This will work without access to `scala-compiler.jar`:

    Welcome to Scala version 2.9.1.final (Java HotSpot(TM) 64-Bit Server VM, Java 1.6.0_26).
    Type in expressions to have them evaluated.
    Type :help for more information.

    scala&gt; util.Properties.versionString
    res0: java.lang.String = version 2.9.1.final

There are three ways to get the Scala version -

    scala&gt; util.Properties.versionNumberString
    res103: String = 2.11.4

    scala&gt; util.Properties.versionString
    res104: String = version 2.11.4

    scala&gt; util.Properties.versionMsg
    res105: String = Scala library version 2.11.4 -- Copyright 2002-2013, LAMP/EPFL

You can get the Scala version like this:

    scala&gt; scala.tools.nsc.Properties.versionString
    res7: java.lang.String = version 2.9.0.final


I don&#39;t know the specifics of the plugin, though.

We can also get installed Scala version

 1. Open command prompt 
 2. type Scala
 3. You will get following output:

Welcome to Scala version 2.10.3 (Java HotSpot(TM) 64-Bit Server VM, Java 1.8.0_6
0).
Type in expressions to have them evaluated.
Type :help for more information.



I&#39;m trying to generate a linear regression on a scatter plot I have generated, however my data is in list format, and all of the examples I can find of using `polyfit` require using `arange`. `arange` doesn&#39;t accept lists though. I have searched high and low about how to convert a list to an array and nothing seems clear. Am I missing something?

Following on, how best can I use my list of integers as inputs to the `polyfit`?

Here is the polyfit example I am following:
    
    import numpy as np
    import matplotlib.pyplot as plt

    x = np.arange(data)
    y = np.arange(data)

    m, b = np.polyfit(x, y, 1)

    plt.plot(x, y, &#39;yo&#39;, x, m*x+b, &#39;--k&#39;)
    plt.show()

Linear regression with matplotlib / numpy

What is the good way to add file extension &quot;.jpg&quot; to extension-less files with bash?

Add file extension to files with bash

This is not about command-line compiler options. How do I programmatically obtain the Scala version inside code?

Alternatively, where does the Eclipse Scala plugin v2 store the path to `scalac`?


How do I get the Scala version from within Scala itself?

<p>This is not about command-line compiler options. How do I programmatically obtain the Scala version inside code?</p>
<p>Alternatively, where does the Eclipse Scala plugin v2 store the path to <code>scalac</code>?</p>


So Scala is supposed to be as fast as Java. I&#39;m revisiting some [Project Euler][1] problems in Scala that I originally tackled in Java. Specifically Problem 5: &quot;What is the smallest positive number that is evenly divisible by all of the numbers from 1 to 20?&quot;

Here&#39;s my Java solution, which takes 0.7 seconds to complete on my machine:

    public class P005_evenly_divisible implements Runnable{
        final int t = 20;

        public void run() {
            int i = 10;
            while(!isEvenlyDivisible(i, t)){
                i += 2;
            }
            System.out.println(i);
        }

        boolean isEvenlyDivisible(int a, int b){
            for (int i = 2; i &lt;= b; i++) {
                if (a % i != 0) 
                    return false;
            }
            return true;
        }

        public static void main(String[] args) {
            new P005_evenly_divisible().run();
        }
    }

Here&#39;s my &quot;direct translation&quot; into Scala, which takes 103 seconds (147 times longer!)

    object P005_JavaStyle {
        val t:Int = 20;
        def run {
            var i = 10
            while(!isEvenlyDivisible(i,t))
                i += 2
            println(i)
        }
        def isEvenlyDivisible(a:Int, b:Int):Boolean = {
            for (i &lt;- 2 to b)
                if (a % i != 0)
                    return false
            return true
        }
        def main(args : Array[String]) {
            run
        }
    }

Finally here&#39;s my attempt at functional programming, which takes 39 seconds (55 times longer)

    object P005 extends App{
        def isDivis(x:Int) = (1 to 20) forall {x % _ == 0}
        def find(n:Int):Int = if (isDivis(n)) n else find (n+2)
        println (find (2))
    }

Using Scala 2.9.0.1 on Windows&amp;nbsp;7 64-bit. How do I improve performance? Am I doing something wrong? Or is Java just a lot faster?

  [1]: http://en.wikipedia.org/wiki/Project_Euler


How to optimize for-comprehensions and loops in Scala?

I am currently trying to get started with Akka and I am facing a weird problem. I&#39;ve got the following code for my Actor:

    class AkkaWorkerFT extends Actor {
      def receive = {
        case Work(n, c) if n &lt; 0 =&gt; throw new Exception(&quot;Negative number&quot;)
        case Work(n, c) =&gt; self reply n.isProbablePrime(c);
      }
    }

And this is how I start my workers:

    val workers = Vector.fill(nrOfWorkers)(actorOf[AkkaWorkerFT].start());
    val router = Routing.loadBalancerActor(SmallestMailboxFirstIterator(workers)).start()

And this is how I shut everything down:

    futures.foreach( _.await )
    router ! Broadcast(PoisonPill)
    router ! PoisonPill

Now what happens is if I send the workers messages with n &gt; 0 (no exception is thrown), everything works fine and the application shuts down properly. However, as soon as I send it a single message which results in an exception, the application does not terminate because there is still an actor running, but I can&#39;t figure out where it comes from.

In case it helps, this is the stack of the thread in question:

      Thread [akka:event-driven:dispatcher:event:handler-6] (Suspended)	
    	Unsafe.park(boolean, long) line: not available [native method]	
    	LockSupport.park(Object) line: 158	
    	AbstractQueuedSynchronizer$ConditionObject.await() line: 1987	
    	LinkedBlockingQueue&lt;E&gt;.take() line: 399	
    	ThreadPoolExecutor.getTask() line: 947	
    	ThreadPoolExecutor$Worker.run() line: 907	
    	MonitorableThread(Thread).run() line: 680	
    	MonitorableThread.run() line: 182	

PS: The thread which is not terminating isn&#39;t any of the worker threads, because I&#39;ve added a postStop callback, every one of them stops properly.

PPS: `Actors.registry.shutdownAll` workarounds the problem, but I think shutdownAll should only be used as a last resort, shouldn&#39;t it?

Akka Actor not terminating if an exception is thrown

&gt; **Possible Duplicate:**  
&gt; [Tuple parameter declaration and assignment oddity](https://stackoverflow.com/questions/1624484/tuple-parameter-declaration-and-assignment-oddity)  

&lt;!-- End of automatically inserted text --&gt;

In Scala, one can do multiple-variable assignment to tuples via:

    val (a, b) = (1, 2)
    
But a similar syntax for assignment to variables doesn&#39;t appear to work. For example I&#39;d like to do this:

    var (c, d) = (3, 4)
    (c, d) = (5, 6)

I&#39;d like to reuse `c` and `d` in multiple-variable assignment. Is this possible?


Is it possible to have tuple assignment to variables in Scala?

I am trying to create a generic method for object updates using scala / java but I can&#39;t get the class for a type parameter.

Here is my code:

    object WorkUnitController extends Controller {     
     def updateObject[T](toUpdate: T, body: JsonObject){
      val source = gson.fromJson(body, classOf[T]);
      ...
     }
    }

The error i get is 

&gt; class type required but T found

I know in java you can&#39;t do it but is this possible in scala at all?

Thanks!


Scala classOf for type parameter

You can find the following on the web:

1. **Higher kinded type == type constructor?**

 &gt;&lt;!-- language: lang-scala --&gt;
 &gt;
 &gt;     class AClass[T]{...} // For example, class List[T]

 Some say this is a higher kinded type, because it
 abstracts over types which would be compliant with the definition.

 &gt; *Higher kinded types* are types which take other types and construct a new type

 These though are also known as *type constructor*. (For example, in [Programming in Scala][1]).

2. **Higher kinded type == type constructor which takes type constructor as a type parameter?**

 In the paper [Generics of a Higher Kind][2], you can read

 &gt; ... types that abstract over types that abstract over types
 &gt; (&#39;higher-kinded types&#39;) ...&quot;

 which suggests that

 &gt;&lt;!-- language: lang-scala --&gt;
 &gt;
 &gt;     class XClass[M[T]]{...} // or
 &gt;
 &gt;     trait YTrait[N[_]]{...} // e.g. trait Functor[F[_]]

 is a higher kinded type.

So with this in mind, it is difficult to distinguish between *type constructor*, *higher kinded type* and *type constructor which takes type constructors as type parameter*, therefore the question above.

 [1]: http://www.artima.com/pins1ed/type-parameterization.html#19.3
 [2]: http://adriaanm.github.com/files/higher.pdf

What is a higher kinded type in Scala?

I would like to manually check if there are new updates for my app while the user is in it, and prompt him to download the new version. Can I do this by checking the version of my app in the app store - programatically?



Check if my app has a new version on AppStore

is there a way to auto-increment the version code each time you build an Android application in Eclipse?

According to [http://developer.android.com/guide/publishing/versioning.html][1], you have to manually increment your version code in `AndroidManifest.xml`.

I understand, you have to run a script before each build which would, e.g. parse AndroidManifest.xml file, find the version number, increment it and save the file before the build itself starts. However, i couldn&#39;t find out how and if Eclipse supports runnings scripts before/after builds.

I have found [this article][2] about configuring ant builder, but this is not exactly about Android and I fear this will mess up too much the predefined building steps for Android?

Should be a common problem, how did you solve it?

Well, one can do this manually, but as soon as you forget to do this chore, you get different versions with the same number and the whole versioning makes little sense.


  [1]: http://developer.android.com/guide/publishing/versioning.html
  [2]: http://www.ibm.com/developerworks/opensource/tutorials/os-eclipse-tools/section2.html

Auto increment version code in Android app

**SITUATION:**

I have a python library, which is controlled by git, and bundled with distutils/setuptools. And I want to automatically generate version number based on git tags, both for `setup.py sdist` and alike commands, and for the library itself.

For the first task I can use `git describe` or alike solutions (see  https://stackoverflow.com/questions/2058802/how-can-i-get-the-version-defined-in-setup-py-setuptools-in-my-package).

And when, for example, I am in a tag &#39;0.1&#39; and call for &#39;setup.py sdist&#39;, I get &#39;mylib-0.1.tar.gz&#39;; or &#39;mylib-0.1-3-abcd.tar.gz&#39; if I altered the code after tagging. This is fine.

**THE PROBLEM IS:**

The problem comes when I want to have this version number available for the library itself, so it could send it in User-Agent HTTP header as &#39;mylib/0.1-3-adcd&#39;.

If I add `setup.py version` command as in https://stackoverflow.com/questions/2058802/how-can-i-get-the-version-defined-in-setup-py-setuptools-in-my-package, then this version.py is generated AFTER the tag is made, since it uses the tag as a value. But in this case I need to make one more commit after the version tag is made to make the code consistent. Which, in turns, requires a new tag for further bundling.

**THE QUESTION IS:**

How to break this circle of dependencies (generate-commit-tag-generate-commit-tag-...)?


Automatic version number both in setup.py (setuptools) AND source code?

Apple&#39;s doc could have been more clear on how to submit an update version.

As asked in the title,
What&#39;s the difference between

1. version number in itunes connect(which you have to supply when you submit an update)
2. bundle version in xcode
3. bundle versions string, short

Are they related in any way?  

 

What&#39;s the difference between &quot;version number&quot; in iTunes Connect, &quot;bundle version&quot;, &quot;bundle version string&quot; in Xcode?

How can I check whether Java is available (in the PATH or via JAVA_HOME) from a bash script and make sure the version is at least 1.5?

Content Type	Original Author	Original Content on Stackoverflow
Question	mlvljr	View Question on Stackoverflow
Solution 1 - Scala	Paul Butcher	View Answer on Stackoverflow
Solution 2 - Scala	Naga Vijayapuram	View Answer on Stackoverflow
Solution 3 - Scala	HairyFotr	View Answer on Stackoverflow
Solution 4 - Scala	Chinya	View Answer on Stackoverflow

How do I get the Scala version from within Scala itself?

Scala Problem Overview

Scala Solutions

Solution 1 - Scala

Solution 2 - Scala

Solution 3 - Scala

Solution 4 - Scala

Add file extension to files with bash

Linear regression with matplotlib / numpy

Attributions