you can call `map` and instead of returning a valu...

# arrow

[pakoito]

you can call map and instead of returning a value, do a side-effect that returns `Unit`inside. It’s not a good pattern but that fits every use case for ifRight

[dephinera]

Yes, I figured that out, however it's not that explicit. Also if the last line in the lambda is a statement and not an expression, then I have to explicitly use Unit

[dephinera]

Also - please use threads

[pakoito]

I thought statements returned Unit in Kotlin, I may be wrong

[pakoito]

but yes, if you’re doing a side-effect then the type you’re using is Unit

[pakoito]

if you want to be explicit you can always alias

[pakoito]

inline fun <E,A> Either<E, A>.sideEffectIfRight(f: (A) -> Unit): Either<E, Unit> = map(f)

[Satyam Agarwal]

Shouldn’t flatmap be used if there is side effect to be done on the right hand side ?

[pakoito]

at that point I’d just make the whole snippet suspended, yes

[pakoito]

the new APIs for fx are made for this

[pakoito]

either {
  someEither.bind()
  suspendSideEffect()
}

I believe that works on 0.11

[pakoito]

I don’t know whether it’s there now or will be for the 1.0 rewrite

[pakoito]

@simon.vergauwen or @aballano may know better

[pakoito]

either way, if you’re in suspend Either.catch can help

[Satyam Agarwal]

Yes. But think with suspendSideEffect() we would need to use .bind() as well right ? Else it wouldn’t execute ? Or basically coroutines result will not be returned, and we wouldn’t know if this instruction is executed or not.

[Satyam Agarwal]

I always wrap apis that can throw in Either.catch

[pakoito]

in the new either blocks you can call suspend functions and they’re caught IIRC

[pakoito]

but yes, in any case Either.catch + bind would work

[Satyam Agarwal]

Cool. Thanks.

[dephinera]

Okay, my bad. Statements are evaluated to Unit

[dephinera]

I guess I confused it with a previous version

[Marius Kotsbak]

Why not add something like .foreach() that is used in Scala for blocking side effect without return value.

[pakoito]

Because we don’t want to encourage blocking side-effects. You can always do them in any other block like map, traverse or effectMap even.

[pakoito]

the advice is to wrap them on pure APIs like suspend functions

[Marius Kotsbak]

But sometimes, it is the only thing available, e.g. with GCP client.

[pakoito]

put them into an IO then

[pakoito]

at least it captures exceptions

[Marius Kotsbak]

It is possible to wrap in suspend function yes. Isn't IO deprecated?

[pakoito]

myList.traverse { IO { client.call(it) } }

[pakoito]

IO, or suspend

[pakoito]

depends on what you need