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  • What's New in 2021.1

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Zoom feature in editor

Font size can be quickly adjusted in the currently open editor window by holding Control and rolling the mouse wheel. Font size is not persistent so when the file is re-opened the text size is reset to the default value. You can enable/disable the feature in settings in the Editor / General section: Change font size with Ctrl+Mouse Wheel.

Improved access to $LOOP$ macro variables


The MPS model viewer is enabled for the merge commits in git log. The viewer shows three panels - the center panel for the merged model and left and right panels for the models of two merged branches.


Version Control: Root annotation improvements

New options in the BaseLanguage comments



BTestCase finally generates into JUnit4 test class

No longer JUnit3 and its junit.framework.TestCase superclass limitation.


Improved performances on indent layout

The indent layout implementation has been made incremental in some key cases, which will reduce the rendering time for big models in languages using mainly indent layout (such as baseLanguage). This feature can be disabled with the vm option mps.indent_layout.disable_incremental in case of trouble.


Java Compiler for MPS modules with Java facet

A lot has been changed in approach to Java compilation of MPS modules. We started this change to address one of our top-voted issues, Annotation Processing support ( We switched MPS Java Compiler infrastructure to utilise set of APIs. Now, MPS can use any compiler that implements this standard API, as of MPS 2021.1 we run with a default compiler configured for the API, with an option to use Eclipse Java Compiler, if present. When ECJ libraries are in classpath, you may switch MPS to use Eclipse Java Compiler with '' as the system property (e.g. by editing 'mps.vmpoptions'). In case you experience unrecoverable issues using new compiler infrastructure, there's also an option to switch back to legacy mechanism of direct ECJ API use, put 'ecjlegacy' as the value for '' system property.

Beside, now we run compiler with '-release' option, with version specified in project preferences (Preferences -> Java Compiler). This option is a bit more strict than combination of -source/-target options MPS relied on in previous releases, as it controls uses of library APIs that were available in certain releases. You may need to bump up Java version in your project in case you encounter compilation issues due to use of APIs not available in certain release.

Updated transform statement in GenPlan declaration

To evolve GenPlan extensibility story, there's a new mechanism to include languages/generators that are unknown to the plan designer. Now, with `transform` statement, language designer may include a language that targets or extends a given one. Language B 'targets' Language A means B language's generator produces constructs of Language A.

Control visibility of modules distributed with your plugin

For a long time, MPS assumed all modules coming from language plugins were visible to end user. With number of languages growing, as well as complexity of plugins, there are cases when Language Designer want to hide certain modules not to confuse/overwhelm end user with huge number of unrelated languages or solutions. Plugins tell MPS about modules they contribute by means of `com.intellij.mps.LanguageLibrary` extension point. Now, extensions to the point may provide optional `hide="true"` attribute, that makes modules of the plugin eligible to filtering by pattern specified with `com.intellij.mps.VisibleModuleMask` (MPS-26427). Most MPS plugins now bear the flag, facilitating filtering of MPS own languages in case Language Designer needs to hide them. MPS provides masks for its own modules as part of `jetbrains.mps.ide.devkit` plugin, authors of a custom IDE generally don't include this plugin into a distribution, and have full control over visible modules in their product.