# ANN: Parallel \`for\` loops in FLoops.jl with composable and extensible fold-based API

**URL:** https://discourse.julialang.org/t/ann-parallel-for-loops-in-floops-jl-with-composable-and-extensible-fold-based-api/45390
**Category:** Package Announcements
**Tags:** parallel, multithreading, distributed, loops
**Created:** [August 22, 2020, 11:09pm UTC](https://discourse.julialang.org/t/ann-parallel-for-loops-in-floops-jl-with-composable-and-extensible-fold-based-api/45390 "2020-08-22T23:09:56Z")
**Posts on this page:** 1
**Showing post:** 18

<div class="post-metadata">

### Author: ![c42f](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/c42f/32/52842_2.png) [@c42f](https://discourse.julialang.org/u/c42f)
#### Post date: [August 25, 2020, 11:50pm UTC](https://discourse.julialang.org/t/ann-parallel-for-loops-in-floops-jl-with-composable-and-extensible-fold-based-api/45390/18 "2020-08-25T23:50:27Z")

</div>

> [@tkf](#):
>
> But I’m guessing it’s probably possible already to make `fetch` inferable thanks to @c42f’s `_apply_in_world` builtin [https://github.com/JuliaLang/julia/pull/35844](https://github.com/JuliaLang/julia/pull/35844).

I originally thought we could have an API where the world counter and a function were wrapped up in a type and eventually fed to `_apply_in_world` which would be understood by inference. But @jameson seemed to think this would be unsound in some way. So for now I kept things simple and didn’t add any inference for `_apply_in_world`. I’d still like to do it though, or better understand why it’s not possible. There’s a small amount of discussion of this on the PR as well.

---

_[View the full topic](https://discourse.julialang.org/t/ann-parallel-for-loops-in-floops-jl-with-composable-and-extensible-fold-based-api/45390)._