Today I discovered the following message on my proposal:

This proposal is on hold as a possible duplicate / merge candidate, pending further discussion on meta.stackoverflow.com.

Why is this? This is not a duplicate of any other proposal (as far as I can tell). I realize that some of the proposals on Area51 are duplicates and need to be dealt with - but this doesn't seem to be.

"It belongs on StackOverflow."

Really? Do theoretical questions belong on StackOverflow? Is there a large crowd of compiler designers answering questions on StackOverflow? Are there a lot of compiler design questions on StackOverflow?

This brings to mind the recent "Merge Unix SE / Ubuntu SE" poll we had. The community decided that Ubuntu had enough of a following on its own as to warrant its own site. (Not to mention that many would not be on the site if it were merged.)

Can we please let a proposal with > 160 committed people take the same path that the rest of the proposals have taken? If it fails then we can look at alternatives / merging.

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    I strongly believe that compiler design incorporates sufficient theory that it is the wrong fit for SO. It incorporates sufficient practice that it is the wrong fit for CSTheory. Sep 28, 2010 at 22:41
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    Nooooooo! Closed. Oct 1, 2010 at 16:30
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    I'm at least as sorry as you are. I had high hopes for compiler design.se
    – blucz
    Oct 1, 2010 at 21:17
  • @blucz: Ya, it's quite sad. Oct 1, 2010 at 22:04
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    Attention everyone: there is now somewhere to go to get your compiler design questions answered: Compiler-Design.com. Oct 9, 2010 at 23:33
  • @Paul Nathan: That's why I considered compilers to be the hardest computer courses I ever took. The others typically required either hard theory or lots of programming, not both. Oct 11, 2010 at 13:44
  • @George Edison: When I follow the link you give to super-secret-private-beta.compiler-design.com it has a Google 404 error. And the URL as stated Compiler-Design.com tells me "We're sorry, the site has been taken offline permanently". Jul 30, 2011 at 21:13
  • @hippie: Yeah, it closed down due to lack of interest. Jul 31, 2011 at 3:25
  • Hmm so it was interesting as an SE but not as a separate site? Has interest increased in compiler questions on SO in the time since all this happened? Jul 31, 2011 at 8:38
  • @hip: I really have no idea. Jul 31, 2011 at 19:48

5 Answers 5


To everyone that was disappointed by having the rug pulled out from under compilers.stackexchange.com, I’ve got some good news. A small group of us has banded together to create the website instead, and we’ve started a private beta. By private, of course, I mean only people who have heard of it will be able to access it. The website is currently at the heavily-hyphenated subdomain http://super-secret-private-beta.compiler-design.com/ – and all who committed or were interested in the original proposal are welcome to join. For more details see http://www.compiler-design.com/why .

  • Of those two URLs only the "why" page currently exists. Jul 30, 2011 at 22:06
  • Nope, both dead. Feb 15, 2013 at 13:12
  • @BartekBanachewicz THe site was dead, and thus there was no reason to keep the domain running. Feb 16, 2013 at 13:54

Here's the problem with merging it into the main SO: the SO community doesn't know jack about programming languages. Look at the current latest questions tagged "programming-languages":

I understand the fear of Balkanization, but for specialized domains there's real value in subsetting the community to increase the signal-to-noise ratio. You could argue that game dev didn't need its own Stack Exchange, but the quality of answers to programming questions there is distinctly higher than they were when it was just game-dev tagged questions on SO.

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    Yup. This decision basically amounts to "we don't care enough about this topic to create a venue wherein it can be discussed productively". It's very disappointing.
    – blucz
    Oct 1, 2010 at 23:11
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    I find it especially sad that the proposal was closed with a link to the "compiler" tag. If you look at the 50 latest questions in that tag, you'll see maybe 6 question that are somehow related to compiler design (one of which is closed - though for good reason). All the others are about how to use a compiler, how to get rid of compile errors or how to write programs in a compiled language.
    – sepp2k
    Oct 2, 2010 at 8:20

Neither Stack Overflow nor CSTheory constitute an expert community on the topic of compiler design. On the other hand, Stack Overflow does constitute an expert community on many of the others--regex, android development, iphone development, etc.

Some questions applicable to compiler design do belong in cstheory (help! having difficulty with progress/preservation proof for language feature X), and some questions do belong in SO (help! having trouble with ANTLR). By and large, neither of these sites has become or seems poised to become a venue for serious compiler design discussion.

Why StackOverflow isn't an appropriate venue

StackOverflow is a boring place for people interested in compiler design. These people put in their 10,000 hours of coding a long, long time ago, and became bored of helping people out with the basics years ago. They're not trying to learn API or figure out why their program is crashing. People like this are not going to congregate in a venue wherein every third question is "debug my NullReferenceException for me, please".

Furthermore, searching for a few key compiler-design phrases (like "inline cache" and "baker's treadmill") on StackOverflow turned up nothing--StackOverflow is not already functioning as a compiler design community and has failed to build a meaningful compiler design knowledge base. If StackOverflow were going to meet this need, it would have done it already. It clearly hasn't.

StackOverflow is about short-lived questions--questions come and are answered very quickly. This is a poor model for design discussions on complex topics.

Why CSTheory isn't an appropriate venue

If you've designed compilers and spent much time over at CSTheory, it will be clear to you that questions about inline caching and garbage collector design do not belong next to questions about bounds 3SAT and hamiltonian tours. CSTheory is a discrete math forum, and its proponents would be happier if it stayed that way.

But a discussion about approaches to real-time garbage collection? An in-depth discussion of stack vs. register architecture for your virtual machine? StackOverflow tends to shy away from vague questions like this, and CSTheory would just close them as irrelevant, as they do any question that even has a hint of concern for implementation.

Compiler Design is, in principle, a lot like CSTheory

CSTheory is, unlike StackOverflow, a community of experts participating for the benefit of other experts and the field as a whole. In contrast, StackOverflow has some experts (the most prolific of whom are authors/educators first and implementors second), a ton of middle-of the road people, and a huger ton of flat-out newbies, and it's about answering questions that come up while writing code quickly in return for reputation.

CSTheory has a high barrier for entry--anyone without serious theoretical CS/discrete math background is going to find most of the discussion to be over their head. This is a good thing for them. The community that exists around this topic requires that condition to operate efficiently, and they've built it for themselves.

The compiler design stackexchange should be similar in character to CSTheory--a community of experts familiar with the latest in the theory and practice of compiler design addressing the gray areas and discussing the latest research together. Like CSTheory, compiler design should be a place for long-lived questions with many contributors and less emphasis on reputation farming.

In summary

Please don't kill the Compiler Design StackExchange--the compiler design community sorely needs a place like this to congregate and have high-quality discussions without being subjected to the SnR of SO or the strict "no implementation questions" attitude of CSTheory. Much like CSTheory, in order to attract the experts of the field, a more exclusive venue must be created.


The top brass seem to have gotten the idea into their heads that any subject that's even sort of related to programming should be merged into Stack Overflow or Programmers.SE. Compiler Design is actually at the top of Jeff's short list.

The full list of Stack Overflow "merge" candidates is:

  • Compiler Design
  • Artificial Intelligence
  • Machine Learning
  • Android Developers
  • Databases
  • Webservice APIs
  • iPhone Development
  • Operating Systems Development
  • Regex
  • Genexus
  • JetBrains ReSharper
  • Natural Language Processing and Computational Linguistics

I think it's ridiculous to suggest that compiler design or OS development or even web service APIs can be reasonably discussed on Stack Overflow without either getting buried or accumulating enormous amounts of noise, but there you have it. Once they get an idea like this into their heads, it takes a lot of convincing to dig it back out.

(But who knows - maybe they're right and all of us are wrong?)

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    you linked to the wrong blog entry Sep 28, 2010 at 22:42
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    AI, NLP, Machine Learning should probably be rolled together. iPhone devs and Android devs should probably be on SO. OS dev, not sure. Depends on how much scheduling theory/RTOS theory it really needs. Database design is not really SO's forte either. (I don't mean SQL hacking, I mean large-scale design and DBA). Regex probably should be on SO too. Sep 28, 2010 at 22:44
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    @Aarobot Some people do agree with management on this one. Volume matters.
    – C. Ross
    Sep 28, 2010 at 22:48
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    @Jeff - your link text ("wrong blog entry") was to the right blog entry, not the wrong one. Now I'm confused.
    – user27414
    Sep 28, 2010 at 22:53
  • CRoss: I'm sure that they do, there have already been a few discussions about it on MSO with some highly-voted "I agree" answers. I wasn't meaning to suggest that all of us disagree, only that many of us do.
    – Aarobot
    Sep 28, 2010 at 23:19
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    NLP has landed inside the stats site. (shhhh)
    – Rosinante
    Sep 29, 2010 at 1:18
  • The biggest problem for the separate sites will be gaining critical mass. SO's biggest benefit is the huge community. In general, the SE sites' biggest liability is the lack of critical mass. The secondary issue is fragmentation of attention; if someone is active on an SE site, they can't be as active elsewhere. Oct 1, 2010 at 23:26
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    @Jonathan: This has been brought up before. With highly specialized topics, many if not most participants would rather the community be smaller and at a high level. And as for fragmentation, most of those people have already given up on Stack Overflow - too much noise.
    – Aarobot
    Oct 2, 2010 at 2:45
  • The problem with noise on Stack Overflow would be much reduced if there were decent filtering options, instead of just the lousy favourite/ignored tags system. Oct 5, 2010 at 1:13

I don't see a a theoretical/practical analysis of (say) LL vs. LR parsing being the correct fit for SO.

It's not really programming related in the sense of "Question about Language or API" (which it seems the majority of SO questions are); it's fairly theoretical, even if it does fall out into code in the end.

  • I fail to see why a question about the practical implementation of a compiler wouldn't fit on SO, opinions about compiler tech on programmers, and theoretical discussion on cstheory. Sep 28, 2010 at 23:00
  • @Kevin: That's not the point. The point is that I believe the community would be better served if it had its own site. Sep 28, 2010 at 23:03
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    @Kevin: Ask three questions on three sites just for one original question? You've got to be joking. Sep 28, 2010 at 23:06
  • @Paul - what questions are you going to ask that have a practical, theoretical, and opinion component? You've got to be joking. Sep 28, 2010 at 23:12
  • @Kevin: I guarantee you interesting questions have all 3 of those components. Sep 28, 2010 at 23:14
  • @Kevin: Paul is right. Some questions will have all 3. I have designed a compiler. It's very likely that such a question will be asked. Sep 28, 2010 at 23:17
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    @George - posit one. I too have designed a compiler, its standard CS degree material, the questions I had could have been broken up appropriately. Sep 28, 2010 at 23:25
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    @Kevin: Regardless, I think if the community wants the site, you should at least give it a chance - the commit numbers show a pretty significant interest. The goal is to create sites that sustain a lot of traffic, right? Sep 28, 2010 at 23:31
  • @George - still waiting for that example question. Looking at the proposal, at least 4 of the top 5 are subjective (by SO-criteria). Not promising. Sep 29, 2010 at 0:01
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    @George, 170 committed is not really that much for that argument -- you should try to get more.
    – juan
    Sep 29, 2010 at 0:17
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    I committed to it, but warily; in my humblest of opinions, any objective compiler design question can be asked on Stack Overflow. I mean, a compiler design question is about a programming-related as you can get. I don't really understand why people think a [compiler-design] tag on Stack Overflow wouldn't be sufficient. Sep 29, 2010 at 0:50
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    @George: Ok, and there are 2,000 questions tagged [compilers]. While I'm sure not all of those are compiler-design related, quite a few of them are. If the problem is categorization, then that's easy to solve (retag questions!). If the problem is that people don't have questions about compiler design, I don't see how adding yet another site is going to fix that. Sep 29, 2010 at 2:02
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    @James: I understand what you're saying, but I can certainly speak from my own experience. I have compiler design questions that I'm purposely not asking on StackOverflow. Why? I'm waiting to ask them on the Compiler Design site because that's where they'll receive attention. You also forget that asking those questions on StackOverflow results in useless answers like this one. They'll be no chance of confusion on a dedicated site. Sep 29, 2010 at 3:31
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    @Kevin: My estimation is that if I take a highly technical modern compiler question (which is essentially a CS theory question), then there are maybe 5-10 people on SO who are liable to answer and have the knowledge to give a real answer. Now, maybe SO management is okay with that. But my hope is that Compiler Design would be a Stackexchange that could mix the theoretical and the practical. Sep 29, 2010 at 4:27
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    @Kevin: Because a careful discussion of - say - abstract interpretation and different properties to smartly infer an analysis and then to go out and implement that is not appropriate for SO or CSTheory. Look at Lambda the Ultimate. That's theory, but it all falls out into actual code. Sep 29, 2010 at 4:56

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