Attempting to implement code similar to that found in the higher-order-function example from http://www.codecommit.com/blog/scala/scala-for-java-refugees-part-6 val button = new JButton("test") button.addActionListener{ e:ActionEvent => println("test") } add(button) leads to the following error: type mismatch; found : (java.awt.ev...
Idle pondering from a Scala learner perhaps, but ... in my tinkerings I've written the following: ( n.child.size > 0 ) && ( n.child.filter( ! _.isInstanceOf[Text] ).size == 0 ) ('n' is a scala.xml.Node, but that's not important. Nor is the particular logic.) Calling child() twice isn't so good, so I was about to change it: val list...
In Scala (2.7), if I have this function: def foo(args: Array[String]) = for (arg <- args) println(arg) If I now try to define the following: def bar(args: String*) = foo(args) then the compiler complains: <console>:5: error: type mismatch; found : String* required: Array[String] def bar(args: String*) = foo(args) ...
After doing the whole "enterprise" programming for a while, I'm seriously disillusioned by the language itself and always feel quite hampered if I have to go back to it. The project size of your average Android app isn't too intimidating and the libraries are actually quite nice regarding their coding style, but if I could avoid Java, I'...
Hi, I have installed latest scala ide plugin to eclipse (Version: 3.4.2). It seems installation is ok without any errors. I am able to create a scala project and add a package, but i couldn't add scala object, at the time it shows "projectname" is not a Scala project error message in add object dialog. I have googled and found it co...
Hello. I installed Scala IDE for Eclipse, and it seems to be working okay. So now I'm trying to import a Lift project (specifically -- autogenerated Lift project from Stax application platform), and now I'm having four errors at my workspace: value net is not a member of package <root> Boot.scala /rss2lj/src/scala/bootstrap/liftweb lin...
I have a case class case class ~[a,b](_1:a, _2:b) When I want to do pattetn matching new ~("a", 25) match{ case "a" ~ 25 => } I can use it this way because "a" ~ 25 and ~("a", 25) are equivalent. But if I want to match new ~("a", new ~("b", 25)) by {case "a" ~ "b" ~ 25 => } troubles begin. I understand that this statements aren't...
I am a bit confused by this ArithmeticException. I have tried this on Scala 2.8.0.RC6 and RC7. scala> 7.12 to(8, 0.2) res0: scala.collection.immutable.NumericRange[Double] = NumericRange(7.12, 7.32, 7.52, 7.72, 7.92) scala> 7.12 to(8, 0.5) res2: scala.collection.immutable.NumericRange[Double] = NumericRange(7.12, 7.62) scala> 7.12 to...
This doesn't compile with Scala 2.7.7.final or 2.8.0.final for me: new FileInputStream("test.txt") getChannel transferTo( 0, Long.MaxValue, new FileOutputStream("test-copy.txt") getChannel) This does compile with Scala 2.7.7.final and 2.8.0.final for me: new FileInputStream("test.txt") getChannel() transferTo( 0, Long.MaxValu...
Hi, I'm fairly new to Scala, but I'm doing my exercises now. I have a string like "A>Augsburg;B>Berlin". What I want at the end is a map val mymap = Map("A"->"Augsburg", "B"->"Berlin") What I did is: val st = locations.split(";").map(dynamicListExtract _) with the function private def dynamicListExtract(input: String) = { if (inp...
Which tools or libraries do you wish existed in the Scala ecosystem? Are there any existing ones you wish were greatly improved? ...
How do you make a protected method in a class accessible to just all classes in the package in Scala? ...
There are a huge amount of tasks. Each task is belong to a single group. The requirement is each group of tasks should executed serially just like executed in a single thread and the throughput should be maximized in a multi-core (or multi-cpu) environment. Note: there are also a huge amount of groups that is proportional to the number o...
I created a class Foo that has the method toArray() that returns an Array<Int>. Now, I have a HashMap mapping Strings to HashMaps, which map Objects to Foo. That is: HashMap<String,HashMap<Object,Foo>> And I want to create a new object of type: HashMap<String,HashMap<Object,Array<Int>>> That is obtained by calling the function toA...
What I'd like to achieve is having a proper implementation for def dynamix[A, B](a: A): A with B I may know what B is, but don't know what A is (but if B has a self type then I could add some constraints on A). The scala compiler is happy with the above signature, but I could not yet figure out how the implementation would look like -...
There seems to be a lot of enthusiasm among Scala bloggers lately for the type classes pattern, in which a simple class has functionality added to it by an additional class conforming to some trait or pattern. As a vastly oversimplified example, the simple class: case class Wotsit (value: Int) can be adapted to the Foo trait: trait F...
I have an IntelliJ project with eight modules and roughly 500 KLines of Java. I added a Scala Facet to a module that depends on all the other modules. When compiling HelloWorld.scala in IntelliJ IDEA 9.0.2: object HelloWorld { def main(args: Array[String]) { println("Hello World!") } } I got the following output in the Messa...
I downloaded scala 2.8 but when executing scala.bat it says system cannot find set_home I didn't have this problem with old version of scala. So how to launch scala ? Update: I'm on windows 7, I have setup JAVA_HOME environment variable. the problem is the set_home batch command that is not known. I have found the official tutorial ...
I need iterate through a List but circular way. I need too add new elements to the list and iterate over all elements (olds and news elements), How I do it? Is there any data structure for them? ...
I'm trying to make an actor 'go to sleep' waiting for another actors signal. I want to do something like: def act(){ loop{ //Should I use loop here too?? if(sleepy){ react{ //SLEEPING case "Wake Up"=> sleepy=false; //just to breack the react } }else{ ...