In connection with that transition the MPS blog has moved to the new place: http://blogs.jetbrains.com/mps

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MPS is released under the Apache License version 2.0!

I wish the resolution be better but Sebastien's comments are quite insightful and enjoyable.

• The Simplest Language


• Simple Base Language Extensions

P.S. In addition to my Russian blog here. I have an English blog on MPS here. I will mostly write to it because wordpress provides spam protection and has better interface than movable type.

It is about two weeks since previous build and we are planning to fire fresh builds more often then before: on bi-weekly basis or about that.

The second good news is that MPS bug-tracker is now open for external submitters. (I repeat myself but can’t help mentioning that the JetBrains bug tracker is developed using MPS).

I also would like to thank Tracy Snell for composing of updated Getting Started with MPS tutorial.

It is actually first ever external contribution to the MPS project!

The most important new features:

• It's possible to work with MPS without IntelliJ IDEA


• Generator tracer: easy way to find out why generator behaves this way.


• Improved transient models saving


• Unified DotExpression across the languages.


• Ability to write Intentions


• Ability to write custom Find Usages


• Ability to write plugins from MPS


• Logable refactoring language: it's possible to define refactorings which will be written to a log and replayed later


• Improved editor UI: inspector now behaves in a different way


• New example: language for complex numbers support

This event is noteworthy because the bug tracking system the TeamCity project has migrated to (codename Charisma) is a product which is completely developed in MPS.
It is not a ‘Hello world’ kind. It is quite exquisite and capable web application which we have been using internally for a while and now it is available for external users.

Charisma is 100% developed using the language oriented approach and its deployment code is 100% generated. Really, it's the 200% LOP application!:)

The Charisma solution includes about 50 model files of total size about 10MB. Concurrently, the Charisma team created dozens of DSLs which cover all required problem domains from general domains like XML to more narrow ones like RSS to most specific like ‘user management’.

The Charisma development has also generated a great deal of feedback which led to vast improvements of MPS performance, UI and ‘language design’ languages (aka bootstrap languages). MPS is becoming a really great tool!

Frustrating, of course, but this problem is unavoidable. Over a language evolution, models written in this language become outdated.
Actually, this happens constantly in our every day development. Our team develops various DSLs and solutions concurrently and it is just not possible to have all models updated after changes in their languages.

Fortunately, MPS supports scripts which can automate migration of models to new version of language.
Language migration scripts are part of language definition and they are available in any context where the language has been used.

A couple of such scripts can be found in build 470.

To begin with, let’s open BaseConcept in jetbarins.mps.core language (open any project in MPS, press Ctrl-N and type ‘BasC’).

There is a set of concept properties with name starting with “deprecated”. To find what was deprecated in build 470, select ‘deprecated_next_after_415’ property and press Alt-F7 (search usages).

Double-click on selected node to open it in the editor.

Obviously, all usages of the deprecated ConceptRightTransformMenuPart concept should be rewritten using new ConceptRightTransformPart concept.

To find usages, first press Ctrl-W twice to make proper selection and then press Alt-F7.
In my example project 'find usages' found one instance and few other usages.

First let’s open ‘instance’ in editor view:

When a concept is changed or replaced, we remove corresponding support in generator, typesystem etc. but keep its structure and editor to let old models to be opened without crashing. Editor is usually modified to warn of the obsolete feature usage.

One of the other usages is in script named ‘MigrateFrom415’. Let’s open it too.

The model transformation is done in ‘do’ block. It is written in BaseLanguage (Java-like language) but Java here is almost not recognizable because of heavy usage of smodel language.
The smodel language is BaseLanguage’s extension for manipulation with MPS models.

Now let’s run this script. This can be done from main menu or from model’s popup menu. Actually, I could do it just after MPS is started. All steps above are not necessary.

Script will perform search usages and open refactoring view:

That gives us last opportunity to take a look at the models before they are transformed:

‘Do Refactor’ will update the model:

New features:

• MPS modules reference each other by their fqname rather than by path relative to a reference file


• Performance optimizations for large models


• meet and join types in HELGINS

• Language development is now possible almost without Java IDE. Only weaving rule context queries have to be written in Java
• New Helgins typesystem. You can now write BaseLanguage code in helgins rules.
• New introduction to MPS. You can read it online here or open it from help menu in MPS.

Probably, something about MPS in Neal Ford keynote on January 18 at CodeMash.

Happy New Year to everybody!

He will bring MetaEdit with him but everybody is invited to bring his/her own tool.
I wonder if there is somebody out there who will bring MPS.
We can provide the latest build and 24/7 technical support:)