what is the difference between the `block: suspend () -> T` and `block: suspend CoroutineScope.(...

# coroutines

[vineethraj49]

what is the difference between the block: suspend () -> T and block: suspend CoroutineScope.() -> T types?

[octylFractal]

the second one is usually improper, as it passes two contexts down to the function -- the suspend one and the CoroutineScope one -- and it's not clear which one will be used

[octylFractal]

usually you'd stick with either suspend () -> T, indicating that it's a normal suspend function that will actually suspend while doing work, or with CoroutineScope.() -> T, which indicates that it will launch a separate coroutine that won't suspend this codepath. usually T will contain some reference to the Job that was started in this case.

[Evan R.]

The second one could potentially let the suspending function launch coroutines into your current scope. The first one will force block() to use coroutineScope {} to launch its coroutines and therefore all launched coroutines in block() are guaranteed to complete with that signature

[louiscad]

@octylFractal The second one is absolutely NOT improper. That's the signature of launch, async and coroutineScope lambdas. If a custom function creates an inner scope as well, it's totally okay, it's totally to have the lambda(s) have that signature.