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This is a readme file for the developers.


Java Development Kit (required JDK8 or higher)

You can follow the instructions depending on the type of your machine.

To make sure that everything works you should be able to call java -version and javac -version from a Terminal.

Apache Maven


  • Download from package manager (e.g. sudo apt-get install maven)


  • If your version is prior to Mavericks, Maven comes pre-installed with XCode. Otherwise, download it from a package manager or from and follow the instructions on the webpage.


  • Go to and download the zip with the binary distribution. Unzip it in your desired location and follow the installation instructions on the webpage.

Maven usually requires setting an environment variable JAVA_HOME pointing to the installation directory of the JDK (not to be mistaken with JRE).

You can test if it works by calling mvn -version in a Terminal. This will provide the information about the JDK Maven is using, in case it is the wrong one.

Git - command line

Having a GUI client is not enough. Most distributions have an installation option to make git accessible in the command line too.


Checkout this directory in your desired location and call mvn package from the main directory to build the distribution. For convenient usage, you can update your $PATH with k-distribution/target/release/k/bin (strongly recommended, but optional).

You are also encouraged to set the environment variable MAVEN_OPTS to -XX:+TieredCompilation, which will significantly speed up the incremental build process.

IDE Setup


You should run K from the k-distribution project, because it is the only project to have the complete classpath and therefore all backends.


In order for K to run correctly in an IDE, it is necessary that the correct environment variables be set.

Mac OS X

PATH=$PATH:<release>/lib/native/osx DYLD_LIBRARY_PATH=$DYLD_LIBRARY_PATH:<release>/lib/native/osx

Windows x86


Windows x64


Linux i386

PATH=$PATH:<release>/lib/native/linux:<release>/lib/native/linux32 LD_LIBRARY_PATH=$LD_LIBRARY_PATH:<release>/lib/native/linux32

Linux amd64

PATH=$PATH:<release>/lib/native/linux:<release>/lib/native/linux64 LD_LIBRARY_PATH=$LD_LIBRARY_PATH:<release>/lib/native/linux64


To autogenerate an Eclipse project for K, run mvn install -DskipKTest; mvn eclipse:eclipse on the command line, and then go into each of the kore' and tiny' directories and run `sbt eclipse'. Then start eclipse and go to File->Import->General->Existing projects into workspace, and select the directory of the installation. You should only add the leaves to the workspace, because eclipse does not support hierarchical projects.

IntelliJ IDEA

IntelliJ IDEA comes with built-in maven integration. For more information, refer to the IntelliJ IDEA wiki

Run test suite

To completely test the current version of the K framework, run mvn verify. This normally takes roughly 30 minutes on a fast machine. If you are interested only in running the unit tests and checkstyle goals, run mvn verify -DskipKTest to skip the lengthy ktest execution.

Changing the KORE data structures

If you need to change the KORE data structures (unless you are a K core developer, you probabably do not), see Guide-for-changing-the-KORE-data-structures.

Build the final release directory/archives

Call mvn install in the base directory. This will attach an artifact to the local maven repository containing a zip and tar.gz of the distribution.

The functionality to create a tagged release is currently incomplete.

Compiling definitions and running programs

Assuming k-distribution/target/release/k/bin is in your path, you can compile definitions using the kompile command. To execute a program you can use krun.

For running either program in the debugger, use the main class org.kframework.main.Main with an additional argument -kompile or -krun added before other command line arguments, and use the classpath from the k-distribution module.

Cross platform compilation

To build a version of the K framework for a platform other than the current version, you can specify the OS and architecture using profiles. For example, to build a 32-bit windows release of the K framework, run mvn install -P windows -P x86 -DskipTests -DskipKTest.

To view the platform being used by a particular build, run the mvn help:active-profiles target.


Common error messages:

  • Error: JAVA_HOME not found in your environment. Please set the JAVA_HOME variable in your environment to match the location of your Java installation.

    • Make sure JAVA_HOME points to the JDK and not the JRE directory.
  • [WARNING] Cannot get the branch information from the git repository: Detecting the current branch failed: 'git' is not recognized as an internal or external command, operable program or batch file.

    • ``gitmight not be installed on your system. Make sure that you can executegit` from the command line.
  • 1) Error injecting constructor, java.lang.Error: Unresolved compilation problems: The import org.kframework.parser.outer.Outer cannot be resolved Outer cannot be resolved

    • You may run into this issue if target/generated-sources/javacc is not added to the build path of your IDE. Generally this is solved by regenerating your project / re-syncing it with the pom.xml.
  • [ERROR] Failed to execute goal org.apache.maven.plugins:maven-compiler-plugin:3.1:compile (default-compile) on project k-core: Fatal error compiling: invalid target release: 1.8 -> [Help 1]

    • You either do not have Java 8 installed, or $JAVA_HOME does not point to a Java 8 JDK.

If something unexpected happens and the project fails to build, try mvn clean and rebuild the entire project. Generally speaking, however, the project should build incrementally without needing to be cleaned first.

If you are doing work with snapshot dependencies, you can update them to the latest version by running maven with the -U flag.

If you are configuring artifacts in a repository and need to purge the local repository's cache of artifacts, you can run mvn dependency:purge-local-repository.

If tests fail but you want to run the build anyway to see what happens, you can use mvn package -DskipTests.

If you still cannot build, please contact a K developer.

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