SAFE: a Foldable proposal

[Kosyrev Serge]

Thomas Tuegel <ttuegel at gmail.com> writes:
> On Thu, Feb 25, 2016 at 3:32 PM, Kosyrev Serge
> <_deepfire at feelingofgreen.ru> wrote:
>> What about adding unstructural fold/traversal under different names?
>>
>> That way we could have the convenience when we truly don't care about
>> the directionality property, and the benefits of pure folding at the
>> same time.
>
> That's a good idea, but I don't think it really changes anything. The
> chief problem with types that aren't structurally ordered is really
> that there are multiple valid orders. For example, if [a] is our
> canonical structurally-ordered type, there are at least two obvious
> ways to write f :: Ord a => Set a -> [a]. I don't think an
> unstructured version of Foldable has much benefit over simply
> converting the improper type to a proper one.

Just off the top of my head -- efficiency?  Or is that overhead imaginary?

-- 
с уважениeм / respectfully,
Косырев Сергей