About his forum

Maybe is a sign that people are starting to use this forum but recently I saw a spam comment. Unfortunately there is no way to report it...

Also, the only topic we can choose when posting is "MPS" but we have to explicitly select because the default choice ("-") is not valid. Maybe it would make sense to MPS to be the default topic.


Hi Federico,

when I post a new topic, "MPS" is actually selected as a default, but I agree that this option seems to be meaningless atm. I assume that more jetbrains topics might be included in the future. However, since one already posts in the context of MPS, I would have assumed to find more fine-grained topics here, i.e. "Editor", "Migration", "Installation", "Newbie" or something like that.

While I appreciate that the UI of the forum here has gotten a bit cleaner, my main complain is that this seems to be a pretty lifeless community, just looking at the number of unanswered questions. Also, when I find a thread that could bear an answer for a problem I'm searching for, the answers seem to be imprecise at best, which makes using MPS rather frustrating more often than not. I still like the idea of projectional editing and LOP, but I've yet to find an implementation / community that puts reasonable effort in the UX. I liked some of the stuff we were doing over at Intentional Software, with interesting debugging tools, visualizations, and layout, but that's the opposite of an open community ;)

Anyways, I hope that MPS will get more traction and become a stronger community, like, for example, what was and is happening to Elm. I'm also still very curious what jetbrains is doing with their jetpad stuff and if and how this will influene MPS. Any ideas?




Hi Robert,
I agree that right now the forum seems lifeless in the sense that many questions remain unanswered. However I am happy to see the number of questions growing, w.r.t. to the previous years. The people at Jetbrains have answered most questions for years and maybe now they cannot cope with the growing number of questions, I am not sure.

However I think that as a community we should start contributing more and more: maybe helping others by answering questions, maybe writing more tutorials, blog posts, articles on MPS.

Some years ago we discussed building a shared blog about MPS but the idea did not take off.

I tried writing about MPS and I have seen others doing so like Eugen Schindler or the people at Itemis. Maybe we should do more and exchange more.


I would be also very interested into JetPad but it seems a dead experiment to me: I do not know if they are working on it internally but from outside and I did not capture any recent sign of life on that.


Hi guys!

Regarding jetpad, it's not dead at all. This is an app based on it, you can try it out


And a small part of MPS team is working on a web-editor based on jetpad projectional editing framework. Federico, you say you haven't seen sings of activity on jetpad, but the thing is most of jetpad is closed-source now. Including jetpad-projectional.



Thanks for sharing the link to the app, it looks interesting. Are there any events or dates you can share where these technologies might be presented, like a conference or a workshop or something?


I found this presentation from Daniil: https://www.infoq.com/presentations/projectional-editor

I am looking forward to hearing more!


Thanks for the link Federico, I watched that talk some time ago.

I don't want to sound rude but I think all those attempts of improving the UX for projectional editors are in a sense too technical and done by people way too involved in the implementation of the projectional platform, kinda "not seeing the wood for the trees", and I doubt that actual UX experts, with a deep understanding of interaction design, affordance, user studies, and the likes, have been involved in those developments.

Markus Völter et al. wrote a paper on the topic (though none of the authors seem to have a strong background in UX research / design either): http://www.voelter.de/data/pub/projectionalEditing-sle2014.pdf

Their user study shows that MPS features many mitigation techniques to address problems of projectional editing, but it also requires users to have additional training and they repeatedly state a high learning curve in order to become fluent in those mitigation techniques. I definetly have to give the paper another read to recall all the details, but as I remember all the participants of the study have been professional developers with at least a basic familiarity of MPS. I mention this because I think, especially for (business) DSLs, there is a lot of room for different results doing a similar study. I've never gotten around to do my own studies, so those are nothing but claims, but I think it is worthwhile to rethink projectional editing and also how it can be utilized by editor and interaction languages.


Markus is definitely the expert in this area and all of this work on MPS are quite interesting.

In my opinion users who are not developers tend to complain less about projectional editing, probably because they did not invest years becoming proficient at using textual languages.

Itemis have been working on grammar cells which permit to define a text-like editing experience using projectional editors and without a huge effort in defining the editors. It is something worth a look.

My interest for MPS is also due to the fact that it seems the only projectional editor mature enough that we can actually use it in projects and get feedback by real users. I am using it in industrial projects and I am quite happy with the results. Sure, there are things to improve and as a community we are still figuring best practices out.

I think we are getting to the point where we can start involve UX people and refine the concepts because Jetbrains have proved that the basic idea can work.


I agree with all your points. I just used MPS in a industrial project as well, and it was yet again quite interesting to see how users assess their first experiences with MPS. 
It's a shame that the intentional domain workbench is such a closed project. I'm not saying that they have all the answers (certainly not), but I think it would be a very welcome sight to have more than one mature language workbench that uses projectional editing, since their platform features some quite different ideas.
Maybe one fine day they will open up their doors, who knows.


Federico, no, currently there's nothing I can point to, unfortunately. jetpad is developed by another team. Regarding our jetpad-based editor, it's work in progress. We're working, stay tuned :) 

Another link: https://datalore.io As far as I know, it's similar to the census analyzer app.

About convenience of projectional editors and tediousness of specifying them, actually one of the focuses of our work in this jetpad-based editor is to let the user get decent editors without having to specify any editing actions at all. Well, as we say in that talk. But of course one has to be able to throw them in, where needed.



Regarding forum activity, I tend to think that there're too many questions and few answers... And when the doubts are somewhat more advanced, then it's almost certain that no answer will appear. Maybe JetBrains could have someone that could actively monitor this forum and try to answer (or try to, internally, find someone who could answer it).

The UI got cleaner, but I miss the tagging (although it was a little confusing when trying to add more than one tag and/or tags with more that one word).

By the way, the forum (and it happens on other JetBrains forums) could normalise the voting: for the post itself it shows "+ -", while on comments it shows "- +".




Sérgio Ribeiro

Porto - Portugal



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