If you have an operation like this ```suspend fun...

# arrow

[Cody Mikol]

If you have an operation like this

suspend fun foo() = either {
  val foo = !getFoo()
  val bar = !getBar()
  val foobar = !foobarFactory.make(foo, bar)
}

are foo and bar evaluated concurrently and then foobar once its dependencies have resolved?

I’m trying to get a better overview of how arrow handles these suspended functions. Currently we are using either.eager , but I’d like to better understand the non-blocking either so I can benefit from that.

[simon.vergauwen]

Hey @Cody Mikol,

They're not evaluated concurrently, the program executes sequentially here just like either.eager does.

The only difference between either.eager and either is that in the latter you can call suspend fun from inside the { } block.

[Cody Mikol]

That makes total sense, thank you 🙂

[simon.vergauwen]

If you want to make them run in parallel you can use Arrow Fx Coroutines inside either { } like so.

suspend fun foo() = either {
  val (foo, bar) = parZip(
    { getFoo().bind() },
    { getBar().bind() })
    { foo, bar -> Pair(foo, bar) }

  val foobar = !foobarFactory.make(foo, bar)
}

[Cody Mikol]

That is exactly what I’m looking for

[Cody Mikol]

Thanks for all your work on arrow, it has totally changed the way I think about writing programs