CouchDB delegates computation of Views to external query servers. So it is possible to use other languages than Javascript for MapReduce functions (for example, there is implementations for Common Lisp, native Erlang, etc.)
Is it possible to do so with CouchDB Show/List functions?
Yes it is possible (even on a per-view basis) and is described on this page of the CouchDB wiki:
http://wiki.apache.org/couchdb/View_server
Once you define additional query servers in your local.ini you're good to go and even Futon (the included /_utils web interface) will give you a dropdown to select a language from.