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Navigating the MPS Sources

This page describes the folder structure of the MPS sources that you can check out with Git from ⧉. The readme of the repository contains more information.


The artifacts directory contains the artifact-related settings. Artifacts | IntelliJ IDEA ⧉ contains more information. Artifacts in this project are the generated jar files such as mps-core.jar and vcs-core.jar:

mps artifacts dialog

The directory also contains settings for code styles, copyright info, and enabled inspections. The paths to the used libraries (*.jar) are also specified in the libraries subfolder. The run configurations, search scopes as well as many other IntelliJ-specific project settings,


This folder also contains run configurations and scopes but also other settings:

  • codeStyleSettings.xml: style settings used for Base Language (e.g., default field and parameter prefix)
  • compiler.xml: the version of the Java compiler (currently: 11)
  • encodings.xml: encoding of the files (should be: UTF-8)
  • migration.xml: list of executed MPS migrations in the current project
  • misc.xml: miscellaneous settings (e.g., settings of favorites manager)
  • modules.xml: a list of modules of this project MPS loads on startup
  • vcs.xml: version control settings
  • version.xml: project version (not used anymore)
  • settings of different components (e.g., console history, messages view tool, project view)


This folder contains executable files for the different operating systems (Windows, Mac, Linux). All of them use the executable fsnotifier to react to file system changes. OS-specific files:

  • Linux

    • libdgbm: GNU dbm ('gdbm') is a library of database functions that use extendible hashing and works similarly to the standard UNIX dbm function source ⧉
    • restarts MPS
  • Mac

    • libmacscreenmenu64.dylib: native access to the Apple menu bar ⧉.
    • libnst64.dlib: native access to the Apple MacBook Pro Touch Bar ⧉. The library is called NST (NextStep Touch Bar).
    • printenv: prints the environment variables
  • Windows

    • breakgen(64).dll: gracefully shut down a running process (not possible with Java).
    • elevator.exe: a sudo-like tool for Windows to deal with UAC (source ⧉)
    • IdeaWin32/64.dll: native file system functions
    • launcher.exe: launches MPS
    • restarter.exe: restarts MPS
    • runnerw.exe: an old library for Windows process management. WinP ⧉ superseded it.
    • WinProcessListHelper.exe: lists Windows processes
    • WinShellIntegrationBridge.dll: integration with the Windows shell
    • wslhash: hash calculation (?) for the Windows Subsystem for Linux ⧉
    • wslproxy: proxy (?) for the Windows Subsystem for Linux ⧉


The dependency manager of the project is Apache Ivy ⧉. The corresponding folder is build/ivy. The build tool is Apache Ant ⧉. The artifacts folder contains the generated jar files. An artifact might look like this:

  • languages: contains MPS languages
  • modules: contains Java classes
  • lib: Jar dependencies
  • META-INF: contains the plugin configuration file ⧉
  • contains the MPS version and IntelliJ plugin this artifact belongs to.

The dependencies folder contains the Gradle configuration properties ⧉.

home/.ant/lib contains additional Java libraries that can be used with Ant.

The resources folder contains image resources as well as the following files:

The tests folder contains Ant scripts for executing tests. The tools folder contains scripts for signing and creating DMGs and a version of the Java Runtime Environment and NSIS (Nullsoft Scriptable Install System) for creating an installer for Windows. The other XML files are also Ant scripts for different tasks (getting dependencies, building MPS languages, migration projects, etc.). The and can be used to run the build and tests on Linux/Mac. update.xml lists all MPS versions and helps with the automatic MPS update management.


The aspects folder contains the languages for the language aspects. The baselanguage folder contains the Base Language implementation and all its extensions, such as extension methods, closures, or the collection language.

The folder devkit contains the four main devkits:

  • jetbrains.mps.devkit.bootstrap-languages: contains all the jetbrains.mps.lang languages
  • jetbrains.mps.devkit.general-purpose: Base Language + smodel + text + quotation language
  • jetbrains.mps.devkit.language-design + the previous 2 devkits + an intermediate language for baselanguage (baseLanguageInternal) + a language for resources
  • jetbrains.mps.devkit.templates: general-purpose + generator languages


It contains core languages of MPS such as loaders for Java stubs, classes for persistence, language checkers, make classes, and runtime classes for smodel such as and


This folder contains all core languages such as smodel, quotation, access, quotations, and pattern.


Everything related to the make facet is in this folder.


This folder contains all stub models provided by MPS, for example, stubs for annotations (like JetBrains annotations ⧉), Java core classes (JDK, e.g., java.util.List), and all MPS-related Java classes are located in solutions that start with the naming pattern MPS.* (e.g., MPS.Core).


This folder contains classes for accessing MPS from Java (e.g., MPSEnvironment) and other tool-related classes, such as accessing Ant from Java.


This folder contains languages and solutions for the following platform features:

  • build language
  • console
  • HTTP server
  • make
  • migrations
  • model checker
  • Java to MPS parsing
  • spell checker
  • debugging information (traceInfo)
  • version control
  • integrations with the IDEA platform
  • integration for MPS plugin into IntelliJ IDEA


This folder contains the samples that MPS ships with. When first accessed through the start screen, MPS unpacks them automatically into a folder in the home directory.


This folder contains classes for executing tests and all kinds of tests, such as generator tests or tests for the constraint aspect.


This folder contains subfolders for:

  • MPS debugger ⧉
  • Context actions ⧉
  • editor related actions
  • run configurations + execution of Base Language and other languages
  • refactorings
  • UI components and tools such as the dependency viewer, the new module dialog as well as different finders
  • all other actions (jetbrains.mps.ide and jetbrains.mps.ide.mpsdevkit)
  • editor tabs for the various language aspects