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Apr 10, 2019
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add docs about crossing dask and stream nodes #176

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add docs about crossing dask and stream nodes
CJ-Wright May 10, 2018
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code case b
CJ-Wright May 10, 2018
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changes from @martindurant
CJ-Wright Mar 26, 2019
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20 changes: 20 additions & 0 deletions docs/source/dask.rst
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Expand Up @@ -117,3 +117,23 @@ did.
``source.emit``.

.. _Dask: https://dask.pydata.org/en/latest/


Gotchas
+++++++


An important gotcha with ``DaskStream`` is that it is a subclass ``Stream``, and so can be used as an input
to any function expecting a ``Stream``. If there is no intervening ``.gather()``, then the downstream node will
receive Dask futures instead of the data they represent::

source = Stream()
source2 = Stream()
a = source.scatter().map(inc)
b = source2.combine_latest(a)

In this case, the combine operation will get real values from ``source2``, and Dask futures.
Downstream nodes would be free to operate on the futures, but more likely, the line should be::

b = source2.combine_latest(a.gather())