racket in terms of sheer numbers of libraries. What Racket does have are solid core libraries with good docs. I don't know about "killer" but Racket's continuation based web server was / is novel (maybe first?). https://docs.racket-lang.org/web-server/ https://docs.racket-lang.org/web-server/ Also, it's not a library, but the whole #lang thing seems to be the coolest game in town for implementing DSLs and other more fully featured languages.