Let me know if that works.

I added some libs to my local kojo env. Perfect.

But the log information coming from those libs is ignored or at least I'm not able to find.

Can someone guide me to how I can get that working?

Cheers, Volker.

If you put P6 below P5 then, the 2nd angle is not properly defined

Good catch. I have added the following to the Story text on that page:
Make sure you keep the point P6 above the top line, and the point P5 below the bottom line, as you move the points around.

The Kojo Overview story asks "What is the length of the square that you just made?"

That question is meant to be:
"What is the length of the side of the square that you just made?"

I have fixed the wording in Kojo. The next version will ask the right question.

PS: I'm loving Kojo

I'm happy to hear that!

If you put P6 below P5 then, the 2nd angle is not properly defined (it goes from the lower parallel until it crosses p5-p6 for a second time (maybe because it is calculated in the wrong sense -> vs <- ?).

Clearly the length is 400, but the system expects the length of the side (? 100) !

(PS: I'm loving Kojo)

The full scala mode is always on!

That's what I like to hear! :)

I was assuming it was offering different language levels/packs like Dr Scheme, glad it's not, I never liked those!

Thanks for your help.

STeve

Is there some way of entering this "full sala" mode without opening the Scala Tuturial?

The full scala mode is always on!

What you're seeing is the fact that - for single lines of code, Kojo works in verbose mode, whareas for multiple lines of code, Kojo works in non-verbose mode. In verbose mode, all output from the Scala interpreter is shown within the Output pane. In non-verbose mode, interpreter output is suppressed.

So, how is one supposed to work with this behavior (for multiple lines of code)? You have two options:

(1) println everything you want to see in the output pane. E.g. :

 def minmax(x: Int, y: Int): (Int,Int) = { if (x > y) (y,x) else (x,y) } print(minmax(1,3)) 

(2) run the showVerboseOutput() command to explicitly force verbose output for multi-line scripts (this is what the Scala Tutorial does).

Cheers,
- Lalit

If I enter:

 def minmax(x: Int, y: Int): (Int,Int) = { if (x > y) (y,x) else (x,y) } 

Single line functions don't seem to trigger this behavior. Also it doesn't happen if I've just opened the Scala Tutorial story and cleared the editor.

Is there some way of entering this "full sala" mode without opening the Scala Tuturial?

Thanks and I greatly enjoy this tool BTW!

Steve Harris and son

• Right-click within the Script Editor to bring up the context (popup) menu
• Go to Experimental Features -> Advanced Options
• Click on the Fonts and Colors button at the top of the Options Dialog
• Within the Syntax tab, select the Default Category
• Change the default font
• Click Ok to close the Options dialog

Note - do not use the escape key to get out of the Options Dialog (if you do, the dialog will not come up again within that run of Kojo!). Instead, use the Ok or Cancel buttons to close the dialog.

Best of luck for the presentation!

Cheers,
- Lalit

Thanks,

Craig.

In the meanwhile I will experiment using Ucigame lib in an other window.

Great.

If you clone the kojo repo and start pushing your enhancements back into your clone, I can see what you're upto and maybe help…
Some related info here:
http://code.google.com/p/kojo/source/browse/Build.txt

Thanks for all the pointers.

I want to switch this year with scala as langage and Kojo as IDE.

That is great to hear! Let me know if you need any help with this…

I would really enjoy an good API sprites games in Kojo.

I think we have two options here:
- extend the Staging API to enable the creation of games. Most of the elements are already in there. The one big thing that is missing is collision detection.
- have another window for games (using a games library like Ucigame)

I personally prefer the first option, if we can get it to work in a satisfactory manner. But I'm open to the idea of the second option.

This is an area of a lot of interest for me, but I don't see myself getting time to tackle this in the near future (I'll possibly get to this by the end of the year). If someone else wants to work on this before then, I would love to help.

Cheers,
- Lalit

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.

I'll post a message here when features in this general area start getting implemented.

It's really an excellent tool for play and learning!

Thanks.

What is an appropriate age starting to use Kojo?

I'd say around 9 or 10.

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

The 2D case should be very doable, and some day in the not too distant future I plan to do some of this. 3D support is probably still further out.
Would you be interested in playing with trying to implement this? If so, I'll be happy to give you pointers and help.

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

Currently, no. This could theoretically be done, but I have not given this much thought.

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?

Offline interaction with Bjorn Regnell has resulted in the refinement of the keyboard event handling capability within Kojo. This is available in Kojo version 210711-1.

More information here: http://kojoenv.wordpress.com/2011/07/22/kojo-version-210711-released/

I'm sorry to hear about your initial negative impression of Kojo. Let's try to figure out what the problem is. Please do the following (on your Windows machine).

- Download the jar Kojo installer (kojoinstall-210711.jar)
- Open up a command prompt and go to the directory where you have downloaded the jar installer
- run java -jar kojoinstall-210711.jar

After doing this, please report what you observe (error messages etc).

I have now followed the instructions for Max/Unix and gotten it to work. I still think your Windows installer has some sort of issue. It would be wise to figure out what that might be. You are silently losing opportunities for those whose initial impression is soiled by that undesirable experience.

Jim

I'm wanting to check out Kojo via the "Kojo Story". However, I am having a problem. I have Java 1.6.0_26_b03 (64bit version) on Windows 7 Ultimate. And it is the only JDK/JRE on my system. I have a number of other Java applications installed. I downloaded the "kojoInstaller-210711.exe" and attempted to run it by double clicking on it. After giving the application permission via a Window's security pop-up, I then see an installer window pop of for all of a half-second (so quickly, I can barely tell what it is) before it disappears. And then nothing happens.

This is a terrible initial experience. I can only imagine that someone less technical than I am and who is wanting to check out Kojo would immediately abandon their mild interest given this inexplicable and obtuse response. I, however, am undaunted and am willing to work through whatever we need to do to get this working with the assumption that once we have it figured out, you will take what you learn from my configuration and update your help files. Seems like a fair trade.

Please advise on how I might proceed.

Thank you

Jim

Done.

Thanks.

Also, as a temporary workaround this works: add a key binding for "Select line" in the keymap
(maybe Ctrl + QUOTE). Then Ctr + QUOTE + ENTER will run only the selected line.

Cool!

Is there a way to get email notification when there activity on a thread?

There should be an option on the bottom right of the browser window to start watching the site. Lemme know if you run into problems getting this to work for you…

Also, as a temporary workaround this works: add a key binding for "Select line" in the keymap (maybe Ctrl + QUOTE). Then Ctr + QUOTE + ENTER will run only the selected line. As a side effect cursor moves to next line (which maybe desired in some cases).

Is there a way to get email notification when there activity on a thread?

Thanks,
Mushtaq

I see that selecting the whole line followed by Ctrl + Enter achieves the same thing.

You don't really need to select a whole line. Just select any text and hit Ctrl + Enter (or click the run button) to run it.

But it will be very convenient to add a shortcut line Alt + Enter.

Would you mind adding it as an enhancement request on the Kojo issues page: http://code.google.com/p/kojo/issues/list

I'll implement this the next time I work in that area of the code…

Thanks,
Mushtaq

PS: Thanks for making this amazing tool!

With this version you, can write stuff like:

 clear() setAnimationDelay(100) onKeyPress { k => k match { case Kc.VK_LEFT => setHeading(180) forward(10) case Kc.VK_RIGHT => setHeading(0) forward(10) case Kc.VK_UP => setHeading(90) forward(10) case Kc.VK_DOWN => setHeading(270) forward(10) } } 

And

 clear() setAnimationDelay(10) onMouseClick { (x, y) => setPosition(x, y) forward(40) right(30) forward(20) } 

Feedback welcome…

I’m using Kojo to teach kids programming in Sweden.

That's great to hear.

I think the environment is great!

Thank you.

I would like to test if a key is pressed or not
Is there an easy way of doing this?

Within Kojo, you can currently work with the keyboard in a couple of different ways:

- With turtles; here's an example:

 clear() clearOutput repeat (2) { forward(readInt("How may steps")) right(readInt("How many degrees")) } 

- With Staging shapes; here's an example:

 val S = Staging S.clear() val c = S.circle(S.point(10, 10), 100) c.setFillColor(green) // click on shape to activate key handling c.onKeyPress { k => k match { case Kc.VK_RIGHT => c.translate(-10, 0) case Kc.VK_LEFT => c.translate(10, 0) case _ => } } 

Anyway of polling the keybord with the builtin stuff?

I just played with adding builtin capability so that you could do things like the following:

 clear() setAnimationDelay(100) onKeyPress { k => k match { case Kc.VK_LEFT => setHeading(180) forward(100) case Kc.VK_RIGHT => setHeading(0) forward(100) case Kc.VK_UP => setHeading(90) forward(100) case Kc.VK_DOWN => setHeading(270) forward(100) } } 

Does that sound useful for the kinds of things that you are trying to do.
I'm open to other API suggestions (and I do need to look at the Processing stuff)…

Cheers,
- Lalit

I’m using Kojo to teach kids programming in Sweden.
I think the environment is great!

I would like to test if a key is pressed or not (without haning) in order to enable the kids make easy games where they control the turtle in realtime using the keyboard.

Is there an easy way of doing this?
I tried to look in codecompletion for Staging. , but found no keypressed etc as there seem to be in the corresponding processing environment: http://www.processing.org/reference/

Anyway of polling the keybord with the builtin stuff?

Cheers
Bjorn

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).

I put a link to kojo in a comment on Phil Wadler's blog where he has been discussing languages for kids

Great!

Needless to say kojo doesn't have a low ceiling.

Exactly right. Kojo's got a low floor and a high ceiling (courtesy Scala).

From your comment:

My 7-year old grandson loves it, but it does need a bit of adult expertise to explain error messages at the moment. The author is working on it.

I'm afraid this is on hold right now due to time/prioritization constraints.
After I added Stories to Kojo, the subset of Scala used by kids became much bigger (and the task of defining language levels for Kojo became much more complicated).
Also, the kids that I work with seem to get by just fine when they encounter errors. Most of them don't pay much attention to the error messages, but, given that they know (with Kojo's help) the exact line number where the error is, they are able to examine the location of the error - and (mostly) figure out and recover from the problem.

Cheers

Marco

I have created a page with high-level instructions on integrating a Java library into Kojo:
http://code.google.com/p/kojo/wiki/IntegrateLibrary

This should hopefully get you going. If you run into any problems, or have any questions, let me know.

Cheers,
- Lalit

::
Lalit Pant
Lead Developer, Kojo

Thanks in advance

Marco

- Fire up Kojo (new version info below)
- Write some code; run it to make a sketch
- Upload your work (code + sketch) to the Code Exchange by clicking the rightmost button in the Script Editor Toolbar

The Code Exchange is running at: http://www.kogics.net/codeexchange0

Some Features available within the Code Exchange are:

• Viewing Recent entries
• Voting on entries
• Viewing Popular entries (as per votes)
• Having discussions about entries
• Viewing entries for particular users
• Competitions (very basic support for now)

Update: The Code Exchange is now live. More information here:
http://kojoenv.wordpress.com/2010/10/02/announcing-the-kojo-code-exchange/

I haven't had a chance to dig into this (I'm expecting that I'll have to dive into the Netbeans API wormhole to figure the incompatibility out; something that I'm hoping that I can delay till the release of the next version of Netbeans, to make the effort worth it).

/Applications/NetBeans/NetBeans 6.9.1.app/Contents/Resources/NetBeans/harness/build.xml:168: Cannot compile against a module: /Applications/NetBeans/NetBeans 6.9.1.app/Contents/Resources/NetBeans/ide/modules/org-netbeans-modules-csl-api.jar because of dependency: org.netbeans.modules.csl.api/1 > 1.11.1.1.1.1.1
BUILD FAILED (total time: 12 seconds)

I'll try again and follow the instructions this time :-).

Just one suggestion - how about if we move the Commands section to a different page, and link to it from this page?

Then, we can also link to the Commands page from the End-user documentation page on the Kojo website.

Come to think of it, the StagingModule page also pretty much has End-user documentation, so the documentation page on the Kojo website would also link to this.

Note. The documentation page on the Kojo website does not yet exist (there's only an ebooks page right now). I'll add the documentation page after we're done with this discussion.

This page is primarily for developers, following the link from the StartCoding page. End users should find it informative too, though.

The "Corresponds to" column mentions Logo primitives that do roughly the same job. It doesn't add much for Kojo users per se; my thought was that it would be easier for Logo users or people who follow Logo textbooks to port Logo scripts that way.

At this point, I'd appreciate feedback and suggestions: does it explain the right things the right way?

Lemme know how that goes…

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…

I'm currently doing development for Google App Engine. This would be an ideal environment for kojonet: scalable, flexible and we can write in scala. The free quota is pretty good, but maybe Google would support an enhanced free quota for a worthwhile educational cause.

An example game that might be simple enough for the code to be understandable might work like this: The graphical display shows a race course. Players can choose the engine size of their car. Heavier engines give better acceleration and braking in the direction of travel, but less to the left or right (so slower through the corners). The driver specifies the direction of acceleration by moving the mouse in the elliptical acceleration envelope (which would move around with the car). One can imagine competing against other players on the same course: at least remembering high scores for different age groups. Many other simple games are possible.

I think security and privacy will be important. We want to know that the people involved are real children, and perhaps know their age. On the other hand we don't want real names and other contact-relevant info to be visible to the world. We want to know who the parents or teachers are as well. Perhaps a token credit card charge through Google Checkout? These are matters that need further discussion.