What is the Scala identifier "implicitly"?
I have seen a function named implicitly used in Scala examples. What is it, and how is it used? Example here: scala> sealed trait Foo[T] { def apply(list : List[T]) : Unit }; object Foo { | implicit def stringImpl = new Foo[String] { | def apply(list : List[String]) = println("String") | } | implicit def intImpl = new Foo[Int] { | def apply(list : List[Int]) = println("Int") | } | } ; def foo[A :
How to wait for several Futures?
You could use a for-comprehension as follows instead: val fut1 = Future{...} val fut2 = Future{...} val fut3 = Future{...} val aggFut = for{ f1Result <- fut1 f2Result <- fut2 f3Result <- fut3 } yield (f1Result, f2Result, f3Result) In this example, futures 1, 2 and 3 are kicked off in parallel. Then, in the for comprehension, we wait until the results 1 and then 2 and then 3 are available. If eithe
how to make saveAsTextFile NOT split output into multiple file?
When using Scala in Spark, whenever I dump the results out using saveAsTextFile, it seems to split the output into multiple parts. I'm just passing a parameter(path) to it. val year = sc.textFile("apat63_99.txt").map(_.split(",")(1)).flatMap(_.split(",")).map((_,1)).reduceByKey((_+_)).map(_.swap) year.saveAsTextFile("year") Does the number of outputs correspond to the number of reducers it uses? D
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