Don't buffer stream inside of toString()

[lukaseder]

Seq currently buffers any stream when calling toString() because this allows for a nice display in debuggers without wasting the stream / modifying program behaviour.

However, buffering the stream has side effects, mainly also when debugging, breakpoints inside of a stream's lambda transformations might no longer be triggered because the stream is evaluated / consumed on toString(), no longer in the real code. See:
https://youtrack.jetbrains.com/issue/IDEA-160867

[tcn]

Streams are aimed to large(r) data sets (i.e. toString() is pointless anyways) and on purpose composable and lazily evaluated. Consider debugging through this:

final Seq<Integer> cache1 = Seq.of(1, 2, 3);    // and a whole lot more
final Seq<Integer> cache2 = cache1.filter(whatever);    
final Optional<Integer> r = cache2.sum();   // *this* is expected to land on the heap

And the current toString() doesn't even comma-separate the values :)

[lukaseder]

@tcn: Personally, I don't buy the "large(r)" data set argument. Most people will use streams as glorified collections, i.e. stuff with 1000 elements in it, where the stream source is in memory already.

Anyway, I see your point :)

[tcn]

That's why Seq.parallel() returns this, I suppose :)

[lukaseder]

No, why? Seq.parallel() returns this, because it makes no sense to have a parallel sequential stream

[tcn]

https://blog.jetbrains.com/idea/2016/09/intellij-idea-2016-3-eap-helps-migrate-to-java-8s-stream-apis/ ok, you were probably right :)

[lukaseder]

Wow, that's impressive. But what do you mean by "I was right"? With what?

[tcn]

Uhm, well, that "most" people will use Stream/Seq as "glorified collections"; now that IntelliJ has this particular feature.

[lukaseder]

Aha, I thought it was referring to the parallel() comment. Yes indeed, that's the assumption here. In fact, that's the whole reason for being of this library. People wanted cooler collections (as in Scala). Not infinite parallel Streams. Only Brian Goetz wanted that, and 1-2 of his peers ;) (Scala has those features too, but hardly anyone uses them)

[tcn]

Hardly anyone uses DB cursors.