Clojure:
Clojure 1.8.0
user=> (/ 3 4)
3/4
cljs.user=> (/ 3 4)
0.75
Common Lisp implementations OTOH implement most of the standard. There is also more choice in implementations:
* native implementations AND hosted implementations
* actual Lisp interpreters or a mix of interpreters and compilers, interactive compilers, batch compiler
* compilers written in Lisp itself with good error messages, forms of compile-time type checking/inference, and advanced error handling (like SBCL, CMUCL)
* compilation to C, full embedding into C programs (ECL and others)
* full embedding in C++ (CLASP)
* compilation to shared libraries, embeddable into other applications
* whole program compilers for delivery of compact applications (like mocl)
The main Clojure compiler is written in Java and it shows...
https://github.com/clojure/clojure/blob/master/src/jvm/cloju...
If one targets a certain host environment (JVM, Javascript, ...) then this range of options and choice might not matter, even hinder - besides getting a poorer version of interactivity.
If we see a Lisp as a language on its own, then it matters a lot.
How does this help, compared to Clojure?
> Multiple mature implementations
Why wouldn't one free mature implementation be good enough?
> Wholeheartedly multi-paradigm
Exactly like Clojure.
> "Lisp-2" rather than "Lisp-1"
I can't remember which one Clojure is :) But I haven't had any problems with namespaces and the like.
> Designed for implementation in a wide variety of environments
So is Clojure, right? There's the CLR version, and ClojureScript too.