I have been looking at type inference in Scala and there are a couple of things I'd like to understand a bit better around why expression/method-return types have to be explicitly declared in a few cases. Explicit return declaration Example (works if return keyword is ommitted): def upCase(s: String) = { if (s.length == 0) retur...
I'd like to convert a piece of Java code which looks like the following into Scala: for (Iterator<Task> it = tasks.iterator(); it.hasNext() && workflow.isAutoRun();) { Task task = it.next(); if (!runTask(task)) break; } I am not a fan of the scala for-comprehensions (not that I know how to break the iteration anyway) and I've ...
I'm playing with scala's distributed actors. Very nice. I have a server which executes incoming function objects. For example, the client has object Tasks { def foo = {Console.println("I am Foo")}; def bar = {Console.println("I am Bar");} } // In client actor... ... server ! Tasks.foo _ ... And the server can pick these up an...
I have the data for my webapp in a database that is accessed differently from different places. There is no generic code that can just do it for both. So I want to know at run time which env I am in. In fact, the code to run really depends on whether it is run within or without tomcat, so I would like to detect this at runtime. How d...
Hi, I was browsing scala tests and I don't understand why the compiler produces a warning when you compare "two fresh objects". This is the test' outputs: http://lampsvn.epfl.ch/trac/scala/browser/scala/trunk/test/files/neg/checksensible.check Example: checksensible.scala:12: warning: comparing a fresh object using `!=' will always ...
How in Scala to find unique items in List? ...
I'm trying to modify the boot.scala in lift and running into a funny error. This is what I currently have: val entries = Menu(Loc("Home", List("index"), "Home")) :: Menu(Loc("StudentLogin", List("studentlogin"), "Student Login")) :: Menu(Loc("ProviderLogin", List("providerlogin"), "Provider Login")) LiftRules.setSiteMap(...
I'm using Scala's remote actors, but round-trip time (even of a trivial message) is 80ms, presumably due to underlying socket not having the TCP/IP Nagle algorithm disabled (also known as TCP_NODELAY), or at least that's what someone with some experience with Java RMI informs me. All I'm doing in the client to get a link to the remote a...
Hi all- I have this snippet: class WelcomeSnippet{ def list (xhtml : NodeSeq) : NodeSeq = { object sessionUserType extends SessionVar[String](null) Helpers.bind("entry", xhtml, "edit" -> SHtml.link("/provider",() => sessionUserType("provider"), Text("Edit"))) } } I think its ok, but I keep getting this: Not found:...
Why, in Scala, given: a = List(1, 2, 3, 4) def f(x : String) = { x } does a.map(_.toString) work, but a.map(f(_.toString)) give the error missing parameter type for expanded function ((x$1) => x$1.toString) ...
While working with a Java class in Scala, I noticed that Scala can't multiply Java Doubles. Here's an example: scala> val x:java.lang.Double = new java.lang.Double(34.0) x: java.lang.Double = 34.0 scala> val y:java.lang.Double = new java.lang.Double(2.1) y: java.lang.Double = 2.1 scala> x*y <console>:7: error: value * is not a member...
Hi all- I am trying to store a session variable and then use it to modify the menu in Boot.scala. Here is how I am storing the variable in a snippet: object sessionUserType extends SessionVar[String](null) def list (xhtml : NodeSeq) : NodeSeq = { Helpers.bind("sendTo", xhtml, "provider" -> SHtml.link("/provid...
Unlike Java, Scala lets you do a bare "try", without either a catch or finally clause: scala> try { println("Foo") } Foo Does this actually have any meaning beyond, { println("Foo") } ? ...
Hi all- I feel like I'm monopolizing the stack for Scala/Lift, so I apologize, but the questions keep coming. Here's the latest. I'm trying to restrict access to anything in the /login/* to those users who have not yet logged in. Here is how I'm trying to do it: val entries = Menu(Loc("Home", List("index"), "Home")) :: //login stuff...
Hi, I feel a bit insecure about using actors in Scala. I have read documentation about how to do stuff..but I guess I would also need some DON'T rules in order to feel free to use them. I think I am afraid that I will use them in a wrong way and I will not even notice it. Can you think of something, that, if applied, would result in ...
Is it possible to inject a persistence context into a scala actor every time it acts? I have a dual Java/Scala spring application, and I am using spring annotations to markup my Java services and methods as transactional. I'd like to use similar functionality within my scala actors. That is, the actor should operate within a single tr...
I'm learning more about Scala and I'm having a little trouble understanding the example of anonymous functions here http://www.scala-lang.org/node/135. I've copied the entire code block below: object CurryTest extends Application { def filter(xs: List[Int], p: Int => Boolean): List[Int] = if (xs.isEmpty) xs else if (p(xs.head)...
Can a scala program be running on a browser with disabled java plugin (as scala is compiled to a jvm bytecode)? In other words: is the jvm disabled provided the java browser plugin is disabled? Or does Scala run server-side and I am confused? ...
This code class Foo(str: String) { val len = str.length def getLen = len def getStr = str} will be compiled to public class Foo implements ScalaObject { private final int len; private final String str; public Foo(String str) { this.str = str; super(); len = str.length(); } ...
I'm using Java's java.util.date class in Scala and want to compare a date object and the current time. I know I can calculate the delta by using getTime(): (new java.util.Date()).getTime() - oldDate.getTime() However, this just leaves me with a Long representing milliseconds. Is there any simpler, nicer way to get a time delta? ...