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  • scala jpa notifying hibernate

    - by coubeatczech
    Hi, i just tried to play a little with Scala Jpa, Downladed and run the basic lift-jpa-basic maven archetype, it works, but when I try to add my own @Entity, there is Unknown entity exception thrown. So what do I need to tell the environment to notify my entities? Thanks for answering.

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  • Scala compiler says unreachable code, why?

    - by taotree
    I'm new to Scala... Here's the code: def ack2(m: BigInt, n: BigInt): BigInt = { val z = BigInt(0) (m,n) match { case (z,_) => n+1 case (_,z) => ack2(m-1,1) // Compiler says unreachable code on the paren of ack2( case _ => ack2(m-1, ack2(m, n-1)) // Compiler says unreachable code on the paren of ack2( } } I'm trying to understand that... why is it giving that error?

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  • Scala giving me "illegal start of definition"

    - by Malvolio
    I'm trying to get started with Scala and cannot get out of the starting gate. A file consisting of the line package x gives me error: illegal start of definition Regardless of what x is and regardless of where I put the file (I had a theory that I had to place the file in a directory hierarchy to match the package definition, but no). I get the same error with the example code from the web site and with the REPL.

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  • scala currying by nested functions or by multiple parameter lists

    - by Morgan Creighton
    In Scala, I can define a function with two parameter lists. def myAdd(x :Int)(y :Int) = x + y This makes it easy to define a partially applied function. val plusFive = myAdd(5) _ But, I can accomplish something similar by defining and returning a nested function. def myOtherAdd(x :Int) = { def f(y :Int) = x + y f _ } Cosmetically, I've moved the underscore, but this still feels like currying. val otherPlusFive = myOtherAdd(5) What criteria should I use to prefer one approach over the other?

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  • scala for yield setting a value

    - by coubeatczech
    Hi, I want to create a list of GridBagPanel.Constraints. I read it in the scala programming book, that there is a cool for-yield construction, but I probably haven't understood the way it works correctly, because my code doesn't compile. Here it is: val d = for { i <- 0 until 4 j <- 0 until 4 } yield { c = new Constraints c.gridx = j c.gridy = i } I want to generate a List[Constraints] and for every constraint set different x,y values so later, when I later add the components, they're going to be in a grid.

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  • Ant-Ivy-Scala Template: any suggestions on improvements?

    - by luigi-prog
    I just created a template project for Scala using Ant and Apache Ivy. I want to get the communitie's input on any improvements to the Template so it can be improved. The Environment effectively consists of 3 files: build.xml ivy.xml ivysettings.xml running ant init will create all needed directories. I was wondering if there are any Ant or Apache Ivy gurus around that could give some input. The Git Project is Located Here And the Project HomePage here

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  • What is the best scala-like persistence framework available right now?

    - by egervari
    What is the best scala-like persistence framework available right now? Hibernate works, but it's not very scala-like. It insists on using annotations, no-arg constructors, doesn't work with anonymous class instances, doesn't work with scala collections, has an outdated string-based query model, etc. I'm looking for something that really fits Scala. Does it exist? Or do I have to make it?

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  • SBT run differences between scala and java?

    - by Eric Cartner
    I'm trying to follow the log4j2 configuration tutorials in a SBT 0.12.1 project. Here is my build.sbt: name := "Logging Test" version := "0.0" scalaVersion := "2.9.2" libraryDependencies ++= Seq( "org.apache.logging.log4j" % "log4j-api" % "2.0-beta3", "org.apache.logging.log4j" % "log4j-core" % "2.0-beta3" ) When I run the main() defined in src/main/scala/logtest/Foo.scala: package logtest import org.apache.logging.log4j.{Logger, LogManager} object Foo { private val logger = LogManager.getLogger(getClass()) def main(args: Array[String]) { logger.trace("Entering application.") val bar = new Bar() if (!bar.doIt()) logger.error("Didn't do it.") logger.trace("Exiting application.") } } I get the output I was expecting given that src/main/resources/log4j2.xml sets the root logging level to trace: [info] Running logtest.Foo 08:39:55.627 [run-main] TRACE logtest.Foo$ - Entering application. 08:39:55.630 [run-main] TRACE logtest.Bar - entry 08:39:55.630 [run-main] ERROR logtest.Bar - Did it again! 08:39:55.630 [run-main] TRACE logtest.Bar - exit with (false) 08:39:55.630 [run-main] ERROR logtest.Foo$ - Didn't do it. 08:39:55.630 [run-main] TRACE logtest.Foo$ - Exiting application. However, when I run the main() defined in src/main/java/logtest/LoggerTest.java: package logtest; import org.apache.logging.log4j.Logger; import org.apache.logging.log4j.LogManager; public class LoggerTest { private static Logger logger = LogManager.getLogger(LoggerTest.class.getName()); public static void main(String[] args) { logger.trace("Entering application."); Bar bar = new Bar(); if (!bar.doIt()) logger.error("Didn't do it."); logger.trace("Exiting application."); } } I get the output: [info] Running logtest.LoggerTest ERROR StatusLogger Unable to locate a logging implementation, using SimpleLogger ERROR Bar Did it again! ERROR LoggerTest Didn't do it. From what I can tell, ERROR StatusLogger Unable to ... is usually a sign that log4j-core is not on my classpath. The lack of TRACE messages seems to indicate that my log4j2.xml settings aren't on the classpath either. Why should there be any difference in classpath if I'm running Foo.main versus LoggerTest.main? Or is there something else causing this behavior? Update I used SBT Assembly to build a fat jar of this project and specified logtest.LoggerTest to be the main class. Running it from the command line produced correct results: Eric-Cartners-iMac:target ecartner$ java -jar "Logging Test-assembly-0.0.jar" 10:52:23.220 [main] TRACE logtest.LoggerTest - Entering application. 10:52:23.221 [main] TRACE logtest.Bar - entry 10:52:23.221 [main] ERROR logtest.Bar - Did it again! 10:52:23.221 [main] TRACE logtest.Bar - exit with (false) 10:52:23.221 [main] ERROR logtest.LoggerTest - Didn't do it. 10:52:23.221 [main] TRACE logtest.LoggerTest - Exiting application.

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  • Thread pool in scala

    - by ghedas
    I have a project that is actor-based and for one part of it I must use some actors that receive message after that one actor assigns to each request separately and each actor is responsible for doing its message request, so I need something like a thread pool for actors of my project, are there any features in Scala that is useful for my necessity? how can I achieve this goal? tanks a lot for your attention!

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  • scala actor message definition

    - by BenZen
    Do i need to define class for message i want to retrieve on a scala actor? i trying to get this up where am i wrong def act() { loop { react { case Meet = foundMeet = true ; goHome case Feromone(qty) if (foundMeet == true) = sender ! Feromone(qty+1); goHome }}}

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  • Are Maybes a good pattern for scala?

    - by Fred Haslam
    For a while I have been struggling to integrate scala with java methods that might return null. I came up with the following utility which helps a lot: // produce an Option, nulls become None object Maybe { def apply[T](t:T) = if (t==null) None else Some(t) } Maybe(javaClass.getResultCouldBeNull()).map( result => doSomeWork(result) ) I have a few questions about this solution: Is there a better or more standard pattern to use? Am I duplicating something that already exists? Does this functionality have hidden gotchas?

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  • Unpacking tuple types in Scala

    - by jpalecek
    I was just wondering, can I decompose a tuple type into its components' types in Scala? I mean, something like this trait Container { type Element } trait AssociativeContainer extends Container { type Element <: (Unit, Unit) def get(x : Element#First) : Element#Second }

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  • Scala passing type parameters to object

    - by Shahzad Mian
    In Scala v 2.7.7 I have a file with class Something[T] extends Other { } object Something extends OtherConstructor[Something] { } This throws the error: class Something takes type parameters object Something extends OtherConstructor[Something] { However, I can't do this object Something[T] extends OtherConstructor[Something[T]] { } It throws an error: error: ';' expected but '[' found. Is it possible to send type parameters to object? Or should I change and simply use Otherconstructor

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  • scala Slider throws casting exception

    - by coubeatczech
    hello, I create an Slider object: val slider = new Slider{ min = 0 max = 30 labels = Map(0 -> new Label("Nula"),15-> new Label("Pul"),30-> new Label("Max")) paintLabels = true } when I run this, an exception is thrown: scala.swing.Label cannot be cast to java.awt.Component but why? When i browse the docs, the excpected type for labels is a Map[Int,Label].

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  • Scala: Can't catch exception thrown inside a closure

    - by Dmitriy
    Disclaimer: absolute novice in Scala :( I have the following defined: def tryAndReport(body: Unit) : Unit = { try { body } catch { case e: MySpecificException => doSomethingUseful } } I call it like this: tryAndReport{ someCodeThatThrowsMySpecificException() } While the call to someCodeThatThrowsMySpecificException happens just fine, the exception is not being caught in tryAndReport. Why? Thank you!

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  • Where do I find an Open Source project written in Scala?

    - by stacker
    I'm looking for a well documented open source project, written in scala to see best practices etc. At sourceforge.net I found a few projects tagged as scala but they were actually written in java. github seems a bit better: http://groups.google.com/group/scala-melb/web/open-scala-projects Does anyone know such a project which could be recommended for learning?

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  • Can one create Sized Types in Scala?

    - by Jens Schauder
    Is it possible to create types like e.g. String(20) in scala? The aim would be to have compiler checks for things like: a: String(20) b: String(30) a = b; // throws a compiler exception when no implicit conversion is available b= a; // works just fine Note: It doesn't need to be/named String

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  • Improving MVP in Scala

    - by Alexey Romanov
    The classical strongly typed MVP pattern looks like this in Scala: trait IView { } trait Presenter[View <: IView] { // or have it as an abstract type member val view : View } case class View1(...) extends IView { ... } case object Presenter1 extends Presenter[View1] { val view = View1(...) } Now, I wonder if there is any nice way to improve on it which I am missing...

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  • Scala Map conversion

    - by Benjamin Metz
    I'm a Scala newbie I'm afraid: I'm trying to convert a Map to a new Map based on some simple logic: val postVals = Map("test" - "testing1", "test2" - "testing2", "test3" - "testing3") I want to test for value "testing1" and change the value (while creating a new Map) def modMap(postVals: Map[String, String]): Map[String, String] = { postVals foreach {case(k, v) => if(v=="testing1") postVals.update(k, "new value")} }

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