Monad Comprehensions without coroutine about arrow-core HOT 3 CLOSED

Thanks for the answer ! Very happy to hear it is on the roadmap :) Looking forward to seeing it being rolled out. Great work.

from arrow-core.

@kalistace we agree and this is coming up for all data types that provide Monad around October https://github.com/47deg/arrow-meta-prototype/blob/rr-typeclasses-plugin/compiler-plugin/src/main/kotlin/arrow/meta/comprehensions/ComprehensionsPlugin.kt we are already working in a prototype that rewrites binds as flatMap because that is leaner than suspension. It will still use suspension for the code as it is today but will rewrite it to a nested flatMap

from arrow-core.

Hey @kalistace,

The overhead is neglectable of using suspend with the new planned encoding. It's a similar penalty as using a simple handwritten DSL, the compiler is leveraged to wire nested fold code together, and uses a cheap ControlThrowable to break out of the suspension.

(See Roman's example on using suspend for stack safe functions or the sequence builder for similar low-cost implementations for suspend.)

This also works in a suspended way by leveraging a small state-machine to keep track of the internal state, which can be done by simple Int flags. #112

You're correct that the current encoding in 0.10.x and before it is more expensive, but this will be changed with the new encoding. And can later be solved in a generic way with the compiler plugin.

I hope that answers your questions, and what the current state is :)
I'm going to close this issue since it can be tracked in #115 & #116.

Thanks for the feedback! And if you have any questions feel free to ask questions here or on the Kotlin Slack in the #arrow channel ;)

from arrow-core.