Why does rayon not use tokio?

[isaac-weisberg]

I see that there is rayon-core, and I was almost under an impression that it pretty much just an multithreaded asynchronous programming runtime.

So it made me wonder, couldn't it be replaced by tokio?

[cuviper]

The simple answer is that rayon-core predates tokio, by several years. But rayon-core is not asynchronous in the sense of the language async and .await features, so I doubt it would work well within tokio's pool anyway.