[inglor]

An observable is not the same as a Smalltalk stream, directionality wise. Smalltalk streams are like unix streams or a C stream.

[mpweiher]

Whether the flow is push or pull is a fairly irrelevant implementation detail for a dataflow system.

That doesn't mean it can't have big effects, but if you're relying on those, or they do become relevant, you should probably ask yourself whether your system is really dataflow.