Oslo

Radio Silence

Paul Vick — Wed, 04 Nov 2009 19:21:17 GMT

Gosh, it’s been six months since I’ve said anything on this blog. I was beginning to wonder myself whether I’d ever come back or if this just would become yet another decaying corner of the Internet… Anyway, things have been quiet around here for several reasons.

First, there’s just been a lot going on in my world, and blogging (and tweeting and facebooking) has been pretty low on the priority list. None of it is worth broadcasting to the entire world on the Internet, but suffice it to say that it’s been a very heavy year.

Second, I finally realized I really needed a break after ten years slugging it out on VB. I knew I was burned out when I changed jobs, but I don’t think I knew how burned out I really was. The last year has been very therapeutic in that I’ve mostly just kept my head down, showed up at work, and did the work of the average developer—write code, fix bugs, etc. That’s been great, and I had forgotten how much fun it is to just… write code. It’s not the only thing I want to do in my life, but it’s been very nice after the roller coaster of 3.5 major versions of VB to just show up, do my job, and go home. I think I’m now starting to look beyond that, but there you are…

And, finally, I do try to live by the maxim that “if you don’t have anything to say, don’t say it.” Working on M has been fun, but it became clear to me around the time of my last blog post just how much I didn’t know about what I was talking about. (In fact, I owe several corrections on my previous blog post, which I’m working on.) That’s been OK, though, since clearly my team has also gone through several rounds of figuring out what we’re doing, too. It does feel like we’re reaching one of those inflection points where things are about to get a whole lot more clear about M, which is great and maybe means I’ll have more to talk about.

So, yes, I’m still alive. We’ll see how much I have to say.

(By the way, sadly, I won’t be at PDC this year, so have fun without me!)

“Oslo” has a May 2009 CTP…

Paul Vick — Fri, 29 May 2009 17:11:04 GMT

In case you missed it, we pushed out a new CTP this week of “Oslo”. You can get it at the Oslo Developer Center. New stuff includes:

The "Quadrant" modeling tool. Use Quadrant to browse and edit models in a repository database.
Domain models for the UML 2.1 specification encompassing Use Case, Activity, Class, Sequence, Component diagrams, profiles and templates.
An XMI importer supporting the 2.1 specifications, and covering the diagrams identified above.
A domain model and loader for System.Runtime.

There isn’t a huge amount of change for the language portion of M in this CTP. Most of the major differences are under the hood and will only be apparent if you’re calling the underlying APIs directly. The only big thing I can think of is that the “identifier” keyword is no longer needed in a grammar—we’ll automatically detect the situation for you.

The feature I spent most of our last milestone working on appears to be finally coming together, so I hope to have more to say about that soon.

Catching up on free media

Paul Vick — Mon, 11 May 2009 22:36:53 GMT

Things have been a bit quiet around Panopticon Central lately due to the fact that I’ve been heads down on developing a particularly gnarly feature in M. More on that if and when it starts to see the light of day. But in the mean time, there have been a few interviews/talks that have been posted that I wanted to point out:

I did a Code Cast interview with Ken Levy in which I talked about M, VB and apparently gave out the wrong address for this blog!
I gave a talk with David Langworthy at Lang .Net 2009 on “Oslo”: Modeling in Text.
I gave a solo talk at DSL DevCon on “M” DSLs: Deep Dive.

Hope you enjoy them!

“M” at Mix09…

Paul Vick — Tue, 17 Feb 2009 00:35:02 GMT

Another “in case you missed it,” there’ll be some new information about “M” revealed at Mix09. More details on Doug’s blog…

Lexing and Parsing

Paul Vick — Thu, 12 Feb 2009 19:30:08 GMT

I want to talk in more detail about how the MGrammar parser works, but before I delve too deeply in to that I wanted to talk a little bit about some basic parsing concepts so we can be sure we’re on the same page. This may be a bit basic for some, so you can just skip ahead if you already know all this.

A language grammar is actually made up of two different grammars: a lexical grammar and a syntatic grammar. Although a grammar may not distinguish between the two in its specification (as we’ll see later), every grammar has these two things contained within it. The lexical grammar translates characters (the raw material of language) into lexical units called tokens. The syntatic grammar then translates the tokens into syntatic structures called syntax trees.

Let’s take a look at this in practical terms. Let’s say you’ve got the following sentence:

Alice kissed Bob.

Fundamentally, this sentence is just a collection of characters: the upper-case letter A, the lower-case letter l, the lower-case letter i, and so on. Lexically analyzing this string takes these characters and shape them into the basic tokens of English: punctuation and words. So a lexical analysis might return the following tokens: the word Alice, the word kissed, the word Bob, and a period.

One thing to notice here is what’s missing in the list of tokens—every character in the string “Alice kissed Bob.” is represented in the token list except for two characters. We’ve dropped the spaces between the words out of the token list, and we’ve done this because spaces aren’t significant in English syntax. (As anyone who was taught to type two spaces after a period can attest.) In other words, you can have as many spaces as you want between tokens and they don’t mean anything except as delimiters between tokens. In other words, “AlicekissedBob.” is not the same as “Alice kissed Bob.” but “Alice kissed Bob.” is the same as “Alice kissed Bob.” (Although it looks a little funny.) Since spaces don’t matter once we’ve formed the tokens, we toss them out.

Once we’ve got the tokens, we can then proceed to do the syntatic analysis. In the case of English, a common syntax pattern is “<subject> <verb> <direct object>.” Looking at the sentence, we can pretty easily discern this pattern at work: the subject of the sentence is “Alice,” the verb is “kissed,” the direct object is “Bob,” and the sentence ends with a period. Since the verb links the subject and the direct object, we’d probably come up with a syntax tree that looks something like this:

As I said before, some languages make a bigger deal of lexical vs. syntatic grammars than others. For example, if you go and read the XML spec, you’ll see that they don’t really call out what’s a token and what’s syntax. On the other hand, the Visual Basic language specification is extremely explicit about the distinction between tokens and syntax, even going so far as to have two separate grammars. How you think about tokens vs. syntax has big implications for the implementation of your parser, which I’ll talk about in my next entry…

In case you missed it… Oslo CTP2 is out.

Paul Vick — Wed, 11 Feb 2009 01:17:16 GMT

You can get it here.

MGrammar and Rescuing the Princess

Paul Vick — Sat, 13 Dec 2008 00:22:58 GMT

One of the major reasons that I decided to come to work on the Oslo team was the experience I had with what was going to become MGrammar. I was interested in prototyping some language and compiler design ideas, and I knew that the Oslo team had some technologies that might help me out, specifically a parser generator. They helpfully pointed me to their source code, I enlisted, built and started to play around. I’d been building some parser technology by hand, but I quickly discarded it once I started playing around with MGrammar in Intellipad. In addition to giving me a bunch of things that I needed, it was also just really… fun. I mean, it was cool to bring up a buffer, start hammering on a syntax and then put in an example and see the result pop up. Or, as was the case most of the time, not pop up. Tweak, tweak, tweak and then… boom! the result shows up.

This storyline is one that I’ve heard a number of times internally and even seen externally a time or two. People just have a great time playing around with grammars and languages and seeing what they can get to come out. There’s frustration, sure, but then there’s also a big payoff when you finally see it working—look what I created!

I hadn’t really thought a lot about it until I came across a presentation that Daniel Cook (author of the Lost Garden blog) gave at an OfficeLabs meeting entitled “Mixing Games and Applications.” He says it a lot better than I can, but I intuitively think that I (and others) enjoy fooling around with MGrammar in Intellipad precisely because it taps in to game playing part of our brain. I’m not sure how to capitalize on that further, but it’s interesting food for thought…

Answering some questions about MGrammar….

Paul Vick — Fri, 12 Dec 2008 22:43:01 GMT

As some readers have noticed, I’ve been conspicuously silent since I moved over to the Oslo team. Some of this had to do with getting onto a new blogging engine, some of it had to do with various distractions like jury duty, but a lot of it had to do with the fact that Visual Basic 10.0 has gotten to a pretty stable state (so there isn’t so much for me to say any more) and I am just getting off the ground with Oslo. Not having much useful to say, I figured I’d be better off saying nothing at all rather than continuing to blather on and on about nothing in particular (that’s what Twitter is for).

Part of the process of moving over to Oslo was figuring out exactly what my role was going to be. There’s lots of cool stuff going on and a lot of smart people with strong ideas about things, so I knew it would take a while for things to settle out. Things will still probably evolve over time, but the area I’ve spent the most time on, and the thing I’ll have the most influence on for the time being, is MGrammar. It’s been an interesting experience because I’ve had to relearn a bunch of the theory around parser generation that I had forgotten in my time in VB (since we had a hand-built recursive descent parser). But it’s been enjoyable, and I think there are a lot of neat things we can do with it. So stay tuned on that.

Someone forwarded me Kevin Moore’s 20 questions/thoughts around MGrammar, and I thought answering some of those questions might be a good entree into blogging about my new job. I won’t address all of his questions, but the interesting ones, in my opinion, were:

Could C#/VB implement their compilers using MGrammar? Should they? Would they?

I believe that, as the languages stand today, C# could implement their parser using MGrammar but VB couldn’t. The reason why VB couldn’t is a pretty technical issue relating to the embedding of XML into VB which we may end up solving as well, but given the hacks that we (VB) had to do to the hand generated parser to get it to work I don’t think that reflects badly on MGrammar (or VB for that matter). The bottom line is that the parser generator is certainly powerful enough to handle an industrial-strength language. Whether the C# or VB teams should or will do anything with MGrammar is really a question for them. Both languages have hand-built parsers which allows an extraordinary degree of control over the behavior of a parse and, in particular, error messages and error recovery. They may be loath to give that up, but we’ll see.

Where is the MGrammar for C#? …for VB? …for CSV? …for VS solution files? …for XML?

In general, the Oslo team is just one little team and can only do so much. Although we endeavor to provide you with the maximum number of samples, in truth we are limited in what we can do at any one time. You should expect to see more samples as time goes on. I’ll also note, though, that some of those languages do present interesting challenges to a parser generator. I’ve already covered VB, but XML also has challenges, which I think is really a subject for another entry.

There should be standardized or defacto escape mechanisms for existing grammars.

If I understand the point here correctly, what’s really being asked for is composability of grammars. This is a difficult, but interesting, area of work. To use an example I’ve already referenced, there were a lot of challenges integrating XML into VB because the languages were very different, even down to the lexical level. Having languages compose in some kind of simple way (even to do things like add or override parts of an existing grammar) is an open question that we’re very interested in but we’re still working on.

Will there be tools to go back from a logical model (MSchema) to the input format?

This is on our radar, but we don’t have an answer at the moment. It’s a very natural and logical thing to do, but (of course) running a grammar in reverse is not a trivial matter. I’m not sure we can get to a point where we can reverse a parse automatically, but we do want to provide people with a way to do this in as simple a manner as possible.

Where is the community site for MGrammar?

Well, we’ve got the Oslo Developer Center and the Oslo forums. If you want to start a community site, by all means go ahead!

Any news with Mono? Is Miguel interested?

I think you’d have to ask Miguel that…

Are you making a play to make MGrammar a standard? I’ve heard yes, but just wanted to confirm.

What we’ve committed to is releasing the MGrammar specification (well, actually, the whole M language specification) under the Open Specification Promise. That’s the only commitment we’ve made so far regarding MGrammar’s specification, but it’s a pretty big one.

How is the computer science behind MGrammar?

Pretty good, and I expect it to get even better. Expect to hear more here and elsewhere about internal specifics as time goes on (it’s a little more than can be covered in one blog post).

I hope that answers some questions, and feel free to ask more questions here or on the forums. Thanks!

An embarrassment of riches on VB 10.0 and Oslo

Paul Vick — Fri, 31 Oct 2008 20:11:00 GMT

Now that we’re past the PDC, there are a bunch of video resources coming out on VB 10.0 and Oslo. Here’s a roundup of what’s available so far:

Channel9 has a video that I did with Don and Chris on M called, “Don Box, Paul Vick, and Chris Anderson: Introducing M”
Channel9 also has a video Don and Chris did on their own covering Oslo, “Don and Chris explain Oslo in 5 minutes”

The Pearson folks also recorded some vidcasts they call OnMicrosoft. If you go to the previous link, you can see all the videos posted, but the ones of interest to this blog are:

Lisa and I did one on “Visual Basic 10: New Features”
And also one one “Future Directions of Visual Basic”
Then we moved on to talk in general about “"Oslo" -- Microsoft's Modeling Platform”
And got specific on “The "Oslo" Modeling Language: "M Grammar"”

There are other Oslo vidcasts on the site, so check them out as well.

‘Oslo’ details starting to trickle out…

Paul Vick — Tue, 28 Oct 2008 01:38:00 GMT

The Oslo dev center on MSDN is now up, and the Oslo CTP is available. You can also check out Models Remixed for even more information and keep your eye on the M language blog. More to be revealed tomorrow…