Am I correct in thinking that Frege cannot leverage on third-party java libraries? Clojure, another functional language built on JVM, has great support for this (possibly) missing feature.
The article at https://mmhelloworld.github.io/blog/2013/07/10/frege-hello-j... talks about this, but doesn't quite explain the proxy mechanism, it just points out an example.
Not quite true anymore. TO be sure, some (inline) java will still be needed.
Here is an example https://github.com/Frege/frege/blob/master/tests/comp/Issue2... which compiles to a class that implements java.util.Comparator. Instances thereof can be created from Frege by passing a custom comparision function and could be passed to Java.
The example would be useful in cases when you have Frege data in a Java collection and want to sort them. But it is merely there to show the possibilities.