scala

问题 In Scala, I need to create a product type & that represents a compound value, e.g.: val and: String & Int & User & ... = ??? I.e. and should have a String part and an Int part and a User parts inside. This is similar to Scala with keyword: val and: String with Int with User with ... = ??? Having such product type I need a way to, having a function A => A , apply it to some product value and get that product back with A part altered. It implies that each type in product must be unique - that's

问题 In Scala, I need to create a product type & that represents a compound value, e.g.: val and: String & Int & User & ... = ??? I.e. and should have a String part and an Int part and a User parts inside. This is similar to Scala with keyword: val and: String with Int with User with ... = ??? Having such product type I need a way to, having a function A => A , apply it to some product value and get that product back with A part altered. It implies that each type in product must be unique - that's

问题 I'm new to Spark & Scala and I got exception after calling saveAsTextFile(). Hope someone can help... Here is my input.txt: Hello World, I'm a programmer Hello World, I'm a programmer This is the info after running "spark-shell" on CMD: C:\Users\Nhan Tran>spark-shell Setting default log level to "WARN". To adjust logging level use sc.setLogLevel(newLevel). For SparkR, use setLogLevel(newLevel). Spark context Web UI available at http://DLap:4040 Spark context available as 'sc' (master = local[

问题 I'm new to Spark & Scala and I got exception after calling saveAsTextFile(). Hope someone can help... Here is my input.txt: Hello World, I'm a programmer Hello World, I'm a programmer This is the info after running "spark-shell" on CMD: C:\Users\Nhan Tran>spark-shell Setting default log level to "WARN". To adjust logging level use sc.setLogLevel(newLevel). For SparkR, use setLogLevel(newLevel). Spark context Web UI available at http://DLap:4040 Spark context available as 'sc' (master = local[

问题 Apologies if this is a duplicate - I did a few searches and didn't quite find what I need. We have a performance critical piece of our application that converts a Play 2.0 Enumerator (can be thought of as a Stream ) of incoming data to a List (or similar). We will use the fold method on Enumerator and the question is what will be the most performant way to do it. (I will use Stream instead of Enumerator in the code, but the idea should be the same.) val incoming: Stream[Int] = ??? val result:

问题 Apologies if this is a duplicate - I did a few searches and didn't quite find what I need. We have a performance critical piece of our application that converts a Play 2.0 Enumerator (can be thought of as a Stream ) of incoming data to a List (or similar). We will use the fold method on Enumerator and the question is what will be the most performant way to do it. (I will use Stream instead of Enumerator in the code, but the idea should be the same.) val incoming: Stream[Int] = ??? val result:

问题 I'm new to Spark & Scala and I got exception after calling saveAsTextFile(). Hope someone can help... Here is my input.txt: Hello World, I'm a programmer Hello World, I'm a programmer This is the info after running "spark-shell" on CMD: C:\Users\Nhan Tran>spark-shell Setting default log level to "WARN". To adjust logging level use sc.setLogLevel(newLevel). For SparkR, use setLogLevel(newLevel). Spark context Web UI available at http://DLap:4040 Spark context available as 'sc' (master = local[

问题 I have a class which extends org.scalatest.junit.JUnitSuite. This class has a couple of tests. I do not want these tests to run in parallel. I know how simple it is with Specs2 (extend the class with Specification and add a single line sequential inside the class) as shown here: How to run specifications sequentially. I do not want to alter the Build file by setting: parallelExecution in Test := false nor I want to use tags to run specific test files sequentially. All I want is a way to make

问题 I have a class which extends org.scalatest.junit.JUnitSuite. This class has a couple of tests. I do not want these tests to run in parallel. I know how simple it is with Specs2 (extend the class with Specification and add a single line sequential inside the class) as shown here: How to run specifications sequentially. I do not want to alter the Build file by setting: parallelExecution in Test := false nor I want to use tags to run specific test files sequentially. All I want is a way to make

问题 I'm writing a type-safe code and want to replace apply() generated for case class es with my own implementation. Here it is: import shapeless._ sealed trait Data case object Remote extends Data case object Local extends Data case class SomeClass(){ type T <: Data } object SomeClass { type Aux[TT] = SomeClass { type T = TT } def apply[TT <: Data](implicit ev: TT =:!= Data): SomeClass.Aux[TT] = new SomeClass() {type T = TT} } val t: SomeClass = SomeClass() // <------------------ still compiles,