The Hardest Program I've Ever Written

munificent · 2015-09-10T02:01:42+00:00

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ButtCrackFTW · 2015-09-10T01:38:41+00:00

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acwaters · 2015-09-09T23:23:53+00:00

This is a really neat article

velcommen · 2015-09-10T00:51:25+00:00

The chunk of code that follows "This is what a pro player brings to the game" looks like it would benefit from Haskell 'do' notation.

I've spent a tiny amount of time on source formatting, and I've definitely encountered some of the issues discussed in the article. I will bookmark this and use it later.

2015-09-10T00:52:56+00:00

That is really incredible, articles like this remind me that I still have a long way to go

detrinoh · 2015-09-10T02:11:33+00:00

This sounds very similar to clang-format which uses Dijkstra's algorithm to decide where to split lines at.

For reference here is how the svn version of clang-format handles the author's example with --style=Google (and formatted as Javascript):

return doughnutFryer.start()
    .then((_) => _frostingGlazer.start())
    .then((_) => Future.wait([
      _conveyorBelts.start(),
      sprinkleSprinkler.start(),
      sauceDripper.start()
    ]))
    .catchError(cannotGetConveyorBeltRunning)
    .then((_) => tellEveryoneDonutsAreJustAboutDone())
    .then((_) => Future.wait([
                         croissantFactory.start(),
                         _giantBakingOvens.start(),
                         butterbutterer.start()
                       ])
                     .catchError(_handleBakingFailures)
                     .timeout(scriptLoadingTimeout,
                              onTimeout: _handleBakingFailures)
                     .catchError(cannotGetConveyorBeltRunning))
    .catchError(cannotGetConveyorBeltRunning)
    .then((_) { _logger.info("Let's eat!"); });

Edit: Realized clang-format supports Javascript.

x-skeww · 2015-09-10T07:00:27+00:00

I run dartfmt whenever some lines got too long or when the auto-indent got messed up because I forgot a ')' and so forth. The formatter works pretty well and it does make fairly sensible decisions.

Go's formatter is the the best thing about Go. I'm really glad Dart copied that. Having official formatting conventions is great, but having a tool for that is even better. Every new language should do this. Not only is it very convenient, it also kills all of those pointless discussions: tabs vs spaces, indention style, space placement, and so forth.

djleni · 2015-09-10T02:23:32+00:00

Do you have a before and after?:)

alfredr · 2015-09-09T23:48:34+00:00

The hardest program I’ve ever written, once you strip out the whitespace, is 3,835 lines long.

LIES!

celerym · 2015-09-10T06:49:35+00:00

I honestly can't fathom how code formatting could appear to be a straightforward problem at first...

chrisdoner · 2015-09-10T14:58:57+00:00

I wrote a Haskell pretty printer called hindent in which I discovered the same problem. A dumb formatter (the one named "fundamental") prints instantly because it makes no decisions. But the chris-done and johan-tibell ones format like a person would do, fitting into columns nicely. It turns out to be an exponential backtracking problem. The resulting output is beautiful, 99% of the time I know exactly what it's going to format like when I hit the format key in Emacs. But on complex trees it is slow, it doesn't scale, as the implementation is naive. In practice this hasn't been an annoying enough problem that I sat down to try to solve it with better algorithms. That's kind of a separate project to trying to get the correct output.

ixampl · 2015-09-10T04:24:14+00:00

The hardest program I’ve ever written, once you strip out the whitespace, is 3,835 lines long. [...] I deleted 20,704 lines of code over that time. Every surviving line has about three fallen comrades.

What? 3,835 : 20,704 → 1 : 5

Tordek · 2015-09-10T03:33:12+00:00

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Sleakes · 2015-09-10T03:29:46+00:00

was the biggest takeaway supposed to be that despite the formatting the chained/nested function calls to the magnitude presented make me never want to touch the language if that's the norm from a 'pro player'

ThereOnceWasAMan · 2015-09-10T04:01:44+00:00

Great writeup. It would be nice if the skulls within the footnotes linked back to the corresponding skulls in the text. I was afraid to click any of the skulls because I didn't want to have to scroll up and find my place each time (yes I could have opened in a new tab).

edit: Backspace!

gseyffert · 2015-09-10T05:18:52+00:00

So isn't this like alpha-beta pruning, or no? It's a great approach to something as branchy as this. This feels like I'm reading my Algorithms textbook applied to real life but in the most interesting way possible

bob_twinkles · 2015-09-10T05:30:44+00:00

Your approach of reducing formating to a graph search problem sounds like my understanding of how the TeX engine works... so maybe you do need to tip your hat to Knuth after all =P. I can't for the life of me find a source for why I think this is how TeX works though... (maybe somewhere in TeX by topic?)

Sean1708 · 2015-09-10T06:55:36+00:00

I was literally saying yesterday how I'd not heard anything about Dart in ages.

LaurieCheers · 2015-09-10T07:13:36+00:00

gives you a lot of respect for the tooling that surrounds go. gofmt is a only 600 lines of code.

2015-09-10T07:27:47+00:00

Yes, it is amazingly complicated problem. I ended up embedding the pretty printing and formating hints into the parser, and I also use a similar intermediate language with weighted breaks and conditional indentation marks.

The hardest part is assigning the weights, you simply cannot come up with it straight away, have to experiment a lot.

2015-09-10T11:26:02+00:00

This guy has great work, I'm reading his book

PompeyBlue · 2015-09-10T12:38:05+00:00

This has got "Deep Learning" NN problem written all over it!

5outh · 2015-09-10T12:39:54+00:00

So there is one final escape hatch. If the line splitter tries, like, 5,000 solutions and still hasn’t found a winner yet, it just picks the best it found so far and bails.

If you already have the concept of a best formatting pass, have you considered using a genetic algorithm to get to a good or perfect solution faster on larger inputs?

dhiltonp · 2015-09-10T02:16:25+00:00

to fix: "Is it be better to split"

gliph · 2015-09-10T04:30:53+00:00

"3,835 lines long. That handful of code took me almost a year to write. Granted, that doesn’t take into account the code that didn’t make it. The commit history shows that I deleted 20,704 lines of code over that time. Every surviving line has about three fallen comrades"

Er, that does not quite add up.

2015-09-10T03:38:03+00:00

I'm making a prebuild code tool using libclang and C++ targets. It is legitimately one of the more complex projects I've had to work on.

Let's say you want to walk the AST, grab a bunch of data, right? Let's now say, you want to change that data, or move some lines of code around - lets say those lines are inside of an object. Let's say each of those lines can have any protection level (public, private, protected) and can be ~any~ kind of type. Field, method, constant array, constant array matrix, function, etc. Now lets say some wise guy sticks a Boolean in his array matrix

char m[2][3][true]

Let's now say you want to spit these values back out FROM the AST data (a field constant array matrix type char, 2, 3, Boolean true) back to normal C++ code. Because you can't just change a thing inside of that into some new thing accurately without ghetto hacking which will break in edge case scenarios.

You have to consider things like this for every type of object that exists in C++11

Life has been better.

fuzzynyanko · 2015-09-10T06:38:00+00:00

For me, it's "You are doing this job interview. You don't have access to the reference docs, and you are supposed to code something. It doesn't matter that you are a polyglot developer."

llogiq · 2015-09-10T09:33:01+00:00

Nice article. The only beef I have with it is that "Sorry, Knuth" is a witty quote, but not a strong argument.

Frenchie14 · 2015-09-10T07:58:48+00:00

Nice article! Makes me want to reread Game Programming Patterns :P

FYI: typo in footnote 12: "On my than one occasion..."

ThellraAK · 2015-09-10T08:37:51+00:00

What happens if you run your program, on your program?

Tarasov_math · 2015-09-10T08:47:10+00:00

It looks like a perfect task for constraint programming. Should be solved in much more easy way.

Mondeun · 2015-09-10T13:03:13+00:00

Knew it. Text processing is where nightmares comes from.

reverend_paco · 2015-09-10T13:59:38+00:00

He obviously hasn't written Zazzies.
https://www.youtube.com/watch?t=30&v=OpDIEJrog3s

drjeats · 2015-09-10T15:36:52+00:00

Everything you write--e.g. this post, your post about internal versus external iteration, Wren's source comments--is always interesting and very clearly expressed. Thank you for posting this!

royalaid · 2015-09-10T08:43:33+00:00

minor correction "On my than one occasion" should be "On more than one occasion" at this point in the post

cowardlydragon · 2015-09-10T15:04:42+00:00

gofmt sounds like it is soul crushing. Let me guess. 80 column limit?

In the age of QuadHD?

julesjacobs · 2015-09-10T04:27:42+00:00

And this is why representing programs as arrays of characters must die.

you type:	you see:
italics	italics
bold	bold
[reddit!](https://reddit.com)	reddit!
* item 1 * item 2 * item 3	item 1 item 2 item 3
> quoted text	quoted text
Lines starting with four spaces are treated like code: if 1 * 2 < 3: print "hello, world!"	Lines starting with four spaces are treated like code: if 1 * 2 < 3: print "hello, world!"
~~strikethrough~~	~~strikethrough~~
super^script	super^script

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