Not to change the conversation but that's the same way you do it in PyMongo[1], I agree it looks bit un-pythonic.

[1] http://api.mongodb.org/python/1.9%2B/examples/map_reduce.htm...

If you have m-r code in your application, codify those functions, store them separately in a directory or even Riak objects, and refer to them by name in your code. Or, better yet, write it in Erlang.