`cata`?

[eraserhd]

I'm teasing out transducers and processes for Avi. I have a pretty general context for catamorphisms here. I'm still reasoning through a few corner cases to make sure it's golden, but would you like it? This project seems like a good place for it to go.

[eraserhd]

Also, maybe annotate - I've broken out stuff that could be contributed here.

https://github.com/maitria/avi/blob/master/src/avi/xforms.clj

[cgrand]

I haven't thought enough about transducing trees. Well core Clojure itself is half-equipped for trees:

• zippers are generic but feel imperative,
• tree-seq always need some filtering and does no rebuilding
• clojure.walk has no open definition of what is a node.