Take the &env from a macro, and tell whether we are expanding into cljs.

Return then if we are generating cljs code and else for Clojure code.
https://groups.google.com/d/msg/clojurescript/iBY5HaQda4A/w1lAQi9_AwsJ

Returns true iff arg is a native Java or JavaScript array.

A cross-platform variant of try-catch that catches all exceptions.
Does not (yet) support finally, and does not need or want an exception class.

Returns the type/class name of a value as a string.  Works for both CLJ and CLJS.