MPS plugin for IntelliJ IDEA

MPS 2.5 can be run as a plugin for IntelliJ IDEA enabling MPS-based DSLs to be used directly in a Java IDE and so interoperate tightly with the Java code. Custom languages can be exported from MPS as IDEA plugins as well. IntelliJ IDEA became another platform for MPS-based DSLs use, besides standalone Java applications and MPS itself.

There are several aspects of integrating MPS into IntelliJ IDEA:

Dependencies analyzer

The Dependencies Analyzer can report dependencies among modules or models. It can be called from the main menu or from the popup menu of modules/models:


The interactive report, shown in a panel at the bottom, allows the user to view usages of modules by other modules. The panel on the right side displays modules and models dependent on the module selected in the left-hand side list.

Module Dependencies Tool

The Module Dependencies Tool allows the user to overview all the dependencies and used languages of a module or a set of modules, to detect potential cyclic dependencies as well as to see detailed paths that form the dependencies. The tool can be invoked from the project pane when one or more modules are selected.

Module Dependency Tool shows all transitive dependencies of the modules in the left panel. Optionally it can also display all directly or indirectly used languages. It is possible to expand any dependency node and get all dependencies of the expanded node as children. These will again be transitive dependencies, but this time for the expanded node.

Select one or more of the dependency nodes in the left panel. The right panel will show paths to each of the selected modules from its "parent" module. You can see a brief explanation of each relation between modules in the right tree. The types of dependencies can be one of: depends on, uses language, exports runtime, uses devkit, etc. For convinience the name of the target dependent module is shown in bold.

There are two types of dependency paths: Dependency and Used Language. When you select a module in the Used Language folder in the left tree, the right tree shows only the dependency paths that introduce the used language relation for the given module. To show "ordinary" dependencies on a language module, you should select it outside of the Used Languages folder (e.g. the jetbrains.mps.lang.core language in the picture below). It is also possible to select multiple nodes (e.g. the same language dependency both inside and outside of the Used Language folder). In that case you get a union of results for both paths.

For tracking runtime dependencies in addition to the "compile-time visible" ones, you should check the Runtime option in the toolbar. The runtime dependencies are marked with a "(runtime)" comment.

The default order for dependency paths is by their length starting from the shortest. However, there are paths that cannot be shown - paths that have the same tail part as one of the already shown path. It is still possible to display all such paths in the right tree with the "Show all paths" option. For these only the starting (distinct) part of the path is shown, while the symbols "... -->" mean that there is already a path shown in the tree somewhere above that describes the rest of the dependency path. You can follow the path by double-clicking its last element.

The modules in the left tree that participate in dependency cycles are shown in red color. It is possible to see paths forming the cycle by selecting the module dependency that refers to the parent or, for the user convinience, by using the popup menu:

For some types of dependencies the pop-up menu offers the possibility to invoke convenience actions such as Show Usages or Safe Delete. For the "depends on" dependencies (those without re-export) Dependencies Analyzer will be invoked for the Show Usages action.

Changes in the Refactoring language

In order to make the structure of MPS core languages more consistent and clear, the Refactoring language has been changes considerably. Several new and easy-to-use constructs have been added and parts of the functionality was deprecated and moved into the Actions language.

The UI for retrieving the refactoring parameters has been removed from the refactoring language. Choosers for parameters are no longer called, it is not allowed to show UI in init (e.g. ask and ask boolean) and keystroke has no effect. All this functionality should be moved to an action correspondent to the refactoring.

The following constructs have been added to the refactoring language:

It is necessary to manually migrate existing user refactorings. The migration consists of several steps:

Suppressing errors

One of very effective ways to maintain high quality of code in MPS is the instant on-the-fly code analysis that highlights errors, warnings or potential problems directly in code. Just like with other code quality reporting tools, it is essential for the user to be able to mark false positives so that they are not reported repeatedly. MPS now enables the developers to suppress the reported problems directly in the editor (and in the model checker).

If a node is an instance of a concept, which implements the ISuppressErrors interface, all issues in this node and so its children won't be shown. For example, comments in BaseLanguage implement ISupressErrors. It is also possible to define child roles, in which issues should be suppressed, by overriding the boolean method suppress(node<> child) of the ISupressErrors interface.
Additionally, if a node has an attribute of a concept that implements ISuppressErrors, issues in such node will be suppressed too. There is a convenience default implementation of an ISuppressErrors node attribute called SuppressErrorsAttribute. It can be applied to only those nodes that are instances of ICanSuppressErrors.

An example of using the SuppressErrorsAttribute attribute and the corresponding intention.

There is an error in editor:


BaseLanguage Statement implements ICanSuppressErrors, so the user can apply the highlighted intention here:

Now the error isn't highlighted any longer, but there is a newly added cross icon in the left pane. The SuppressErrorsAttribute can be removed either by pressing that cross or by applying the corresponding intention

Extensions support

Extensions provide a possibility to extend certain aspects of a solution or a language, which are not covered by the standard language aspects and the plugin mechanisms.

Support for extensions exists in

Quick howto

  1. Create an extension point
  2. Create one or more extensions
  3. Both the extension point and the extension must be in the plugin model
    1. Each extension must provide a get method, returning an object
    2. Each extension may opt to receive the activate/deactivate notifications
    3. An extension may declare fields, just like classes can

Extension language

The language jetbrains.mps.lang.extension declares concepts necessary for building extensions.

Extension point

The ExtensionPoint concept represents an extension point. The extension object type must be specified as a parameter.


The Extension concept is used to create a concrete extension.

Accessing extension point

An extension point can be accessed by reference using extension point expression.

Accessing extension objects

An extension point includes a way to access all objects provided by its extensions.

Objects returned by the extensions have transient nature: they may become obsolete as soon as a module reloading event happens. It is not recommended to e.g. cache these objects. Instead is it better to get a fresh copy each time.

Java API

public interface Extension<T> {

  String getExtensionPointId ();

  T get ();

  void activate ();

  void deactivate ();

public class ExtensionPoint<T> {

  public ExtensionPoint (String id, Class<T> type) { ... }

  public Class<T> getType () { ... }

  public Iterable<Extension<T>> getExtensions () { ... }

  public Iterable<T> getObjects () { ... }

  public String getNamespace () { ... }

  public String getId () { ... }


Extension points and extensions are managed by the ExtensionRegistry core component.

Showing the current status of Saving Transient Models in the status bar

A button in the status bar allows the user to enable and disable saving of transient models with one click.

If transient nodels saving is enabled, this button shows a notification popup when generation starts.

The popup notification can be disabled in Settings -> IDE Settings -> Notifications -> Saving Transient Models Is On.

New XML language

New language named jetbrains.mps.core.xml was introduced in MPS 2.5. This XML language was designed in accordance with XML specification. From now it is recommended yo use this language if you need to work with XML in MPS. All the other XML languages will be deprecated in future.

Custom persistence for MPS models

With the improved jetbrains.mps.lang.stubs language it is possible to declare stubs model manager supporting model saving functionality. Using this extension point it is possible to teach MPS how to interoperate with any custom syntax.

Make process improvements

mps.* ANT tasks were reimplemented to eliminate dependency on IDEA platform modules. This should reduce loading time and so speedup mps.* tasks execution.

Editor improvements

Generator improvements

Collections language improvements

Build language redesigned

New Scopes

Version control

More reliable merge conflict handling


New Productivity Guide

Good command of the tools is undoubtedly one of the attributes of an efficient developer. MPS 2.5 can monitor your actions and give you statistics on how frequently you use its most prominent editing and refactoring capabilities. Go to Help | Productivity Guide to see how well you do:

Additionaly, we've prepared a list of a couple dozen tricks you could learn through the Tip of the Day window to become more fluent with the MPS editor:

MPS.Classpath module removed

There are four specific modules used to expose all available Java API of the platform and MPS as JavaStub models:

These modules were created as a substitution to MPS.Classpath module existing in previous version. Talking briefly, MPS.Classpath was split in those four modules to isolate core code from any dependencies on UI-/Editor-/Platform- specific APIs.


One of the goals for MPS 2.5 release was making our platform modular. By exploring Plugins page in setting dialog it's easy to see increased number of plugin forming MPS 2.5 platform. If some plugins are not necessary for current tasks those plugins can be simply switched of increasing performance of the platform. Same trick can be used to create reduced IDE for some specific DSLs based on MPS.


If you are already using MPS in your projects, it definitely make sense to read our migration guide with the detailed description of migration process.