2) coming from rxjava `Observable.just(1).startW...

# coroutines

[ursus]

2)

coming from rxjava

Observable.just(1).startWith(0) emits 0,1

flow

flowOf(1).onStart { emit(0) } emits 1,0

is this by design? a rx fix? pretty foot gunny when mkgrating

also, what if the actual flow is replayed? if its "below" the onStart, id assume it emits first which is not good

[gildor]

They do different things, so it's expected

[gildor]

onStart is closer to onSubscribe from rxjava

[gildor]

There is no startWith in Flow as I know, but it's easy to write such operator using transform

[jw]

Not sure you'd even need transform. Just emit and then emitAll wrapping an upstream flow

[gildor]

Yeah, right,. even easier

[ursus]

Okay thats news, .. is there some flow cheat sheet for rx people?

[ursus]

hmm https://kotlin.github.io/kotlinx.coroutines/kotlinx-coroutines-core/kotlinx.coroutines.flow/on-start.html

flowOf("a", "b", "c")
    .onStart { emit("Begin") }
    .collect { println(it) } // prints Begin, a, b, c

I must be doing something wrong then

[ursus]

Oookay it works as expected, turns out I got punked by .asFlow() 😞

repository.foo()
            .asFlow()
            .map<Foo, Signal<Foo>> { Success(it) }
            .catch { emit(Fail(it)) }
            .onStart { emit(Loading) }
            .collect {
                Log.d("Default", "foo=$it")
                setState { copy(fooSignal = it) }
            }

2020-10-24 19:30:06.870 30453-30501/sk.foo.flowplayground D/Default: foo=sk.foo.flowplayground.Loading@f0b3a3c
2020-10-24 19:30:06.872 30453-30501/sk.foo.flowplayground D/Default: foo=Success(value=Foo(foo=1))
2020-10-24 19:30:06.872 30453-30501/sk.foo.flowplayground D/Default: foo=Success(value=Foo(foo=1))

nevermind

[ursus]

so how do I turn a suspend function into a flow 😄

[florent]

I did flow { emit(repository.foo()) } but not sure that's the way to do it

[ursus]

yes that