Greetings. I’m busy using `zipOrAccumulate` to compose smart constructors however this function as a...

# arrow

[Kev]

Greetings. I’m busy using zipOrAccumulate to compose smart constructors however this function as a maximum raise accumulation of 9 actions. Is there a strategy I can apply to increase the accumulation size?

[Alejandro Serrano.Mena]

you can nest them using a combination of tuples in the middle stages, and destructuring in the last onr:

zipOrAccumulate(
  zipOrAccumulate(
    thing1, thing2, thing3, thing4,
    ::Tuple4
  ),
  zipOrAccumulate(
    thing5, thing6, thing7, thing8,
    ::Pair4
  )
) { (x1, x2, x3, x4), (x5, x6, x7, x8) -> ... }

[Kev]

Not ideal but it’ll solve my problem. Thanks!

[Youssef Shoaib [MOD]]

You can of course always Ctrl+B to go to declaration, and then copy the code and increase the parameter size.

[Kev]

@Youssef Shoaib [MOD] some of the types are package private / internal. I’m tempted to do a PR with increased parameter size variants.

[Kev]

I’ve created a PR (https://github.com/arrow-kt/arrow/pull/3297) to add more parameter variants of zipOrAccumulate. I’ve noticed that the 2.0.0 milestone has reduced Tuples to Tuple9. I hope this won’t effect the span of zipOrAccumulate parameter lengths.

[Alejandro Serrano.Mena]

we actually dropped at some point from 10 to 22 because it led to issues with binary size

[Kev]

That’s understandable. Please action the PR accordingly 👍

[Youssef Shoaib [MOD]]

Maybe an extra library could be provided with larger parameter sizes? Or some of the primitives for writing a zipOrAccumulate and the like could be made public so people can roll their own higher arity versions

[Kev]

This is a great idea. If the primitives were made publicly available, an extra library could be created to cater for such things, along with larger tuples, etc. Thoughts?

[Alejandro Serrano.Mena]

the primitives are there: you just need to nest several zipOrAccumulate, using Tuples (or any other type you like) as intermediate steps

[Kev]

That’s what I ended up doing. Personally, I find this to be rather ugly 😞