Till Rohrmann created FLINK-3557:
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Summary: Scala DataStream fold method should take fold function in
secondary parameter list
Key: FLINK-3557
URL: https://issues.apache.org/jira/browse/FLINK-3557
Project: Flink
Issue Type: Improvement
Components: DataStream API, Scala API
Affects Versions: 1.0.0
Reporter: Till Rohrmann
Assignee: Till Rohrmann
Priority: Minor
The current Scala DataStream API offers a {{fold}} method. The {{fold}} method
takes two parameters, the initial value and the fold function. However, both
parameters are specified in the same parameter list. This makes it clumsy to
provide a multi-line anonymous function as the fold function parameter in
Scala. One would have to wrap the function in an additional pair of curly
braces. This could be avoided by having a second parameter list which takes the
fold function. This would, additionally, be consistent with Scala's collection
API.
Old style
{code}
windowedStream.fold(("R:", 0), { (acc: (String, Int), v: (String, Int)) =>
(acc._1 + v._1, acc._2 + v._2) })
{code}
vs. new style
{code}
windowedStream.fold(("R:", 0)){ (acc: (String, Int), v: (String, Int)) =>
(acc._1 + v._1, acc._2 + v._2) }
{code}
These changes are API breaking.
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