A while ago, I put together foldable-seq, which allows fold to parallelize over lazy sequences:
https://groups.google.com/d/msg/clojure/8RKCjF00ukQ/b5mmmOB5Uh4J
As suggested by Stuart, I'm now looking at what I need to do to propose a patch. To that end, I'm trying to work out how to test it and have been looking to see what tests there already are for fold. But I'm coming up blank - I can't find any existing tests for fold (well, apart from test-nil in test-clojure.reducers, but that only tests a very specific corner case).
Am I missing something?