[winterlight]

What bothers me most about clojure is the abstraction leak when it comes to errors. When something goes wrong (say you passed a value of wrong datatype to a function), it just spits a java error stack. I'd like to have feedback closer to the conceptual level of the language, than to the intricacies of the run-time.

[escherize]

Spec instrumentation solves this perfectly for Clojure and ClojureScript. There's a price to pay, sure. Namely speccing your functions, but specs are defined for the functions in clojure.core.

[bogomipz]

I am curious is this true for all other JVM-hosted languages as well?

I've only ever been exposed to Clojure. Does Scala and JRuby have this as well?