A curated list of things related to Vue.js - <AUTHOR> https://github.com/vuejs/awesome-vue <comment><USER2> I recently tried out vue.js on a projet as a replacement to d3's selection/data-binding magic. I have to say, I've been impressed.

1\. The API surface is fairly small, especially compared to Angular. I could grok how it worked very fast.

2\. The fact that it works without build tools is a godsend. My project is fairly small, and having as fast an iteration cycle is really nice.

3\. The debug tools are _awesome_. EDIT: [https://github.com/vuejs/vue- devtools](https://github.com/vuejs/vue-devtools)

However, I do have a BIG problem: the fact that mutating the data automatically does a rerender is a nice idea, but in practice it falls apart very quickly and leads to fairly hard-to-debug bugs. For instance, if I add a new field to an object, it will not be detected as a change by Vue and not cause a rerender[0]. In my case, it broke the magic and caused me to look into how the heck did vue actually work - only to find out I had to call this.$forceUpdate() in a few places. It's terrible.

React, despite its problems, is nice because of exactly this : its data binding is entirely non-magical. You have to go through setState _or_ force an update. The mental model is dead simple. I wish I could like vue more...

[0] It is somewhat documented here: [https://vuejs.org/v2/guide/instance.html#Data-and- Methods](https://vuejs.org/v2/guide/instance.html#Data-and-Methods) among other places

<comment><USER3> Why not just add your property with "vue.set()"?

I feel you could have avoided this "awful" pain by just reading a little documentation.

I mean, how exactly did you think your new property would be picked up? I know frameworks are supposed to abstract over things but you do still need _some_ idea what's happening under the hood.

<comment><USER4> Vue.set is the way to go here, which used to be more prominent in the docs. The section that called this out (along with other reactivity "gotchas") has apparently been removed from the latest version.

Here's an archive link: [http://web.archive.org/web/20170711045330/https://vuejs.org/...](http://web.archive.org/web/20170711045330/https://vuejs.org/v2/guide/reactivity.html#Change- Detection-Caveats)

<comment><USER5> They moved it. It's under List Rendering now in the guide. I have no idea why. [https://vuejs.org/v2/guide/list.html#Object-Change- Detection...](https://vuejs.org/v2/guide/list.html#Object-Change-Detection- Caveats)

</comment></comment></comment></comment><comment><USER6> Vue is relatively simple and the Vue docs themselves are comprehensive and excellent.

There is a culture of complexity and some people thrive and perpetuate this complexity for not always technical reasons.

Vue completely avoids and sidesteps this and its best to start with the original site and docs or you might find yourself sucked once more into this gratuitous complexity.

</comment><comment><USER7> I've been using Vue for about a year now. It's been my lib of choice for rapid front end development. Quasar Framework with it is especially a productive combination.

In comparison to react, it's always been more intuitive.

That said, I recently started working with a developer new to vue coming from react. Explaining how nested data updates doesn't really work made me realize how janky it is.

I hope there's some kind of solution. Especially when you start using vuex, the data update inconsistency becomes a major issue.

<comment><USER8> Nested updates are always a problem, not just with Vue. Just avoid messing with attributes below the first level of nesting.

</comment></comment><comment><USER9> Can someone explain the appeal of Vue over React?

<comment><USER10> Vue doesn't force components or build tools on you. You can drop it as a 30ko script in an html tag and put the template in the html file for small projects, then go full webpack + components as it grows.

Managing state is very natural on small projects, but you can use the official, well integrated store.

The doc is stellar. The api is simple, with no surprises, and riddle with small helpers to make your life easier. As a result, reading the official tutorial feels like a friend is talking to you.

Debugging and training are easy.

I do mostly react for my clients, but when i can choose, i always go for vue.

<comment><USER4> As someone who uses Vue every day at work I would not say that Vue has a simple API, though it has many conveniences.

I think a fair comparison would be to look at React's component API: [https://facebook.github.io/react/docs/react- component.html](https://facebook.github.io/react/docs/react-component.html)

And compare it with the Options / Lifecycle Hooks and Instance Properties and Instance Methods sections of the Vue API docs: [https://vuejs.org/v2/api/](https://vuejs.org/v2/api/)

Vue may be simpler if you have passing familiarity with Angular 1, or if you are very familiar with Mustache-style templates. But I think it's wrong to say the API is simple, or has a small surface.

<comment><USER10> The naming all life cycle methods, the grouping of things by categories in data, methods, all the things you don't need to learn to make jsx do what you want, the whole props/callback things that is vastly simpler, no set state shenanigan, no two ways with consequences of creating components, the use of standard html attribute names and not js dom api names, etc.

That makes manipulating the api way simpler for me.

</comment></comment></comment></comment><comment><USER11> They could mention Weex

[https://weex.incubator.apache.org](https://weex.incubator.apache.org)

<comment><USER12> You should submit a pull request! :)

</comment></comment><comment><USER13> Is there an equivalent of this for React and Angular?

<comment><USER14> There's an "awesome-react" list [0]. Also, I personally maintain a large list of links to tutorials, articles, and resources for React and Redux [1], as well as a list of Redux-related addons [2].

[0] [https://github.com/enaqx/awesome-react](https://github.com/enaqx/awesome- react)

[1] [https://github.com/markerikson/react-redux- links](https://github.com/markerikson/react-redux-links)

[2] [https://github.com/markerikson/redux-ecosystem- links](https://github.com/markerikson/redux-ecosystem-links)</comment></comment>


A unifying approach for controlling flying robotic insects - <AUTHOR> https://techxplore.com/news/2019-11-approach-robotic-insects.html <comment><USER2> >[...] for insect-scale micro air vehicles (FWMAVs)

uh, "Insect-Scale" == 'FW'? WTF.</comment>


Inverting Binary Trees Considered Harmful - <AUTHOR> http://www.jasq.org/just-another-scala-quant/inverting-binary-trees-considered-harmful <comment><USER5> Yeah I remember the Google interview a few years back. I did it mostly for fun, and because their recruiters kept contacting me.

So there we were, building a tree out of a forest of existing smaller trees or such. That was after they couldn't find my resume, and used a 5 year old one they found some place. They seemed annoyed and tired. By that time I felt nothing short of me proving P!=NP would have help changed their mood. I mean, they didn't even ask me what I knew, what I worked on lately. Heck, I could have been herding goats for the previous 5 years, but if I could have solved that tree problem, well, Googleplex here I come, I could have been herding goats there, maybe as part of some a green eco-initiative project...

I guess half way through I just kind of decided that Google must be a pretty bad place to work at and kind of gave up. I was tempted to ask them how often they had to build the tree out of subtrees at Google. Or in this case how many times did they really have to invert the binary tree, but I am nicer that than, maybe they really did have a pretty shitty day.

Ever since then I've declined to interview at Google. I get contacted every year like clockwork "Wanna try again?", "No thanks, good luck inverting binary trees though..."

<comment><USER6> I was told by someone many years ago to always take a copy of my resume with me to an interview. That advice has paid off a couple of times. These days I also keep an email draft ready to send.

<comment><USER7> While that's good advice, I don't follow it.

If a company doesn't have their shit together enough to coordinate an interview schedule and get the right people into the right room at the right time with my resume in their hands, ideally in their hands ahead of time, I don't want to work there. It's a basic competence test.

<comment><USER8> "It's a basic competence test."

They feel the same way about you having your own resume in an interview.

<comment><USER9> I feel its more of a talisman. Who reads those things? Not at an interview; the time for resumes is over, you passed that sieve already.

</comment></comment></comment></comment></comment><comment><USER10> The last interview I did was for a node.js position. I was told to bring my laptop. When I got there, the put me in an office and handed me a packet with instructions on checking out a nearly empty git repo. Then they said "Write an API that meets as many of the following requirements as possible and push the code. We'll be back in 3 hours."

After 3 hours, I was taken to a conference room where I demonstrated the API. I also talked about a bug I had that had hung me up, but I fixed it right there in the conference room.

Got the offer. It was a great experience. I enjoyed the challenge, but it felt useful and related to the work rather than just esoteric problem that would not likely ever be required by the job, and if it was I'd have time to research it and figure it out.

<comment><USER11> That actually sounds like a decent way to do things. The only thing I'd change is making it shorter and trying to incorporate some pair programming at least to some minor degree to see how well they communicate along with developing.

<comment><USER12> Pair programming is incredibly divisive.

In a company that does pair programming, sure, do that, because those of us that hate pair programming would then instantly tell them we're not interested and leave rather than waste time on an interview somewhere we won't want to work.

But likewise, if you're not actually doing pair programming day to day, don't do it in an interview setting.

<comment><USER11> Erm, okay, I used the wrong terminology. I simply meant two people working on the same project. I didn't mean on the same workstation, that would be terrible.

</comment></comment></comment></comment><comment><USER13> I recently interviewed for (and got) a new job.

The interview process took about two weeks and on the whole was pretty reasonable for both sides.

There was a short phone screen (~30 minutes)

Then I had two technical exercises to do. For each, I was given a reasonable time period (4 hours) that started when I visited a special link to the get the problem description, and then used whatever tools I wanted to get it done, then email in the completed exercise.

The two exercises were not completely trivial, but were relatively straightforward and actually involved skills relevant to the position and not arcane puzzles or comp-sci theory. (Basically, the first was to write a Postgres schema from scratch (total 5 or 6 tables and maybe 30 columns across all the tables). The second task was to write a CSV parser (including reasonable error checking/recovery) to load data into the schema from the first problem.

Finally, there was the main interview (conducted via Facetime, this is a remote position). That ran for close to 3 hours.

This worked well, since it gave me a feel for what the work would actually be like, and I was given, as the candidate, every oppurtunity to put my best foot forward - no whiteboard exercises, no surprises.

<comment><USER14> The correct way to write a CSV parser is to import one.

<comment><USER15> Scenario: The file is a 100GB CSV file. The machine is a VPS with 500MB RAM. The task: Determine whether the value in the first column of the first row, is ever repeated in the first column of any subsequent row.

An import solution is unlikely to work. Most import solutions would try to load the rows into memory, which doesn't work here. Maybe if the imported parser can be configured to run a user-supplied callback on individual rows and then discard them...

(P.S. solving the problem with awk still counts as writing a CSV parser --- in awk)

<comment><USER16> The trivial Java solution

        BufferedReader r = new BufferedReader(new File(filename))
        String line = r.readLine();
        if (line != null) {
            String first = line.split(",")[0];
            while ((line = r.readLine()) != null) {
                if (first.equals(line.split(",")[0])) {
                    return true;
                }
            }
            return false;
        }
        throw new RuntimeException();

would work just fine, and very quickly, too. This sort of question simply is not hard to solve; it's far more dependent on tiny implementation details. I very much doubt that any CSV parser would try to load the file all at once; it'd be too much of a performance hit.

<comment><USER15> In other words, you write your own CSV parser, in this case using Java.

Btw, CSV files can contain values with commas and even newlines inside of them. So if your point was that you don't have to write an _entire_ CSV parser, only a partial one, unfortunately that isn't true. [https://en.wikipedia.org/wiki/Comma- separated_values#Example](https://en.wikipedia.org/wiki/Comma- separated_values#Example)

>I very much doubt that any CSV parser would try to load the file all at once

I agree, but a naive imported solution would likely try to store all the rows at once, possibly in some sort of list or vector or array or whatever. This is what would cause the memory failure, not the file read itself.

<comment><USER16> Possibly, but unlikely (most csv libraries will be based around iterators). In any case, the problem is stupidly underspecified. For example, what if the 100GB CSV is 100 1GB rows? What if the input is UTF16, UTF32? How do you deal with the 10 Unicode line separators?

It just tests how well the interviewee knows CSV, which is an ill specified format anyway. It's a fake problem as no sane person would parse 100GB CSVs on 500MB VPS', and in real life, you'd just try the naive solution, see why it didn't work and iterate.

</comment></comment></comment></comment></comment></comment><comment><USER17> I'll be the contrarian and claim that inverting a binary tree is a perfectly reasonable interview question. (Although not anymore now that it's famous). It combines basic background knowledge (what is a binary tree and how is it structured?), ability to reason logically (binary tree algorithms are often recursive, "inverting" a tree with no children is a no-op, otherwise you want to swap the children, and the children's children, and...), and enough familiarity in one language to write simple constructs without an IDE or stackoverflow holding your hand. None of this requires you to be Jeff Dean.

I will agree that the guy who kicked all this off has a legitimate complaint if the recruiter failed to adequately explain the interview process, and I'm sure there are lots of bad interviewers that focus on meaningless details or obscure trivia. But I don't agree that the concept of having candidates write code is fundamentally awful.

<comment><USER18> In your daily programming activities, how many times do you have to implement a binary tree? I'm genuinely interested.

<comment><USER19> I find myself implementing trees fairly often (and manipulating them even more often), but since I'm not using a language that requires lots of pointer juggling and lifetime reasoning, I consider implementing them a pretty basic task.

<comment><USER18> Interesting. What type of software do you work on? I ask because I write code for robotic control loops and looking to explore any possible angle. Someone who writes trees often could help broaden my horizons.

</comment></comment></comment></comment><comment><USER20> I'm more than happy to participate in a technical interview and I always prepare the best I can. However, I find it odd that technical interviews don't work both ways. The interviewer can ask you to solve problem x, but if you ask the interviewer to solve problem y (fair play, right?) I suspect you would be shown the door.

Interviewer: "Can you show me on the whiteboard how you would invert a binary tree?" You: "Of course." _Writes on whiteboard._ Interviewer: "Excellent!" You: "Your turn. Can you show me on the whiteboard how you would implement a priority queue first with O(1) insert and O(n) remove complexity, and then with O(n log n) insert and remove complexity."

I think even better would be to solve a problem on the whiteboard __WITH __the interviewer: one which the interviewer did not know or prepare an answer to.

\- First, it would reflect the type of problems you may have to solve in the role you're interviewing for.

\- Second, it demonstrates your interpersonal skills, your ability to de- construct, understand and then solve the problem at hand.

\- Third, it demonstrates how you work with others to solve a technical problem.

\- Finally, it puts both the interviewer and interviewee on the same level. It's not so much of "you v.s. me", but a "we". Hopefully, by the end the interviewer thinks: "Hey, I'd really like to work with this person. They're _really_ smart, solved the problem faster than I could, they were very easy to work with, etc."

I think this would make technical interviews more fair, more fun, and at last, representative of real work you would do in the role as I doubt the interviewer will want to solve the 8 queens problem under pressure either.

<comment> rkuykendall-com > I think even better would be to solve a problem on the whiteboard WITH the > interviewer: one which the interviewer did not know or prepare an answer to.

wow, that's a great idea. I would love that interview. In addition, they should solve a problem with an engineer that would be their junior and their senior, to show how they contribute to those situations.

</comment></comment><comment><USER21> The rules are pretty clear on what the interview will cover. The recruiter tells you months before the interview and they (Google) even send you a list of what books and papers to read before you consider yourself ready. That is more than fair. I just joined a start up. It consists of 3 non-minorities and 3 minorities. All three non-minorities were recruited early on because they all knew someone within the company (and they all were competent). All three minorities came in through a recruiter - expensive and the bar definitely was a little higher than the internal referral-hire process.

So In summary, I like Google's process for its fairness. They also seem to hire quite a few good engineers and a few great ones too.

<comment><USER22> > The recruiter tells you months before the interview and they (Google) even > send you a list of what books and papers to read before you consider > yourself ready.

Right, because I have nothing better do in those months than to rehash CS 101 and waste my time inverting trees and reversing strings.

<comment><USER21> Nobody is telling you to spend all your free time on CS101 for months. It shouldn't take months. Go back, pick up an OS textbook and read a few pages without all that academic pressure. I bet you'll appreciate the writing a little more.

<comment><USER23> You totally missed the point, may be this makes sense for a few people. But a whole majority of people don't find it a very good use of their time to gain knowledge just for its own sake.

If I were writing a OS, I would bury myself in all the OS books in the world, and work atrocious hours to build one. But if you are asking me to do it, because I have to face an hour of interview 6 months from now, I find this a pointless exercise.

</comment></comment></comment></comment><comment><USER24> I'm only a rising junior in CS on my second internship and I completely agree. I did really well in my Data Structs & Algorithms class (A+...) and I just hate these types of problems. I bombed Google and Dropbox's interviews, and am ready to never go through another process like that again if I can.

I've been exceedingly lucky landing gigs at great companies that don't filter with these questions. I worked for LeadGenius (YC S11!) and the technical portion of the interview was super fun and effective; I was asked to write a useful piece of software in python which I later applied to school projects! No whiteboarding, no data structures. I'm currently interning at General Motors and their interview was similarly sans whiteboarding, and I'm surrounded by brilliant interns and coworkers. Hmm. At least for me and a few of my peers, being asked to solve the type of problems presented in the article raises some red flags about a company's culture.

<comment><USER25> It's not just CS, but probably more common with CS. There are two kinds of engineers.

1\. Those that love love love solving Puzzles. 2\. Those that question whether solving this or that puzzle is going to bring in any money for the company.

For a places like google or deranged YC startups, whether what you are assigned has any bearing on cash flow is something way above the typical engineers paygrade. There are a lot of companies where that isn't true.

<comment><USER25> BTW: Bit of advice for anyone going into a technical fields.

Learn to write, English _. Learn it well. How to clearly explain idea 's and requirements. How things work, how they are broken. Justify what you did, or cover your butt. Where you are in twenty years will depend mostly on this.

Learn to speak fluently in front of a group of people.

_ Or whatever the locally appropriate language is.

</comment></comment></comment><comment><USER26> Fact is, it just isn't true. As a Googler, I am surrounded by enormously talented engineers, the likes of which I rarely encountered on the outside. They love what they do, and it shows.

I have no doubt that there are false negatives/positives, but I am convinced that Google is doing something right.

<comment><USER27> I think we do very well at hiring the sort of people who already work at Google. The false positive rate seems to be very low, and the people I work with mostly seem very happy (I know I certainly am).

The false negative rate worries me, though, and I keep wondering if there's a way I could structure my interviews (and feedback) differently to help change that problem.

<comment><USER12> You should worry about more than the false negative rate. You should worry about the reputation Google has developed that means a lot of those who have choices opt to not even consider interviewing at Google any more because it's not worth the aggravation.

<comment><USER27> I do worry about that as well, but that's a much more difficult problem as people's opinions can be damaged by so many things along the way. What works for some people[0] is a disaster for other people. The 'disaster' nature of it can come down to not liking to be on the phone, needing answers more quickly than Google can provide them[1], or just ending up with a bad interviewer on their loop[2].

Those are much bigger issues, and there are people here trying to tackle them! I feel _my_ effort can be best dedicated to making sure I conduct the best interviews possible. I start from by assuming my goal is to get the candidate to demonstrate the competencies we're looking for in whatever way possible. Yes, there's usually some coding. If the coding turns out to be a bit rough but the candidate can do a fantastic job of walking me through a previous project, it's design, what went well, what they would change about it now, that speaks very well of them. I can't claim they demonstrated fantastic coding, but I can claim that I think we should hire them anyway and justify that recommendation.

It's hard. I would like our process to be lighter weight (or at least, better weighted to individual candidates), but I recognize the importance of maintaining a small false positive rate. I work with really rock solid engineers, and that's one of the best things about my job. I can trust everyone around me to at least make good decisions (even if they're sometimes wrong, or they're sometimes not the decision I would have made, I can usually understand how a smart capable engineer would have made it).

[0]: My process was roughly as follows: phone screen (all technical, coding in a Google doc), on site ~3 days later (five interviews coding on a Chromebook, lunch; the usual mix of interview questions you've come to expect), offer ~5 days after that, mutual acceptance after negotiation ~3 days after that. So we're talking about two weeks end-to-end. Also, I actually really enjoy interviewing. I come out of a day of solving interview questions feeling invigorated. Like I said, we do a really good job of hiring the sort of people who already work here.

[1]: Some of the things that I think are very good about Google's process (particularly in terms of providing fairness across candidates in a way that my previous employer did not) also cause delays. A lot of effort goes into considering all of the data that's available on a candidate. The amount of discussion that goes into every candidate, even after all of the feedback is in, is staggering.

[2]: Remember that interviewers are people. We've all been told that we're representing Google, but some people take that responsibility more seriously than others. Given that interviews are typically conducted 1:1, nobody knows what happened in the room except for the interviewer and the candidate. When candidates have bad experiences, they don't necessarily report it to their recruiter, so if it's a systematic problem with a particular interviewer, unless it shows up in the feedback they're submitting, it's very difficult to detect and correct. This is really unfortunate, but of course putting two people in the room makes some candidates nervous as they feel they're being doubly judged!

</comment></comment></comment></comment><comment><USER28> This passage gives me a good idea:

      The OPower guy said they had a ton of problems where they
      will be using Scalding, so I asked him what they are
      doing in its absence. He said Oh we pojo it. Then he said
      pojo this and pojo that, and soon I was drowning in
      pojos, so I asked, Sorry, what exactly is a pojo ? Now,
      bear in mind I am a Scala programmer and haven't touched
      Java in ages, and they knew that. Their whole pitch was
      they wanted to inject some new Scala blood into their
      tired Java veins, and that's why I interviewed there. So
      the guy is agape, and says, you don't know what a pojo is?
      When was the last time you wrote Java?

When interviewing a candidate, use some wacky made-up term like "pojo" a lot in offhand conversation, and reject anyone who _doesn 't_ ask what it is.

<comment><USER7> pojo is a common term for java devs, at least any who have been molested by spring

<comment><USER29> It's also seen some use in the Javascript community as well (though not nearly as common).

<comment><USER30> And Ruby too (PORO naturally). Leave it to Martin Foweler et al. coin a useful [category of] term[s].

</comment></comment></comment></comment><comment><USER31> [speaking for myself only, not my employers past or present] [I am guessing this will be an unpopular opinion, so posting anonymously]

I feel that interviews are essential. Every alternative I've heard seems to not work. I've tried.

0\. Review their contributions to open source

\--a. Some brilliant people have none - they prefer to get paid for their work & not disseminate it openly for free - that does not mean they should be disqualified

\--b. I've personally seen people with stellar resumes claiming to have contributed to many projects who could not even tell me when they'd use a hashtable in any scenario of their choice

1\. Ask about their last project

\--a. It is easy to lie, to any level of detail. Anyone who tells you otherwise has never watched a politician speak.

\--b. Speaking about engineering (even well) does not mean you can actually engineer well.

2\. Pair program with them

\--a. This tends to waste a lot of time, since either you use an abstract problem (and you're back to a normal interview) or you use a real problem and you spend 10000 hours explaining it.

3\. Hire them on a trial period

\--a. This is insulting to the brilliant people

\--b. This is a waste of company time on the not brilliant people

<comment><USER32> Trial period: It's not just "insulting" \- I wouldn't do it. If I have a job I'm very satisfied with and you dragged me to your place in order to interview after contacting me. I won't be willing to spend a week in a trial.

This is a sellers market anyway.

What we found works is asking _practical_ questions and not theoretical ones. You can ask people to code with a computer and internet and whatever editor they want simulating a real environment.

</comment></comment><comment><USER33> IMHO, I feel like people who are not up to it don't agree with coding interviews. Also, in my experience, the employers that didn't check coding skills at the interview had the worst engineers I met (surprise!).

Now I can see why it's easy to disagree with interviews that check your algorithms 101 knowledge: that stuff is really really rarely used in real-life and you can just google it if you ever need it. But! Keep these in mind:

\- Can you come up with a better process that scales with the number of interviewers in your company, but also maintains reasonable consistency and keeps reasonable costs? Maybe you think you can, but keep in mind that the tech giants have data-crunched their interview stats over and over and this process is what they stuck with. (Of course, with scale there's also the problem you occasionally have arrogant interviewers - but I think that problem should be decoupled from the coding/non-coding interviews problem).

\- In places where they look for A* engineers, the point of the interview is often not to test what you know best, but how you get along with problems you have never seen before. An algorithm or data structure question often fits the bill.

\- Geeks love geeky puzzles (like inverting binary trees). Companies often look for geeks in love with abstract stuff.

Also, IMHO, knowing only one language is a red flag for me too at 10+ years experience level.

<comment><USER9> I think its just inbreeding. Folks who know that stuff, hire folks who know that stuff. Like any other industry we are self-selected for similar types. Never mind the discrimination issues; we're a very narrow-minded population. Better engineers could be found with other sieves.

</comment></comment><comment><USER34> I love interviewing and being interviewed. Don't know why but I do. However, I hate these types of interviews. I mean, sure if I am a new grad or you suspect I might not know my shit, ask me some probing questions. However, almost nobody these days needs to invert a binary tree or compute the hash of a string by hand.

Here is my secret go to question when interviewing someone: "can you describe how an AJAX request works, from start to finish?". The answer involves knowing that AJAX works over HTTP, same as regular page requests, knowing what IP, TCP, and HTTP are, and how client and server interact using them. It is a question most competent people can answer, yet it has lots of room for depth of detail. By discussing technical subjects, challenges and solutions I think you get a much better idea of how good someone is vs some predefined set of puzzles.

</comment><comment><USER35> I enjoy the challenge of programming interviews. When I interviewed in Mountain View, I thought it was just super cool to have been invited. It was like the mother ship had summoned me home!

I was mega-underwhelmed when I botched the last session, though. And after doing so poorly, no one escorted me out or summed things up. Efficient, I suppose -- I'd met with the recruiter at the beginning of the day and there was nothing left to discuss. But there was no denouement. A big build up all day and all of a sudden -- nothing.

That last session I was asked to implement a particular matrix manipulation. IMO a bit more utility than tree inversion. And I tried to talk through my thought process but I'll admit it just wasn't getting there. After it was over, I went back to the hotel, wrote a test case and kept coding until I made it work. I'm a little ashamed to admit that it took 1.5-2hrs to get it to work -- so probably not just intimidation/stage fright. After writing the code, I don't think I understood the design well enough to explain it -- but I did do it on my own w/o any reference. I guess I wasn't surprised when I didn't get an offer.

So I've been contacted again as a part of this latest hiring campaign. I'll give it another try, I suppose. My ego's buoyed by being contacted again and doing well on phone screens, so I suppose I can take another bruising. :)

<comment><USER36> To fill in one gap - our hiring process has an extra layer of insulation to better control individual biases. Your interviewers all submit feedback and an independent hiring committee makes the decision, on a different day, with all due deliberation.

The reason nobody has anything to say to you at the end of the day is because none of that has happened so nobody knows what to say at that point, and I don't think it's likely to make you feel better to have somebody give you a completely generic speech that has got nothing to do with you.

As for the more general thing that keeps popping up - do people seriously believe that all the thousands of Google engineers who do interviews haven't figured out that people writing code on a whiteboard under stress aren't the same thing as people sat at their desk grinding out code?

<comment><USER37> Yes, "thousands of Google engineers who do interviews haven't figured out that people writing code on a whiteboard under stress aren't the same thing as people sat at their desk grinding out code?" I am pretty confident they don't know that. I know people way smarter than me who flunked the google interviews and, working in the same building, know even more that got in who are very good but not great. Also, they are ageist and "don't consider experience at all" (and that is from a direct quote from a person in an interview).

<comment><USER36> Here's an alternative hypothesis: the interview process is selecting for different traits than what you are expecting.

[https://www.google.com/about/careers/lifeatgoogle/hiringproc...](https://www.google.com/about/careers/lifeatgoogle/hiringprocess/) is a pretty good explanation.

<comment><USER37> The whole point of this topic is they don't consider role related experience.

</comment></comment></comment></comment></comment><comment><USER38> >You are then ushered into a room with the programmer's worst nightmare - <USER3> blank whiteboard.

Am I the only one who enjoys programming interviews? Even if you screw it up, it's still fun to try your hand at whatever problem they give you. They also don't expect you to do it perfectly; you're allowed to have sub-superhuman performance.

<comment><USER39> I interviewed at Microsoft and it was about 10 hours of this stuff and I loved it. Had a great time, and I think I did pretty well. One guy wanted me to write a shuffling program. So I came up with one which I later discovered was Fisher-Yates and optimal. But he kept saying "how can it be faster" so I'm not sure what I was missing. Most of the other stuff was pretty fun and straightforward - pointer stuff, string copying, synchronization. It felt like if you had gone through Sedgewick's algorithm book you'd be set for the most part.

Unfortunately by 7pm or so I was sorta exhausted (didn't sleep the night before 'cause I was so excited). I met the hiring manager, and he asked something fun like make a ring buffer and also write a non-recursive inorder traversal function of a binary tree. I apparently had some off-by-one bug in the ring buffer code, and then I just blanked out on the traversal question. No hire :\\.

(OTOH, that team wasn't sure if they were going to be using VB6, or C++, or maybe .NET, but probably not because they wanted to ship with Office and Office severely limits dependencies. So maybe it was for the better.)

<comment><USER40> Sounds like a blast.

</comment></comment></comment><comment><USER41> Funny, I thought this was going to be "inverting binary trees considered harmful" because the sensible way to do it is to change your traversal algorithm to be right-before-left, and leave the data alone. Silly me!

</comment><comment><USER42> Not sure what OP is being proud of exactly. I was subjected to this style when I interviewed at Twitter.

Sorry my op sounded like I was accusing the author of something but this whiteboard approach is what I did at Twitter.

<comment><USER11> Yeah I don't think OP was defending Twitter I think it was just more of a story about how crappy the interview process is at most tech companies.

My experience with Twitter was really odd. I knew someone internal and had them directly submit my resume with a recommendation. The resume was tailored for exactly the position they wanted showing me besting all of their requirements. I got an email 4 months later telling me my resume was not good enough for even a phone screening. I've never had that happen before and it's still perplexing.

<comment><USER43> It's possible the position was filled, so some hiring manager just cleared the queue.

<comment><USER11> Good point; never really thought about that. I just found it odd because their email response actually gave me a reason stating my resume didn't have enough experience for the position when it far exceeded everything they wanted for the position.

<comment><USER43> At least in our resume-tracking software, there's a bunch of pre-canned messages you can use if you choose to, I imagine it's much the same there.

</comment></comment></comment></comment></comment><comment><USER44> That was very funny. The failed Ruby interview with the soon to be defunct HN company was hilarious.

It's a good advice to go out to interviews from time to time. Just to see what's out there.

</comment><comment><USER45> There's not so much a shortage of talented programmers as there is a shortage of people able to identify talented programmers.

If there's anything in need of serious disruption, it's the adversarial hiring process in technology. It's all mindless cargo-culting, and it doesn't actually work.

<comment><USER46> > It's all mindless cargo-culting, and it doesn't actually work

amen.

</comment></comment><comment><USER47> I don't think inverting binary trees is the problem per se. I mean, algorithms are the bread and butter of programming. You should be able to implement simple ones like that even if you'd never actually do that in practice. The real problem in my opinion is the whiteboard and time pressure.

<comment><USER48> I gave this example on Reddit this morning, but I'll repeat it. If a programmer was given an array of elements [a1, a2, a3, a4, ..., an-1, an] and asked to produce the array [a2, a1, a4, a3, ..., an, an-1] and couldn't do it, he'd be the laughing stock of /r/programming for a couple of days and we'd hear about this problem for years to come, the same way we hear about FizzBuzz. Certainly a programmer should know how to traverse an array and manipulate its elements!

For the case of inverting a binary tree, we haven't gotten a clear answer to what it means, but the concensus seems to be to swap every left and right nodes in the tree. Well, that's exactly like the array problem above: traverse the structure and manipulate its elements! The traversal is not a simple loop, you use recursion (or if you're fancier, use an explicit stack to avoid causing an overflow of the call stack), but I'd argue that recursion is a fundamental notion for a programmer to know.

A commenter on Reddit mentioned that there's a difference between programmers and computer scientists and that the programmer is responsible for writing software and the computer scientists are responsible for coming up with algorithms and data structures. But then, what do the programmers use? If we cannot expect them to know about trees, what about linked lists? Resizable arrays? Hash tables? Graphs? These data structures are extremely important tools for creating solutions, shouldn't programmers be aware of them and how to use them?

<comment><USER49> A couple of things:

1\. I think phrasing matters a lot. Saying "invert a binary tree" creates an immediate suspicion in my mind that what I'm really being asked is not "do you know how to swap elements", but rather some kind of weeding-out trivia looking for a specific, probably named-after-a-person, algorithm they're expecting me to remember from a college course (tricky for me in particular, as I didn't do CS in college).

2\. A whole lot depends on the context of the interview. While I know what a binary tree is and how it works, I've _never_ \-- in 11 years of programming professionally, and several more as a recreational/amateur before that -- actually needed to implement or even explicitly use one. There are a lot of things people will deride lack of knowledge of, things that people will consider to be hugely important CS fundamentals, that can literally just never come up in a lot of programmers' careers because they are not actually universally fundamental in all fields of programming.

So jumping into things that aren't relevant to the field you're interviewing for can achieve the opposite of what the interviewer hopes for: it's putting the candidate off-balance, but in the wrong way by making them wonder if they're interviewing for the wrong job or misunderstood what the job actually involved. Which in turn is going to affect their performance.

</comment></comment></comment><comment><USER50> A lot of these posts don't actually address the problem of hiring and filtering people. If you think whiteboard tests or logic puzzles are not effective, why do you think this and what is a better alternative?

I personally think they are ok, but should more be a means to test if the candidate can reason intelligently and it shouldn't matter much if the end answer they get is correct or not.

<comment><USER51> Work sample tests, of course. Basically everybody who read the literature knows what is the better alternative.

<comment><USER52> Coding a simple algorithm is a work-d sample test.

</comment></comment></comment><comment><USER53> Twitter interview went sideways, I got one shot with a question (that I won't share) that required finding Hamiltonian path in a tree, over the phone of course. I am not sure what is the mindset of the interviewer.

I am hiring engineers (systems, software and security) in the last 5 years, got trained up on recruiting by Amazon, so I would say I have a pretty good understanding on hiring.

The right approach with these interviews to find out the best of the candidate. In order to achieve that you always start with simple questions like what is a variable, what sort of data is out there, do you use version control etc. After that you switch gears.

On the subject of inverting binary trees on a whiteboard. Is this the core of your business? How many times did you need to do that last week? If it is irrelevant for your daily operations than why are you asking this question?

The problem is that (especially companies like Google) like to hire Stanford graduates and those guys think after being in the job for few months that the best way on interviewing is to measure how well the candidate would have done during the last semester in theoretical CS class at the university. While we probably all know that running a service for millions of users in production in a distributed environment requires many other skills that are not represented too much in the interviews, yet this is what you can run into during the interview loops.

I think at certain extent this is known to the Google recruiting team and they are ok with it. The way to beat the interview is to read books like Cracking the Coding Interview and train up extremely well on those trees and search algos and all, if you are really committed to work there. There are several very senior guys turned down by Google simple because they failed one or two of these ridiculous questions.

I think the last incident kind of a good example of this:

[https://twitter.com/mxcl/status/608682016205344768](https://twitter.com/mxcl/status/608682016205344768)

Now I get back to my read about how the heck I am inverting a binary tree.

<comment><USER52> Loops in a tree?

<comment><USER53> Thanks for pointing out, my bad, fixed now. I meant Hamiltonian path. Guys might have leaked on Glassdoor among other questions.

</comment></comment></comment><comment><USER54> Context for the title: [https://twitter.com/mxcl/status/608682016205344768](https://twitter.com/mxcl/status/608682016205344768)

</comment><comment><USER55> What does it mean to invert a binary tree?

<comment><USER56> To change the nodes to point the other way around. So if the left edge of N1 points to N2 and the right edge points to N3 you make it so that N1's left edge points to N3 and the right edge points to N2. It's a trivial problem of changing pointers around. It's like 4 or 5 lines of code if you write a recursive function.

<comment><USER57>
        def invert(node):
            if node is None: return
            invert(node.left)
            invert(node.right)
            node.left, node.right = node.right, node.left

Yep, pretty much. But, to be honest, if you hadn't described it I wouldn't have had a clue what was meant by inverting a tree. Zippering it or something? I wouldn't know.

<comment><USER56> You can ask the interviewer to clarify what the question is or what the result should look like. You should always ask for more details ask if you don't understand the question, and sometimes people ask in a vague way to see if the candidate will ask for clarification for better or for worse. It will not make you look stupid.

The simple action of saying "I don't know what you mean by X" or "I don't understand what X is" builds up your credibility, not reduce it. People who aren't afraid to ask questions demonstrate credibility because when they do say they know something you know they probably actually do.

I have learned so much from not being afraid to say "What is X" when someone starts talking to me about something and assume I know what it is already.

Nobody has ever laughed at me for this. Even if they did, it wouldn't bother me, because I'd rather I look silly and then learn what it is than to pretend I know and then actually end up not learning what it was someone was talking to me about.

Finally if they did think you should have known what the topic was you'd rather they know that about you while they're evaluating you not after you're hired and end up in over your head. This is a really unlikely scenario. These interviews are not so much about what you know, but how you solve problems.

</comment></comment></comment></comment><comment><USER58> I interviewed at Google twice in Mountain View after getting through the whole phone interview and coding process each time, but failed in person. I was way too nervous and performed poorly, but did well enough that they wanted me to come back a _third_ time. I said no thanks.

Ironically, I wound up working at Google anyway after my startup (where I was a core developer for years) was acquired. Another case of real-world skills not being borne out in Google's interview process.

</comment><comment><USER59> Is there a reason the standard response isn't "I write code for money. Are you giving me money yet?"

"Don't give it away for free" is the rallying cry of photographers and graphic designers. Why is it not for programmers?

</comment><comment><USER60> It's stuff like this that makes me glad I'll never be an employee again. I work for myself, and it may not be as "prestigious" as Google, Facebook, etc, but at least I own my time, and I don't have to deal with self-important jackasses (except myself!) telling me I have to be to work by 11am to make 150k (a pittance, really) in Silicon Valley.

</comment><comment><USER61> Data counter-point: When I interviewed at Google, I used "echo foo" in my Java code through two white-board coding interviews, and I still got the job.

Sure, there are some terrible interviewers in the Valley (and I've been interviewed by some) but there are also some terrible interviewees (candidates?) out there.

</comment><comment><USER62> I know Google interviews generate a lot of traffic on HN but I thought that I'd add something that I haven't seen covered, that is, the job itself.

I interviewed twice successfully for Google and the interview experience was impeccable (interviewers were great, HR was completely on the ball etc.). The first time there was a hiring freeze so that didn't go anywhere, the second led to offers in several countries in Googles empire. Most of these I could not accept for family reasons but one I could although Google were quite secretive about what the job was.

I accepted thinking that, well they know me well enough by now and what I can do. A mistake. Upon arrival it turned out to be writing an Android app which is completely the wrong end of the spectrum for me - I have never even written Java. I was been benchmarked against people who seem only to have done only that. The other thing that made me realise that I had no long term future in Google is that it was made clear to me that any experience of working for other software companies or other industries was neither interesting or useful. If you have a lot on your C.V. like I have this is problematic.

So I left after a few months.

Sure Google is a fabulous company, does some amazing stuff and has some great people (perhaps not as uniformly great as they'd like you to believe). If you fit the mould tightly enough you will have a lovely time.

TL;DR - They should not have hired someone like me, I should not have accepted.

</comment><comment><USER63> > You are then ushered into a room with the programmer's worst nightmare - <USER3> > blank whiteboard.

It may be the case for a few, but some people (including me) feel pretty comfortable with a white board. There's nothing hard in using a whiteboard. It's just a big sheet of paper...

Then if people think that they will never have to use a whiteboard to explain the design of their system to someone, maybe it's because they just "design" simple system.

</comment><comment><USER64> Sure it is bullshit. But it is also highly trainable. If you want a job, spend a month at [http://hackerrank.com/](http://hackerrank.com/) and similar sites and just get better at it.

I think most engineers will pass after that. Oh, and always use a language you are very comfortable in. Just stay safe and boring. I think all companies will let you pick the language as long as they have heard about it.

</comment><comment><USER65> He should name those HN companies, really entertaining read after yesterday's blow up. We need to start a hashtag and trend invertingBinaryTrees

</comment><comment><USER66> That was a really entertaining read. I'm not involved in the interviewing process often, but I'd like to be better prepared for the future so that I can ask meaningful questions and not waste anyone's time. I certainly won't be asking anyone to invert a binary tree.

</comment><comment><USER67> This burns a little as I got turned down for a job I think I would have done really well at. I'm wondering what I did wrong exactly. I accepted defeat as graciously as I could but I don't know what my future holds.

I love programming but I'm wondering if programming doesn't love me.

<comment><USER68> I wouldn't fret about it too much.

There are a lot of interviewer egos out there and kids being put in the position of Ultimate Power(tm) can really do a lot of damage to the self-worth of qualified candidates.

Just keep coding, studying algorithms, etc, and putting yourself out there. Eventually you'll get a job that you want and is well suited for you. You're fortunate to live in a time where it's a seller's market, employment-wise.

</comment></comment><comment><USER69> This type of interview questions worries me. My nervousness then permeates throughout the whole interview so I've never been asked these type of questions, which is unfortunate as perhaps it's not as bad as I make it.

Someone recommended Skiena's "The Algorithm Design Manual" and I picked it up. If you feel like more exposure to data structures can be useful, it has a section titled "A Catalog of Algorithmic Problems" which I find useful to read before an interview.

<comment><USER70> Coursera has a couple courses coming up:

Algorithms: Design and Analysis, Part 1: [https://www.coursera.org/course/algo](https://www.coursera.org/course/algo)

Algorithms, Part I: [https://www.coursera.org/course/algs4partI](https://www.coursera.org/course/algs4partI)

</comment></comment><comment><USER71> I faced similar experience but here in India , since good interview questions are rare , most of the times questions are repeated from forums such as Career cup , I was asked questions irrespective of my role . I do take interviews at my current organization and ask simple practical problems with very simple solutions but most of the times candidates think in terms of complex data structures instead of simply trying to solve a problem, they do premature optimization and what not .

</comment><comment><USER72> I guess encouraging their employees to interview is Twitter's strategy for retaining them by reminding them how much they don't want to be looking for a new job.

</comment><comment><USER73> > So it exponentiates 31 by one less than the length of the string and > multiples that with the first character's ascii, then exponentiates 31 by > two less than the length of the string and multiples that with the second > character's ascii, and so on and so forth, and sums the whole mess. And I'm > supposed to know this.

It's not such a "mess" if you see that it just evaluates the string as a polynomial.

<comment><USER74> And then the author writes:

> Now, in his defense, computing the dot product of the string with a random > prime vector is a well known Universal Multiplicative Hash Function, but > forgive me, father, for I did not pay much attention to this invaluable > nugget in my Algorithms 101.

Well, I didn't pay much attention in such a class either, but isn't that just intuitively obvious? Dot-product a vector `x` with a vector `p` of (unique) primes, and well, you've got yourself a number unique to `x`.

<comment><USER75> The question was explain the exact approach Java uses to hash strings, not come up with a way to hash string or explain why does this particular approach work for hashing strings.

Much like hashes themselves going one direction is much harder than the other.

<comment><USER16> Meanwhile, my actual Google interviewer asked me how I might do it. He then explained why my Gödel numbering scheme was bad, showed me how Java does it, was seemingly satisfied enough and offered me a job on his team.

Google has a bad rep, but it is _possible_ to sort it out.

<comment><USER75> That sounds eminently reasonable.

</comment></comment></comment></comment></comment><comment><USER76> Interviews requiring genius-level capabilities for doing boring daily trivial stuff. Quite deceptive. There is a rush in SAT and automated tests (e.g. hackerrank) stuff that is getting crazy. Anyway, no matter how good you do in SAT/programming tests, you may be discarded because of your personality, political views, or even because of plain xenophobia. Brave new world! :-D

</comment><comment><USER77> I just interviewed at a company that asked me to invert a binary tree on a (virtual) whiteboard. In fact, they asked me twice! Once in the initial technical interview, again in the follow-up!

Haven't heard back yet but I'm really disinclined to keep talking to them.

</comment><comment><USER78> The problem that I see with the interview process is the same problem that I see in computer science cirruculum: focusing too much on things programmers should know, rather than how to know things.

</comment><comment><USER79> Really fun article. I cannot make a point about the state of affairs of recruiting in SV because I've never been there, but those examples of interview processes are quite daunting.

</comment><comment><USER80> While I'm completely, 100%, against these kinds of questions, how else can a company that receives thousands of resumes a day filter out the good from bad?

<comment><USER81> It's actually not that hard -- invite them to work with you on a small project. Pay them reasonably. See how they work in RL. Then decide, and -- by all means -- give them honest feedback even when not hiring.

<comment><USER82> We did that one time. On the one had it worked very well. The person wasn't a good fit on the team so we declined. On the other hand it was emotionally draining because the guy was a really nice guy. It's really, really hard to work with someone, get to know them a bit and then at the end say, "Sorry, you're just not for us". I think it was even harder for the candidate who didn't clue in that they weren't doing very well. They met the team, got to know people a bit, got to feel the atmosphere and started to imagine what it would be like to work with us.

In the end it was such an upsetting experience for everybody that we agreed never to do it again. I think there are probably ways to make it work, but you need to be really careful to maintain some distance... But then, will you get the result you are looking for if you do?

</comment></comment></comment><comment><USER83> Probably my favorite hiring writeup of all time. So good!

<comment><USER84> I think you are underestimating the sheer magnitude of writing that is that piece of literature.

<comment><USER83> The subject matter might elude me in its technical details, but oh how he got his point across ;)

</comment></comment></comment><comment><USER46> i saw the thing on twitter earlier. what i don't get is why not ask the question of what that means? its such a simple problem once you know... and irl you don't know everything, if your interviewer expects it then you reject them for being a bad place to work.

</comment><comment><USER85> Anyone know what a dag is? Seems like a term from finance, but it is literally unGoogleable.

<comment><USER86> Erm, it's the second result when I google 'dag'.

<comment><USER87> Your Google but not his.

</comment></comment></comment><comment><USER88> Interviewing is hard. Both for the candidate and the interviewer, if he/she knows the value of hiring - as assessing the overall qualities of a candidate in a one-hour chat is mostly impossible. Also, you're interviewing someone whose future life depends on the outcome of that exam, to some extent. That makes a fraction of the people you interview very nervous and thus perform badly. Then, you have the introverts, and people that don't have great communication skills, who usually get the interviewer in a bad mood because the conversation gets uneasy. It's really a minefield not to create a huge amount of false negatives. So, I agree that uber-specific CS questions would just test your memory, or more precisely your luck. That's the same as "cultural fit", only in terms of technology.

My strategy, when interviewing is: \- If the candidate has some FLOSS project he mentions in his resume (we actively encourage them to do so), I take a look at his/her code. That is usually one of the best indicators of their abilities. If the project is interesting, I usually start the interview from it. \- Ask general questions which a candidate for this position should reasonably know. Try to get the candidate to talk to you, and then try to get the conversation to a more detailed level, to test how deep the knowledge of the field has gone \- Ask the candidate to talk to you about something they have passion about in the tech field, a project they loved to work on. Again, use things the candidate is describing to get to dig a little deeper \- Look at the CV, find any language that the candidate affirms to know well and to use daily, and ask some specifics about it. \- Finally, make a small thought experiment of building an application.

These are normally questions that should not weed out anyone because they don't remember that particular detailed thing I love so much, and still weeds out very quickly whoever is superficial, or is pretending to know things he/se doesn't know.

You'd be amazed how many "rockstar web developers" fill their mouths with "RESTful webservices" and then have no idea of which the HTTP caching headers are. Or what's the HTTP status code for Not Modified. Or by how many python "hackers" can't tell the difference between a list and a set in their favourite language.

So, I definitely try to make the candidate be in a comfortable place during the interview. I know of at least one guy that told our internal recruiter that I use the interviews to show off... and that was because I explained a senior Java programmer that yes, Java's GC system is a bit different than Perl's.

So be advised, sometimes people are just bitter with the interviewer because they performed badly and can't admit that to themselves.

</comment><comment><USER89> Before reading the discussion let me just say that this is a trivial problem with a 10 lines solution which I expect anyone be able to write correctly on the first attempt and I would not want to hire someone who can't do it.

</comment><comment><USER90> > _The first programmer with /without a shadow walks in. He's quite annoyed, > because he was neck deep in jira or git or debugging some hairy stack-trace > on eclipse, and he's been unceremoniously yanked off to interview YOU - <USER4> > new dude, who has no fucking idea how things really work here. Well, he must > show YOU your place. You lowly worm..._

Oh man, I hope I n ever come off that way when I'm the interviewer. I always try to give myself a good fifteen to twenty minutes to cool down before the interview and get prepared mentally. But I generally kind of look angry when I'm thinking and listening. Would it be helpful to explain to candidates that I have rbf?

<comment><USER75> _I always try to give myself a good fifteen to twenty minutes to cool down before the interview and get prepared mentally._

You're lucky you get a heads up. On more than one occasion I've had a manager come up to me and say "We're in the middle of interviewing a candidate right now in conference room X. Please come and ask a few questions and see what you think of him".

</comment></comment><comment><USER91> This just comes off as a bunch of bragging with the issue in the title sitting in the periphery. Also, people would be well served to realize that companies use these tests as a proxy for intelligence and education. They very much try to avoid making it a trivia contest.</comment>


After the Lockdown, Fear and Chaos in India - <AUTHOR> https://www.nytimes.com/2020/03/25/opinion/india-coronavirus-lockdown.html <comment><USER2> Good reading</comment>


Ask HN: Why has my post disappeared? - <AUTHOR>

I have just realised my Show HN post: Show HN: Demanjo news preparing to take on Google news has just disappeared from the homepage. Can anyone provide reasons for this? Does the moderator determine which post stays on frontpages? Thanks. <comment><USER2> I see it still: [https://news.ycombinator.com/submitted?id=Dasync](https://news.ycombinator.com/submitted?id=Dasync)

It likely dropped off the front page due to:

1) Not enough upvotes

2) Lack of comments may be a factor in the scoring

3) Upvotes look suspicious, like a vote ring, so you have been penalised

For the numbers of votes (5) in the time given (an hour) on what is a working day across most of the world... it's actually surprising you _got_ onto the front page.

</comment><comment><USER3> When was it posted? What was its ID? Did it make the Front Page? Or are you asking about something else? What have you done to investigate it? Did it have a URL?

With so little information, how do you expect us to help you? Do you want us to do all the work?

Added in edit: It appears that it's an identical URL to the one you posted just under 3 weeks ago, but with a different title. Perhaps the mods detected it as an exact duplicate and killed or penalized it.

Added in further edit: [https://news.ycombinator.com/item?id=8221248](https://news.ycombinator.com/item?id=8221248)

It still exists, but I suspect it has dropped down the rankings because it's an exact duplicate and has attracted a "duplicate penalty."

<comment><AUTHOR> Thanks Colin, it was posted about an hour ago. It was on front page and also on Show HN page. Then in a twinkle of an eye, it has just disappeared. I don't have the ID and didnot keep the url.

Added in edit: It is not a duplicate post. They all have Show HN as titles. The first time I posted, there was no news section. The news section was just added this weekend. Does that make it duplicate post?

Added in further edit. I see this post has also been taken of the front page.

<comment><USER3> It is an exact duplicate - the URL is identical. It doesn't matter if the content of the page changes - HN does not fetch the page and compare contents, it compares the URL. That was the same.

And this post will have been hammered by flaggers - it's meta, and it will be perceived as complaining about flags, down-votes, or rankings. As such, it's regarded by many as "noise", detracting from the main point of "articles of interest."

</comment></comment></comment><comment><USER4> This post was killed by user flags.

The previous post dropped in rank because it set off the voting ring detector, hard. Users also flagged it.

</comment><comment><USER5> "If you need help with Hacker News, email email@example.com."

[http://www.ycombinator.com/contact/](http://www.ycombinator.com/contact/)</comment>


Victor.js – 2D Vectors for JavaScript - <AUTHOR> http://victorjs.org/ <comment><USER2> Why not use something like Numeric.js and use regular arrays? Seems like a lot of trouble to do simple vector math, and this library is specialized only to vectors. To mix vectors and matrices, you need to convert these back to arrays anyway.

</comment><comment><USER3> Just want to throw in [http://glmatrix.net](http://glmatrix.net). It supports vectors and matrices, Node and the browser and is crazy fast. (No affiliation!)

<comment><USER4> You wouldn't happen by chance to know of any libraries for doing geometric calculations? I would like a library that can handle rendering ellipses, determine if two ellipses intersect,if a line intersects or is within an ellipse, etc.

<comment><USER3> Drawing ellipses is easy. Just pick any canvas library: [https://developer.mozilla.org/de/docs/Web/HTML/Canvas#Librar...](https://developer.mozilla.org/de/docs/Web/HTML/Canvas#Libraries)

I'm afraid you have to calculate the intersections yourself though. I know there is a Processing(.org) plugin that does that kind of thing (might be called "intersection") and Processing can export to JS. I hope this helps at least a little bit.

</comment></comment></comment><comment><USER5> Nice clean library. I guess the vector object is kept mutable because of performance reasons? When actually calculating with this I see a lot of copying (and thereby allocating) going on. For a while I've been looking for a library that is immutable, but also is fast (minimal allocations).

I was thinking of the use of a JS sugaring compiler that splits the vector up into into 2 numbers (2 arguments for functions, 2 variables when declaring, etc). Alternatively some way to combine the two numbers into one and splitting them again each time the vector is used. Both give you an immutable vector implementation that also has 0 allocations.

This can make a big difference in usability and performance for game-like applications. Any ideas?

</comment><comment><USER6> I was using Point class in Adobe Flash for many years ([http://help.adobe.com/en_US/FlashPlatform/reference/actionsc...](http://help.adobe.com/en_US/FlashPlatform/reference/actionscript/3/flash/geom/Point.html) ), so I had to reimplement it into JS, it is part of my IvanK library - [http://lib.ivank.net/?p=download](http://lib.ivank.net/?p=download) . But honestly, there are like 7368 implementations of two-float object, we really need one more :)

</comment><comment><USER7> They should also do a permissions and verification system called Clarence.

<comment><USER8> and a custom confirmation dialog called Shirley

<comment><USER9> Numerical calculations library called Matt?

</comment></comment></comment><comment><USER10>
        .subtractY(vector)
        .multiplyY(scalar)

that bothers me a bit

        .rotate(angle)
        .rotateBy(angle)

that seems to be a bit... of a weird default? rotate and rotateTo would be more expected personally

</comment><comment><USER11> There is already Vector2 in Three.JS that has nearly all these functions. Why not just work on that library? The math library is separable from the code of ThreeJS anyhow.

</comment><comment><USER12> did some kid code this or why is this top news?

</comment><comment><USER13> really like the playful flying airplane.

</comment><comment><USER14> How is the demo arrow on the logo made?

<comment><USER15> There is a <canvas> overlaying the whole top section of that page onto which the arrow is being drawn.

</comment></comment><comment><USER16> very nice documentation! Sorry for the lack of depth of my comment, I don't need vectors...

<comment><USER7> How do you get anywhere?

<comment><USER3> You're funny :)</comment></comment></comment>


Facebook Will Soon Detect What You're Watching and Listening To - <AUTHOR> http://www.wired.com/2014/05/facebook-will-soon-detect-what-youre-watching-and-listening-to/

<comment><USER2> More official info at [http://newsroom.fb.com/news/2014/05/a-new-optional-way- to-sh...](http://newsroom.fb.com/news/2014/05/a-new-optional-way-to-share-and- discover-music-tv-and-movies/)</comment>


Wikileaks - good or bad for the people? - <AUTHOR>

I think it's good.  I think they stand to remind everybody that in every system checks and balances should be maintained and if the system can't do it, it's good that citizens hold to it.<p>Discuss :) <comment><USER2> Wikileaks is the part of journalism that corporate-run news rarely ventures into.

</comment><comment><USER3> I fail to see any way Wikileaks could be considered "bad for the people." It might be "bad" for secretive figures such as politicians and corporations, but I can't imagine how these leaks could have a negative effect on the general public.</comment>


Why does HN on iOS Safari not show comments? (Screenshot) - <AUTHOR> http://imgur.com/a/VF9bJ <comment><USER2> Do you have an ad-blocker installed?

<comment><USER3> That would be my guess, and less you're on iOS 11 beta and something weird is going on. I'm on iOS 10 right now on an iPhone and I see them just fine.</comment></comment>


1,700-Year-Old Board Game Found in Norwegian Burial Mound - <AUTHOR> https://www.lifeinnorway.net/archaeologists-find-roman-iron-age-board-game-in-norway/ <comment><USER2> Don't know what drove them to say it is an early form of Hnefatafl, other than that both are games played on a board. Hnefatafl games (there are several [1]) are pure strategy open information games using different pieces with different moves. This discovery is of a game played with dice and apparently identical pieces. There are no pictures of the board. so I can only speculate about it, but my guess would be this game is probably a race game, perhaps a distant relative of backgammon.

[1] [https://en.wikipedia.org/wiki/Tafl_games](https://en.wikipedia.org/wiki/Tafl_games)

<comment><USER3> It's actually not clear at all what the rules are for Tafl. Linnaeus instructions are suggestive, but certainly wrong/incomplete and people think stuff like Fetlar rules are probably close, but we really don't know.

</comment></comment><comment><USER4> We changed the URL from [https://archaeologynewsnetwork.blogspot.com/2020/05/1700-yea...](https://archaeologynewsnetwork.blogspot.com/2020/05/1700-year- old-board-game-found-in.html) to one that is almost identical but has more information. Is archaeologynewsnetwork a blogspam site? Or was this a case of both articles working off some press release?

<comment><AUTHOR> I honestly don't know. I just posted the one I encountered. But after some googling, this seems to be the original source: [https://www.uib.no/en/culturalhistory/135652/gaming-roman- ir...](https://www.uib.no/en/culturalhistory/135652/gaming-roman-iron-age)

<comment><USER5> Great link. I like the four sided stick dice.

</comment></comment></comment><comment><USER6> Expecting the Hasbro/Parker Games DMCA take down notice at any time :-)

More seriously, I think it is pretty interesting that board games would be the thing that meant this person was automatically considered aristocracy and upper class because they had board games buried with them. Today of course someone with a lot of board games or a love for them is often just considered a nerd. Perhaps nerds ruled Norway at the time. That's an interesting thought too.

<comment><USER7> I believe the ancient Egyptian aristos had their nerds buried with them.

</comment></comment><comment><USER8> The instruction booklet is ALWAYS missing when you find on old board game you want to play.

</comment><comment><USER9> It's a prototype, but don't worry, the Kickstarter backers should have theirs within the year.

</comment><comment><USER10> Thoughts of Jumanji come to mind... "Don't open the ancient Norweigian burial mound!" <g>

No, but on a serious note:

>"These are status objects that testify to contact with the Roman Empire, where they liked to enjoy themselves with board games."

and:

>"People who played games like this were local aristocracy or upper class. The game showed that you had the time, profits and ability to think strategically," said Ramstad."

Fascinating! Makes sense, too...

</comment><comment><USER11> Dice, not dices!

<comment><USER12> unless you are referring to multiple sets of distinct dice.

</comment></comment><comment><USER13> The long dice would be familiar to most Tamils though, not unusual at all.

[https://tamil.boldsky.com/img/2020/01/1-dayakattai-157828523...](https://tamil.boldsky.com/img/2020/01/1-dayakattai-1578285237.jpg)

</comment><comment><USER14> > they found a set of roman dice for a game

mono-polis?

</comment><comment><USER15> It was Diplomacy. They still haven't finished the game.

<comment><USER16> Very nice observation

</comment></comment><comment><USER17> Not in original packaging?? Worthless!</comment>


Ask HN: Any startups working on clojure and Bitcoin/Ethereum? - <AUTHOR> Trying to find if clojure is getting used by blockchain startups? <comment><USER2> Found very interesting project/company [https://github.com/status- im](https://github.com/status-im) which is doing almost everything in Clojure and ClojureScript plus Go.

I track open positions from time to time on next website [https://blockchain.works-hub.com/](https://blockchain.works-hub.com/).

<comment><USER3> Except everybody hates Status for their terribly executed ICO which basically DoS'd the whole Ethereum network.

<comment><USER4> Everyone doesn't hate Status. They're one of the most serious outfits in the space, with alpha software already released and a solid roadmap.

<comment><USER5> Yea, but still, there is a bubble inside a bubble.

</comment></comment></comment></comment><comment><USER6> Why narrow it down to Clojure? Feels a tad artificial to me.

AFAIK, any Dapp using Ethereum has to make use of their JSON-RPC interface, which is language-agnostic. So it's perfectly fine to build a Clojure application on Ethereum, although there is a wrapper library for the JSON-RPC interface available in Javascript. No idea how many startups, if any, are using Clojure and for what reason.

<comment><USER7> > Why narrow it down to Clojure? Feels a tad artificial to me.

Maybe because he is "trying to find if clojure is getting used by blockchain startups?"</comment></comment>


Winning the Battle for Riddler Nation; an Agent-Based Modelling Approach - <AUTHOR> https://ntguardian.wordpress.com/2017/05/29/winning-the-battle-for-riddler-nation-an-agent-based-modelling-approach/ <comment><USER2> PSA: FiveThirtyEight are running the problem again [1], and this time have released the data from the previous battle so you can see the soldier distributions that everyone took last time [2]. Submissions are due this Friday.

[1]: [http://fivethirtyeight.com/features/the-battle-for- riddler-n...](http://fivethirtyeight.com/features/the-battle-for-riddler- nation-round-2/)

[2]: [https://github.com/fivethirtyeight/data/tree/master/riddler-...](https://github.com/fivethirtyeight/data/tree/master/riddler- castles)

<comment><USER3> aw, the submission form says "Use this form to submit your strategy for the May 19, 2017, Riddler by 11:59 p.m. EST on May 28, 2017."

:(

</comment></comment><comment><USER4> This was a fun problem. I wish I spent a little more time on it. My solution and approach was pretty similar to the OP, code and write up here: [https://github.com/mattdodge/538-riddler- nation](https://github.com/mattdodge/538-riddler-nation)

The biggest takeaway I think is that you don't even need to beat the "winning solution", you need to beat more of the general population than that solution does.

<comment><AUTHOR> Damn, yours beats mine. :(

<comment><USER4> Haha, but that doesn't matter! You just have to beat more other people than I do.

</comment></comment></comment><comment><USER5> I wish I read The Riddler more regularly—this is a really interesting problem, and I'm sorry I missed the contest!

<comment><AUTHOR> The contest might be still on. The guy running it took a week off.

</comment></comment><comment><USER6> Responsive PSD To WordPress Conversion Services Company in India. MarkupBox provides expert WordPress theme Conversion Services at affordable rates. [https://www.markupbox.com/psd-to-wordpress/](https://www.markupbox.com/psd- to-wordpress/)</comment>


How Shopify implemented its secure authentication service - <AUTHOR> https://engineering.shopify.com/blogs/engineering/implement-secure-central-authentication-service-six-steps <comment><USER2> So is Shopify the biggest fish still on the Ruby stack? Nice article detailing how they did an upgrade to openId connect to allow SSO on multiple shops within a client company.

<comment><USER3> IIRC there are still many large companies using Ruby/Rails still, they've just also diversified their tech stacks (as larger companies tend to do). AFAIK the list includes: GitHub (MS has a few Rails-based acquisitions now), Airbnb, Groupon, Square, Cookpad, Kickstarter, Hulu, etc..

<comment><USER4> Pretty sure Stripe is a Ruby shop as well.

<comment><USER5> One of the biggest. They recently released Sorbet, a gradual type checker for Ruby.

<comment><USER2> I sometimes forget how vast and diverse the whole industry is, so many tech. stacks and ecosystems.

</comment></comment></comment></comment></comment><comment><USER6> It's not mentioned but I'm assuming that they built their own OIDC/OAuth backend and not use existing ones (eg okta, Auth0 etc).

It would be interesting to know the details of how they're doing authorization. It appears that it's all or nothing but I might be mistaken.

<comment><USER7> Running an OAuth2 server isn't tremendously involved. There are good open- source projects like [https://github.com/ory/hydra](https://github.com/ory/hydra) that are pretty easy to configure.

<comment><USER8> Oh god, at megacorp we implemented our own OAuth2 stack. Much sadness ensued.

<comment><USER9> Been there, done that - wish it upon no one.

If anyone ever brings up the idea of building out oauth or even vaguely user management, I try to point them to at least try a POC (Proof of Concept) with [https://www.keycloak.org/](https://www.keycloak.org/) (Apache 2.0 License) or [https://www.gluu.org/](https://www.gluu.org/) (MIT License) before they considering building.

<comment><USER10> Another solution is OpenLDAP (or JumpCloud) at the root and then supporting software:

      OpenLDAP

       ├── PrivacyIDEA (TOTP/MFA with LDAP auth backend)

       ├──---└──  SAML iDp (e.g. SimpleSAMLphp or Shibboleth) for SSO: AWS, Google, Github, Atlassian, Snowflake, Azure etc.

       ├── Dex (https://github.com/dexidp/dex) for anything that wants Oauth flow

       ├── Native LDAP for apps that support it (e.g. Metabase, Grafana)

       ├── Any other custom authT that supports LDAP as a backend

OpenLDAP itself isn't for the faint hearted but I've had a lot of success with JumpCloud (and Okta also have an LDAP directory service... though starting price is high).

<comment><USER6> I don't think anyone building a modern identity solution should base it on openldap. LDAP is amazing as an identity provider in a data center, but does not offer support for modern authentication methods like oath and oidc. As such, it's not a very good base for creating your organizations identity.

I'm happy to be proven wrong about this. I love open standards and protocols.

<comment><USER11> > LDAP is amazing as an identity provider in a data center, but does not offer > support for modern authentication methods like oath and oidc.

I don't think lack of support for OAuth is a problem here. OAuth is specifically designed to obtain access to an HTTP service[1], and OpenID Connect is specifically designed for OAuth. LDAP is not an HTTP service.

[1]: [https://tools.ietf.org/html/rfc6749](https://tools.ietf.org/html/rfc6749)

</comment></comment></comment></comment></comment></comment></comment><comment><USER12> Well design of one-to-one relationship between users and shops. Then, they solve the problem that approach has brought. Nothing particular at the article.</comment>


CoinJack – Don't block web miners, control them - hans-strudle https://github.com/hans-strudle/CoinJack <comment><AUTHOR> So, I didn't realize coin miners are using peoples' browsers like this until Strudel sent me a link to his repo. I wonder how people feel about this; is it ethical?</comment>