Hi all, I've written a little blog post about effe...

# arrow

[HieiJ]

Hi all, I've written a little blog post about effect polymorphism with fx: https://www.msec.it/blog/effect-polymorphism-with-arrow-fx/
Since I'm an FP beginner, just experimenting, do you have any comment/correction about this?

[pakoito]

I’ll do some corrections!

[pakoito]

the implementation of attempt in the second snippet is incorrect

[pakoito]

return concurrent { !attempt { f() } }.asSuspended()

[pakoito]

! is only available in fx blocks. I don’t know what concurrent constructor is here

[pakoito]

to make it a bit snappier try

[pakoito]

suspend fun <A> attempt(f: suspend () -> A): Either<Throwable, A>

[pakoito]

override suspend fun <A> attempt(f: suspend () -> A): Either<Throwable, A> = fx { !effect { fx() }.attempt() }.asSuspended()

[pakoito]

okay, next

[pakoito]

env.concurrent { !effect { env.program() } }

is

env.fx { !effect { env.program() } }

[simon.vergauwen]

env.concurrent is actually correct here. Since ConcurrentFx<F> as he extends from his interface is fx. So instead of extending Concurrent<F> and doing fx.concurrent { he’s extending the DSL directly which results in concurrent {

[simon.vergauwen]

Hence also concurrent { !attempt { f() } }.asSuspended()

[simon.vergauwen]

He probably wants to extend Concurrent<F> instead and do override suspend fun <A> attempt(f: suspend () -> A): Either<Throwable, A> = effect(f).attempt().asSuspended().

[simon.vergauwen]

That way env.concurrent { !effect { env.program() } } would also simply become effect { env.program() } without wrapping it in another concurrent { call.

[pakoito]

oooooh I see

[HieiJ]

Thank you, I'll take a look at your suggestions 🙂

[HieiJ]

I've made the changes, here is the updated code: https://gist.github.com/colomboe/66049b48f35ece7421b1331bfa870195

[HieiJ]

But I get a strange warning on the object IOSideEffectHandling definition

[simon.vergauwen]

A warning about multiple inheriting functions from multiple classes

[HieiJ]

exactly

[simon.vergauwen]

Yes, you can simply ignore or suppress it for now. We need to check how we can get that out of users code. It’s a non-issue.

[HieiJ]

So I'll update the blog post soon, thank you for your feedback

[simon.vergauwen]

Happy to see this content being made :) happy to help any time

[raulraja]

@HieiJ feel free to PR to the Arrow blog section!

[raulraja]

https://github.com/arrow-kt/arrow/issues/new?assignees=MaureenElsberry&labels=Media+Resource&template=add-community-resource.md&title=%5BAdd+Media%5D