Friday, August 28, 2015

Why the semantic level?

For some reason I seem to have gotten off onto a philosophical tangent while walking the dog this evening, with the resulting epiphany: programming is a process of comprehension. And then documentation of that comprehension.

Back in the day, I spent several years working on two large systems (and here and there some other stuff, but the bulk of my programming work was on two systems). The first was a pharmaceutical document management system, and the second was a searchable online machine tool database. The first was for a corporate gig, obviously - pharmaceuticals are not something done in the garage by a startup - and so it was relatively well-managed and the technical debt was relatively well controlled.

The second was a startup, I was the technical lead and entire staff, and over the course of some dozen years I managed to run up a significant technical debt. Due to that debt, working on the system became an increasingly painful chore (every attempt to address one issue simply reminded me of the dozen related issues that were not going to be fixed because the customer had a very limited budget).

The process of leaving that situation and moving to technical translation took many years, and something in me fought it every step of the way. It was the last paid programming I ever did. Since that time, I've been a hanger-on in the startup programming community, but nothing ever gets off the ground, essentially because I have a fear of technical debt.

But why do we have technical debt? I'll tell you: because we commit to specific platforms and solutions during the programming process, and it is very difficult to undo those early decisions later. By programming at the syntactic level (some of which is of course unavoidable) we lock ourselves into low-level structure we can't easily back out of.

Addressing things at the semantic level - were it possible with existing tools - would avoid at least some of that technical debt. If we have semantic structure - if we are defining not software but the concepts behind the software - then the programming itself starts to look more like a compilation process. And just as we can recompile most code onto a new platform (maybe after fiddling with some flags and libraries), we could back out of syntactic-level, stack-level decisions by "recompiling" a set of concepts on a new platform.

Indeed, in a sense a new set of requirements would be a sort of recompilation.

It's a vague ideal, but this is essentially what I see as the promise of semantic-level programming. I earnestly hope I'll be able to make some forward progress on this over the next year.

Saturday, August 22, 2015

Literate programming: contemplative versus exploratory programming styles

A couple of days ago, HN was asked, "Why did literate programming not catch on?" Predictably, answers ranged from "Because it's useless for real requirements" to "What do you mean? We use it all the time by policy." But a rough synthesis of the overall sense of the meeting, as it were, led me to consider that literate programming requires contemplation. And sometimes you just don't have the time, or sufficient knowledge, to contemplate.

In the typical startup environment, code is written quickly to address specific needs, and as the business pivots and refines, it mutates quickly. So many of the responses addressed that: literate styles don't react well to code churn, and you end up with a literate explanation of code that no longer matches the code (which is of course always the objection to documentation of any kind).

Reading actual code to determine its purpose is effectively reverse engineering. Sure, well-written code should be readable and so it feels odd to call that reverse engineering - but so much real-world code is unreadable that I think it's a good default attitude.

Ultimately, the exegetical stance of integrating literate programming with reverse engineering should support a pretty good overall software development style: quick prototypes to sound out a new task, followed by contemplation of lessons learned and a literate presentation of useful tooling. That's the goal.

Tic-tac-toe and the minimax algorithm: playing imperfect players

I saw an interesting here's-how-it-works post about the minimax algorithm in the context of Tic Tac Toe. I wrote a tic-tac-toe player myself a few years ago, for a HackerRank puzzle, and of course back in the Dark Ages when I was doing my MS in Computer Science.  But in this particular post, Jason Fox makes an interesting point: a perfect tic-tac-toe strategy is fatalistic.

While testing his player, he noticed that once the bot saw it couldn't win, it didn't seem to care how long it took to lose. He modified his algorithm to prefer longer fights, just to make it seem like it was putting up a fight.

Why would this behavior occur? And why does it bother us? Turns out it's simple: a perfect strategy assumes that its opponent is playing a perfect strategy as well, because that's easier to code. In other words, when scoring the different options, the perfect minimax strategy assigns its values by playing the other side perfectly as well. Mathematically, it doesn't matter whether we lose perfectly earlier or lose perfectly later, does it?

But that glosses over a fundamental truth out here in the world, and it's why it rankles to see this algorithm playing so oddly - when playing actual games, it's not at all uncommon for our opponent to screw up. And the longer we draw out the game, the more likely it is that they will. So intuitively, we want to fight a delaying action, because our own internal algorithms tell us that the longer we're in the game, the better off we are in terms of an eventual surprise win.

To reflect that, the tic-tac-toe minimax algorithm should really be modified to reflect the probability of error on the part of the opponent. Even a small change in that score should serve to weight longer fights a little higher, and that's enough for the algorithm to choose that path.

It would be instructive to write that up as a real article, but man, I've got stuff to do that's higher priority than that.

Thursday, August 20, 2015

I've been busy

I see I haven't posted here since March...  Partly because I've been busy, but also because increasingly I find myself wanting to do something real instead of just posting a gallery of things others are doing. And since I'm slowly making some progress on that end - the third go at Decl is starting to come together into something that makes some sense - I think my brain cycles are going there instead of here.

That said, I have a ridiculous queue of interesting things to note. But new rules. I think I'm not going to post unless I have something to say. Which really shouldn't be a problem, should it? I've always got plenty to say.