Proposal: Add a catamorphism on Trees

[Edward Kmett]

Interestingly, I just noticed I'm missing a similar combinator in `free`
for the Cofree comonad.

https://github.com/ekmett/free/issues/136

On Wed, May 18, 2016 at 11:32 AM, Tikhon Jelvis <tikhon at jelv.is> wrote:

> I was just thinking about refactoring some code to a tree fold—I had
> assumed it was in the library already, and only realized it wasn't when I
> saw this thread.
>
> Definite +1.
> On May 18, 2016 8:28 AM, <amindfv at gmail.com> wrote:
>
>> +1
>>
>> Tom
>>
>>
>> El 18 may 2016, a las 08:55, Jake McArthur <jake.mcarthur at gmail.com>
>> escribió:
>>
>> +1 from me as well. I think I'm unlikely to ever turn down a
>> straightforward catamorphism or anamorphism.
>>
>> On Wed, May 18, 2016, 8:52 AM Alp Mestanogullari <alpmestan at gmail.com>
>> wrote:
>>
>>> +1, have implemented it in a few occasions already.
>>>
>>> On Tue, May 17, 2016 at 11:03 PM, David Feuer <david.feuer at gmail.com>
>>> wrote:
>>>
>>>> Daniel Wagner would like to add the following straightforward function
>>>> to Data.Tree. I think this is a grand idea.
>>>>
>>>> foldTree :: (a -> [b] -> b) -> Tree a -> b
>>>> foldTree f = go
>>>>   where
>>>>     go (Node x ts) = f x (map go ts)
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>>>
>>>
>>>
>>> --
>>> Alp Mestanogullari
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