[jira] [Assigned] (SPARK-16694) Use for/foreach rather than map for Unit expressions whose side effects are required

["Apache Spark (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/SPARK-16694?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Apache Spark reassigned SPARK-16694:
------------------------------------

    Assignee: Apache Spark  (was: Sean Owen)

> Use for/foreach rather than map for Unit expressions whose side effects are required
> ------------------------------------------------------------------------------------
>
>                 Key: SPARK-16694
>                 URL: https://issues.apache.org/jira/browse/SPARK-16694
>             Project: Spark
>          Issue Type: Improvement
>          Components: Examples, MLlib, Spark Core, SQL, Streaming
>            Reporter: Sean Owen
>            Assignee: Apache Spark
>            Priority: Minor
>
> {{map}} is misused in many places where {{foreach}} is intended. This caused a bug in https://issues.apache.org/jira/browse/SPARK-16664 and might be a latent bug elsewhere; it's also easy to find with IJ inspections. Worth patching up. 
> To illustrate the general problem, {{map}} happens to work in Scala where the collection isn't lazy, but will fail to execute the code when it is. {{map}} also causes a collection of {{Unit}} to be created pointlessly.
> {code}
> scala> val foo = Seq(1,2,3)
> foo: Seq[Int] = List(1, 2, 3)
> scala> foo.map(println)
> 1
> 2
> 3
> res0: Seq[Unit] = List((), (), ())
> scala> foo.view.map(println)
> res1: scala.collection.SeqView[Unit,Seq[_]] = SeqViewM(...)
> scala> foo.view.foreach(println)
> 1
> 2
> 3
> {code}



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