Background
Karel The Robot is a simple teaching environment for imperative programming basics. The original idea was developed in the 1970s by Richard Pattis at Stanford University.
This project started in 2012 due to dissatisfaction with the available Karel environments, and also to gain practical experience with Scala. Since then, thousands of German university students have been introduced to the basics of imperative programming via this project.
In 2017, the Scala code was migrated to Kotlin, hoping to simplify future maintenance.
How do I compile karel into an executable jar?
git clone https://github.com/fredoverflow/freditor
cd freditor
mvn install
cd ..
git clone https://github.com/fredoverflow/karel
cd karel
mvn package
The executable karel.jar will be located inside the target folder.
How do I start the system?
Karel The Robot requires Java 8 or newer to run. Make sure you have Java installed!
On Windows, you can simply run a jar by double-clicking on it.
On other operating systems, open a terminal where the jar lives and write:
java -jar karel.jar
Java animations tend to stutter on Linux.
Replacing xrender with opengl may help:
java -jar -Dsun.java2d.opengl=True karel.jar
How do I save my code?
The code is automatically saved to a new file each time you click the start button.
The save folder is named karel, and it is located in your home directory.
The full path is displayed in the title bar.
Keyboard Shortcuts
F1 moveForward();
F2 turnLeft();
F3 turnAround();
F4 turnRight();
F5 pickBeeper();
F6 dropBeeper();
F7 onBeeper()
F8 beeperAhead()
F9 leftIsClear()
F10 frontIsClear()
F11 rightIsClear()
F12 start / step into / reset
Tab or Enter auto-indent
Ctrl Space auto-complete
Ctrl D delete line
Ctrl C copy
Ctrl X cut
Ctrl V paste
Ctrl Z undo
Ctrl Y redo
How do I install IntelliJ IDEA?
Download the Community Edition zip or tar.gz from https://www.jetbrains.com/idea/download and extract it wherever you like.
Navigate to the bin folder and run the idea.bat or idea.sh script.
Then follow these instructions:
Import IntelliJ IDEA Settings From...
(o) Do not import settings
OK
JetBrains Privacy Policy
[x] I confirm that I have read and accept the terms of this User Agreement
Continue
Data Sharing
Don't send
Skip Remaining and Set Defaults
How do I import karel into IntelliJ IDEA?
- If there are no projects open, pick the Import Project option from the Welcome to IntelliJ IDEA screen.
- Otherwise, pick File > New > Project from Existing Sources...
Windows: C:\Users\fred\git\karel
Linux: /home/fred/git/karel
OK
Import Project
(o) Import project from external model
Maven
Next
Next
Next
Please select project SDK. This SDK will be used by default by all project modules.
+
JDK
Windows: C:\Program Files\Java\jdk1.8.0_...
Linux: /usr/lib/jvm/java-8-openjdk-amd64
OK
Next
Finish
Tip of the Day
[ ] Show tips on startup
Close
How do I start karel from within IntelliJ IDEA?
karel/src/main/kotlin/Main.kt (right-click)
Run 'MainKt'
What IntelliJ IDEA settings do you like to change after install?
File > Settings...
- Keymap
- Eclipse
- Editor > Font
- Font: Fira Code (
sudo apt install fonts-firacode) - Size: 20
- Font: Fira Code (
- Editor > General > Code Folding
- One-line methods
- Editor > General > Appearance
- Caret blinking
- Show intention bulb