Proposal: Add foldrWithIndex and foldlWithIndex to Data.List

[David Feuer]

Yes, they do. In particular, the zip can only fuse with one of the two
lists so the Ints could be unboxed, or fusion optimizations could happen
with the list folded over, but not both. The fold_WithIndex function can
manage both at once. That said, I think there have been some pretty good
arguments against adding these, or at least against adding them with these
names.
On Oct 22, 2014 3:13 PM, "Ganesh Sittampalam" <ganesh at earth.li> wrote:

> On 16/10/2014 18:14, David Feuer wrote:
>
>> These functions can be lifted pretty much straight out of Data.Sequence.
>> In particular, foldrWithIndex makes for a particularly nice expression
>> of a fusing findIndices function, as is present in Data.Sequence.
>>
>
> Do these do anything better than just adding indicies first with the
> standard zip [0..] idiom?
>
> Cheers,
>
> Ganesh
>
> _______________________________________________
> Libraries mailing list
> Libraries at haskell.org
> http://www.haskell.org/mailman/listinfo/libraries
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://www.haskell.org/pipermail/libraries/attachments/20141022/a4a89d77/attachment.html>