On 8/26/12 9:10 PM, Sebastien Zany wrote:
Thanks Wren. That was my guess too, but it seems not necessary: http://stackoverflow.com/questions/12103309/when-is-a-composition-of-catamorphisms-a-catamorphism
Well, sure. I was meaning in the general case. If you have the right kind of distributivity property (as colah suggests) then things will work out for the particular case. But, having the right kind of distributivity property typically amounts to being a natural transformation in some appropriately related category; so that just defers the question to whether an appropriately related category always exists, and whether we can formalize what "appropriately related" means.
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