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Comment by CPLX | Hacker News Reader

I wish I was as smart as these people.

These are smart people of course, but it's easy to get overly impressed by these results because all the scaffolding is missing. Behind such a result, there is a lot of tinkering, many leads going into dead ends. By the time you hit a solution, you have in your mind a theory of why it works and you can start cutting it down by removing anything non essential. You end up with a clean result that seems almost magical.

If you know anything about regular expressions, perhaps considering yourself a fairly decent expert... you might even know how to write basic recursive regexes. Then you are like me and think you know how to begin ripping apart any regex.

Then you see "<^<()(?R){2}>\z|\1\Q^<()(?R){2}>\z|\1\Q>", and you can't even begin to parse it. For one, I didn't know you could add a quantifier to a recursive pattern. Then there is a backreference to what appears to be an empty capture, which is part of an alternation for fuck's sake, which also happens to include the \Q notation.

I imagine I am in the top 20-30% of regular expression users. And I straight up do not understand a single aspect of how this expression manages to match anything, let alone its intended purpose.

It doesn't matter how this regex was found. Whether it was obtained through an entirely manual process or assisted by some kind of AI, it's beyond incredible. 99.9999xxx% of senior software developers who have been programming for 30+ years could not come up with this if they were given 10 years to try and discover it out without 3rd party assistance.

>> These are smart people of course, but it's easy to get overly impressed

How bloody arrogant, and frankly a bullshit statement from someone who has no idea what they are talking about. This is amazing. Someone would have to sit down with me for at least a week - probably 3+ months - to even begin to explain to me exactly how this works.

Why did I take this comment so personally? I don't know, it sounds like the parent has never even seen a regular expression, and yet is trying to promote their own sense of worth as if they're a genius when in fact they have an IQ of 40. That somehow the people who managed to figure this out are only lucky to have done so, rather than there being any significant time or skill involved. I bet you there are less than a thousand human beings on Earth who could have solved this. It's likely that the people who fucking designed and wrote PCRE could not have even solved this.

Basically, stfu. Why do you have to comment only to diminish someone else's success story? You couldn't have solved this, so don't even try to minimize the achievements of others.

I didn't read that as trying to diminish the brilliance of the original accomplish, but just trying to frame it less as "magic" or "genius" that is incomprehensible and more as an impressive human feat by a human who had to do hard human work to get there. I believe the intent was to encourage us not to lessen the extent to which we believe that this is something that only a higher class of people can do. Ie: yes, we can't comprehend it on first glance, but they didn't come up with it instantly either. They spend time gradually working and modeling the problem in their head so that the end result is comprehensible to them.

Thank you, that was indeed my intent here. I don't want to take away anything from the achievement, but you explained it better than I did.

     Everybody is a Genius. But if you judge a fish by
     its ability to climb a tree, it will live its whole
     life believing that it is stupid.

     - Albert Einstein

Probably not Einstein http://quoteinvestigator.com/2013/04/06/fish-climb/ (not that it matters in any deep way).

As a non-fish that can't climb trees I find this even more depressing.

"The problem with quotes on the internet is that it can be difficult to verify their authenticity." - Abraham Lincoln

I remember seeing this on Facebook and looking in to it. Turns out some fish do climb trees!

Also no evidence that Einstein said it. Indeed he seems to contradict the general idea behind it.

Not everyone is a genius. Being amazing at woodwork or running is not "genius", it's admirable but different. Some people are [intellectual/intelligent] geniuses, period. Not everyone is.

The best way to take this aphorism IMO is "don't stress out if you're a fish and you're no good at climbing trees, if your thing is swimming that's good too".

I'm inclined to say that some people 'just get' certain things like this or complex SQL. How they got to 'getting it', I don't know.

And monads.

My suspicion is that no one wants to explain monads because if they did it would be painfully obvious that they're a purgatorial way of getting around the basic mismatch between functional purity and actual computers.

Actually, it's the other way around. Monad tutorials are so frequent that it's become a meme among Haskellers that everyone will eventually write a monad tutorial to relay his own mental model of monads.

And as someone who's read what is probably most of those tutorials - I fulfill the other half of the meme.

"To understand monads, you first need to understand monads."

Sorry -- you're right. I should have said "explain monads well."

In Haskell and PureScript, Monad is a typeclass just like any other.

They are an abstraction, effectful computation is not inherent to them, they represent computational contexts, e.g. the list monad is used to model non-determinism, the maybe monad represents computations that can fail, both of these are pure.

This is an excellent set of posts for building an intuition about monads: http://mvanier.livejournal.com/3917.html

> the list monad is used to model non-determinism

See this is the kind of thing that made learning Haskell so hard for me. I'm not a math guy, I'm terrible at math. I have no idea what "non-determinism" means, and I'd venture to guess that list monad is used to model "ordered collections of things".

"non-determinism" implies unordered.

See, to me, the sequence of keypresses I make while banging on my keyboard seem like it could be represented as an ordered list. I may be missing something, though.

If something is unordered it does not mean it may not be ordered. It only says you cannot assume that it is ordered. (A Collection in Java/C# is an unordered contract, but a List is also a Collection.)

But the idea of a list also suggests an ordering to me.

I'm not a math guy either and I did indeed find it difficult to penetrate the inner sanctum of Haskell for this very reason. I won't say I've completely succeeded in that effort, but I've come quite a long way.

I'm fairly certain that in this context, non-determinism means that there can be more than one answer/result.

Scala calls the monad bind "flatMap". Java actually implements it for Streams.

If you have a `Stream<Deck> decks;` of card decks, and want to get all the cards from all the decks, you might try to do something like `decks.map(deck -> deck.getCards().stream())`, but that will give you the type `Stream<Stream<Deck>>`. That sucks, we just want a single stream, not a stream of streams, so we call the function that flattens at the same time. `decks.flatMap(deck -> deck.getCards().stream())`.

Nondeterminism is just a standard use for this construction: given one choice, generate more choices, given that choice, generate more choices, do some computation with the choices, and then return the list of possible final results.

Monads for all your I/O yeah, probably kind of dumb. Monads as a tool for dealing with cross-cutting concerns? Ridiculously useful. http://reasonablypolymorphic.com/blog/ideas-and-men has some basic examples.

Naw, everyone who understands monads wants nothing more then to explain it. Hence the profusion of tutorials and over-focusing on the concept.

For starters, they've probably spent 100 to 1000x more time doing it than you or I have.

Perhaps their talent is actually just an attraction to studying it really hard. I, for instance, do not have the patience to study regex so much as to ever get the point where I could easily answer this question.

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