we need some help…

We want in teaching purposes write small games with two cannons. The main problem now is how to do correct animation with loaded images ?
We want that children draw two cannons and background. Than we scan this pictures, extract background and canons and put in into Kojo scene.
So the problems:
1. every drawn image overlaps the image we want to draw at runtime (example below)
2. we have original canon image that is paralel to X axis, and we want to rotate it in absoulte manner like "rot(13) -> im", but not in reference manner like in example below.
3. how correctly we should draw the scene (possibly using picture stack)
- draw background
- above background should place two cannons
- than print wind/gravity/velocity/other data

import Staging._ import Staging.{animate, wipe} cleari val im = PicShape.image("/home/alex/circle.png") // small picture about 60x60 pixels val ang=1; animate{ wipe im.rotate(ang).realDraw() line(0,0,200,200) }

I notice that the currently released GeoGebra software is already translated into Dutch, but that Dutch translation is not included in Kojo. How can be get the Dutch translation of GeoGebra into Kojo?

I would like to enable Kojo without creating a security hole. Any suggests would be appreciated.

Rushi Shukla said:
I have all pre-requisites for building kojo but after issuing the 'ant build' command , I get the following error :

BUILD FAILED
/home/rushi/netbeans-7.3/harness/suite.xml:184: The following error occurred while executing this line:
/home/rushi/git/kojo/kojo/ScalaEditorLite/build.xml:8: The following error occurred while executing this line:
/home/rushi/git/kojo/kojo/ScalaEditorLite/scala-build.xml:10: You must set SCALA_HOME or environment property and append "-J-Dscala.home=scalahomepath"
property to the end of "netbeans_default_options" in NetBeansInstallationPath/etc/netbeans.conf to point to
Scala installation directory.

Rushi,

Please work with the Kojo2 project - http://code.google.com/p/kojolite/; you seem to be trying out Kojo1

Cheers,
- Lalit

But even then I am getting the below:

Exception in thread "main" java.lang.OutOfMemoryError: Java heap space
[scalac] at java.util.jar.Manifest$FastInputStream.<init>(Manifest.java:313)
[scalac] at java.util.jar.Manifest$FastInputStream.<init>(Manifest.java:308)
[scalac] at java.util.jar.Manifest.read(Manifest.java:176)
[scalac] at java.util.jar.Manifest.<init>(Manifest.java:50)
[scalac] at java.util.jar.JarFile.getManifestFromReference(JarFile.java:167)
[scalac] at java.util.jar.JarFile.getManifest(JarFile.java:148)
[scalac] at sun.misc.URLClassPath$JarLoader$2.getManifest(URLClassPath.java:696)
[scalac] at java.net.URLClassLoader.defineClass(URLClassLoader.java:228)
[scalac] at java.net.URLClassLoader.access$000(URLClassLoader.java:58)
[scalac] at java.net.URLClassLoader$1.run(URLClassLoader.java:197)
[scalac] at java.security.AccessController.doPrivileged(Native Method)
[scalac] at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
[scalac] at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
[scalac] at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
[scalac] at java.lang.ClassLoader.loadClass(ClassLoader.java:247)
[scalac] at scala.tools.nsc.Global.throwableAsString(Global.scala:168)
[scalac] at scala.tools.nsc.Global.logThrowable(Global.scala:165)
[scalac] at scala.tools.nsc.Main$.process(Main.scala:113)
[scalac] at scala.tools.nsc.Main$.main(Main.scala:123)
[scalac] at scala.tools.nsc.Main.main(Main.scala)

Indentation should follow the “2-space convention”. … [some code examples follow]

The Scala language encourages a startling amount of nested scopes and logical blocks (function values and such). Do yourself a favor and don’t penalize yourself syntactically for opening up a new block. Coming from Java, this style does take a bit of getting used to, but it is well worth the effort.

The Script Editor currently seems to apply the 4-space convention: admittedly this is what I'm used to myself and therefore seems perfectly normal to me (e.g. it's in the PEP8 Python style guide and is standard in Java) but there would seem to be some logic in following Scala's style guide. A foolish consistency is the hobgoblin of little minds etc, but Kojo's default layout, with the Script Editor and Output Pane sharing the bottom of the screen, does leave the typing space fairly narrow.

Anyway, thanks you for making Kojo available, it's a great environment for teaching kids how to program. I teach physics (with electronics and computer science stuff) in a French high school in Paris. I've used differents langages and environments (pascal, C, python, smalltalk Squeak,DrRacket scheme) during the 10 last years but I want to switch this year with scala as langage and Kojo as IDE.

From my experience when teaching programming to kids (secondary school, 13-18 years old) you need:

1. a good langage:
- a simple and concise syntax (scheme,smalltalk, python and scala are good)
- algebraic notation like usual math notation (python, scala)
- real functional programming is an advantage since many concepts are already seen in math (scheme, scala, python)
- high level data collections as list, set, dictonary (hash table)(scheme,smalltalk, python, scala)

2. a good environment:
- an interactive Read-Eval-Print Loop (scheme,smalltalk, python, scala)
- friendly debug system, stepping… (DrRacket scheme, Squeak, Greenfoot)

3. Fun: graphics programs, drawings, sprites games (DrRacket, Squeak, Greenfoot, Kojo)

Bonus:
- interactive geometry with integration of geogebra (Kojo, Mathpiper)
- C.A.S. Computer Algebra System (Mathpiper)

Considering both the langage and the environment, Kojo is a great chalenger.
In my point of view, inspiring environments for kojo would be:

DrRacket:
http://racket-lang.org/
http://docs.racket-lang.org/quick/index.html
http://world.cs.brown.edu/
http://www.htdp.org/

Greenfoot:
http://www.greenfoot.org/

Mathpiper: (interactive geometry and computer algebra system in a functional programming langage).
http://www.mathpiper.org/

Xavier Coolen.

Is there any chance of introducing animation of 2D or 3D models with connections, movement, and forces like gravitation and magnetism?

Is it possible to use a more full featured IDE, like Eclipse, with Kojo?

Thanks,
Mushtaq

PS: Thanks for making this amazing tool!

Instructions for building Kojo with Netbeans 7 are available here:
http://code.google.com/p/kojo/source/browse/Build.txt

The older version of Kojo (which ran on the Netbeans 6.8 Platform), now lives on the NB6.8-scala2.8.x branch (http://code.google.com/p/kojo/source/browse/?r=NB6.8-scala2.8.x).

Thanks in advance

Marco

Kojo can definitely benefit from Network Collaboration/Competition/Gaming features. Here are some ideas on things that we might want to see within KojoNet:

• A Code Exchange - to share code/sketches, rate them, and discuss them (under active development)
• A Code Competition area - where users upload their competition entries during a specified competition time-range. These entries are then judged to declare winners (it should be easy to adapt the code exchange technology to implement this).
  • Competitions could be:
    • Programming puzzles,
    • Or Programming games like the one mentioned here some time ago by Peter. I'm not quite sure whether the game that Robert describes (in the link at the beginning of the post) falls in this category.
  • There are privacy and security issues involved with implementing competitions (as mentioned by Robert)

How do these features sound?
One great thing, in my mind, about the above features is that - I can see them getting implemented relatively quickly!

What other features can we think of?

In terms of implementation, here's the technology being used for the current cut of the Code Exchange:

• Scala XML literals for web templating
• The Play Framework (version 1.1)
• JPA/Hibernate
• Postgresql
• A slice on Linode.com for deployment

It should be relatively easy to run this stuff on the App Engine, if we decide to go in that direction.
If there's interest in hacking on this code, I'll set up a repo on Google code. Lemme know?

That's it for now - just a few rambling thoughts before I crash for the night. Feel free to pitch in with ideas…

Ideas:

1) Have a set of tasks to complete! I believe this is a great idea and should be central point of Kojo.

2) Create sharing area. Kojo could have "upload" button that will put example on some website with a screenshot.
Importing examples to Kojo should be easy as well.

2a) To improve 2) some ranking system should be created. [maybe something like StackOverflow.com would work]

3) Kojo should by injected to computer courses in some high schools to find its weakest points as learning platform.
Important: the teacher should be someone unfamiliar with Kojo, but familiar with programming

I don't see anything more important than the above for future of Kojo.

My contributions to Kojo are licensed under the GNU GPL v3 license. The full text of the license is available at http://www.gnu.org/licenses/gpl-3.0.txt

Links:

• code: http://code.google.com/r/peterlewerin-staging/
• reference: http://lewerin.se/peter/kojo/staging.html
• wiki: http://code.google.com/p/kojo/wiki/StagingModule

Original message (which all the replies are about):

Announcement: I've committed a small update that changes and extends the set of random number commands (start small!).

I replaced the randomDouble() command by an overloaded random(), added a randomFrom() command that picks a random member from a sequence, and added a randomSeed() command that sets the generator to a known sequence of numbers.

I've made a slight change to ScalaCodeRunner.scala; in Builtins I changed the declaration of Random and added two methods:

 private val Random = new scala.util.Random import scala.math._ def random[A] (upperBound: A)(implicit n: Numeric[A]): A = { val ub = n.toDouble(upperBound) if (upperBound.isInstanceOf[Int]) (Random.nextInt(ub.toInt)).asInstanceOf[A] else if (upperBound.isInstanceOf[Float]) (Random.nextFloat * ub.toFloat).asInstanceOf[A] else (Random.nextDouble * ub).asInstanceOf[A] } def random[A] (lowerBound: A, upperBound: A)(implicit n: Numeric[A]): A = { val lb = n.toDouble(lowerBound) val ub = n.toDouble(upperBound) - lb val r = lb + random(ub) if (upperBound.isInstanceOf[Int]) r.toInt.asInstanceOf[A] else if (upperBound.isInstanceOf[Float]) r.toFloat.asInstanceOf[A] else r.asInstanceOf[A] }

If I can't get it to work I'll try reverting the change, but it doesn't seem likely that the above should be causing the problems mentioned.

Any ideas?

EDIT: I've reverted to revision 175 of KojoEnv now, and that actually made the reports about Point go away, but NB still can't find RunContext or CodeRunner unless I open core/codeRunner.scala in a window. And nothing I do makes the instance method visible, apparently. Curious.

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