It’s confusing that `Flow.toList()` closes the Flo...

# stdlib

[Marc Knaup]

It’s confusing that Flow.toList() closes the Flow but Stream.toList() doesn’t close the Stream.
Is that inconsistency intentional?

[Dominaezzz]

What do you mean by "closes"? Flows can't be closed.

[Marc Knaup]

I’m not sure how exactly it works or is called, but Flows can free resources upon cancelation or completion, don’t they?
I don’t have to take care of that, e.g. I don’t have to “close” a Flow for reading a file in order to close the file descriptor.
With Stream I’ll have to do that, even after a terminal operation like .toList().

[Dominaezzz]

Ah I think I see what you mean. Once a Flow is collected (e.g. calling toList()) it must be completely collected (or cancelled). With this rule, a Flow can hold on to resources once collection starts and release them upon completion/cancellation.

Streams on the other hand, don't have to be completed after iteration begins, so the close method is used to signal a cancellation (I guess).

Disclaimer: Haven't properly used Streams.

[Marc Knaup]

Yes, Stream must be closed even after a terminal operation has completed.
Hence the confusion when using Kotlin’s toList() on each.

[Dominaezzz]

OH! You are referring to Kotlin's toList() , I thought it was a special java function.
Can you point me to the toList() function? I don't think it's the same function for both objects.

[Marc Knaup]

It’s not the same function. It’s just very similar.
In both cases you have a stream of value and in one case Kotlin’s toList() will close resources, in the other case it won’t.

I think it’s a problem with Streams, but because they’re so similar and both coming from Kotlin, it’s still confusing.