Dell XPS 13 Kabylake Makes for a Great Linux Laptop - <AUTHOR> https://www.phoronix.com/scan.php?page=article&item=dell-xps13-9370&num=1 <comment><USER3> > There is, of course, the Dell XPS Developer Edition models that come > preloaded with Ubuntu 16.04 (or just in the past few days, Ubuntu 18.04). > Though for my purposes I went with the Dell XPS 13 preloaded with Windows 10 > due to running some benchmarks there prior to wiping the disk, faster > shipping time going from B&H Photo Video over Dell.com, and running Fedora > Workstation as my preferred main OS rather than Ubuntu.

Unfortunately, from what I've been told by one of the guys in Dell's Sputnik program, they gauge interest on the Linux Dell laptops _strictly_ by the number of people who buy Developer Edition laptops. So the author is not helping the cause by buying a Windows 10 laptop and loading Linux onto it.

Believe me, I get it. The Windows ones go on sale, while the Developer Editions pretty much never do. I'm guilty of buying a Win10 one myself before this was explained to me. Just passing that info on. If you want to support the future of Linux on Dell laptops, I strongly urge you to buy the ones with Linux pre-loaded, from Dell.

<comment><USER4> Do you know what the best way is to get my hands on one in the EU, preferably with a US keyboard layout?

<comment><USER5> Dell offer a choice of local or US keyboard:

[https://www.dell.com/en- uk/work/shop/laptops/xps-13-9370-lap...](https://www.dell.com/en- uk/work/shop/laptops/xps-13-9370-laptop/spd/xps-13-9370-laptop?~ck=bt&appliedRefinements=301)

This is probably a better plan than importing something without paying taxes. If Brexit happens, there's still Ireland for an English Dell website in the EU.

(Like most other European layouts, the British/Irish one will mean the ISO layout rather than the American (ANSI) layout. Other than the additional key giving space for £ and ¬, there's not much difference; so you might prefer that if you want to keep a vertical-shape enter key.)

<comment><USER4> There's a 9370 on mindfactory.de, doesn't say it's the dev edition, but the os is specified as Ubuntu. And the exact configuration I want, i7 16/512 FHD. The price seems ok, the only flaw being the german layout with the vertical enter key.

</comment></comment></comment></comment><comment><USER6> About a year ago I was looking to upgrade from my Thinkpad x220 and I ended up with an XPS 13 9360, a year later am comfortable saying it's the best laptop I've ever owned by a long shot. For my personal DD I like to use Arch and I've discovered basically no "linux-y" issues unique to the laptop hardware. Battery life is impressive, usually lasting 8+ hours of web browsing/casual usage with no tweaks (imo usually linux sees a much larger drop off). I'm definitely glad I went with the 1080p version, the PPI is already very high with such a small screen and I think the touchscreen/4K would have been overkill. Build quality is great and the laptop has a super premium feel. I know others have complained about build issues, I guess to them I would just repeat the old adage that you only hear about the people with issues, never from the satisfied users.

I would also say that the newer ones with multi-core are probably not worth the premium, if you can get last year's model for a good price then go for it. I got mine for $850 brand new, a few months before the multi-cores were announced. I don't think I really missed anything.

<comment><USER7> I'd like to try the new multicore from Intel. The dual core with HT on my XPS 13 is total trash when throwing at it more than a couple of tasks. And I am not the only one with this issue at work where we use a mix of Fedora 27/28 and Ubuntu 17.10/18.04. The only redeeming aspect of this otherwise overprices machine is the screen. Although I just wished the screen would be flushed with the bezel like for the touch screen version.

</comment></comment><comment><USER8> I used Linux for 10 years (mainly on Lenovos and some early Dell XPS back in the days), then I switched to MacOS about 3-4 years ago and over the last couple weeks I have been trying to go back to Linux because I am sick having to use MacOS everyday. It is a great OS for an everyday user, but not for a developer.

Here is what I tried so far:

1) Dell XPS 9370 Developer edition: This comes preloaded with Ubuntu and it is actually amazing that everything works out of the box. It was too small for me though, and the fan made a rattling noise so I decided to return it. The 4K screen is probably overkill on such a small display. Based on the review people recommend taking the normal screen, it saves a lot of battery and there is not that much difference.

2) Lenovo X1: I didn't like the feel of the Keyboard, and the screen was not that good. Installing Linux (Arch) was easy, but decided to return it.

3) Dell XPS 9570: I have this one for the last two weeks and so far I love it on the hardware level. I would even put it as somehow superior to my MacBook Pro. The downside is that Linux is not well supported at all. I have installed Arch so far and spent all my evenings trying to fix all the drivers. So far: The Nvidia drivers are barely working, ACPI needs a lot of tweaks (but it seems I got it working and got my 7 hours of battery). I still need to work on the Touchpad, and couple other things.

So far, the Dell XPS 9570 is a good challenger to the MBP, but installing Linux is still going to be a small challenge

<comment><USER9> > I am sick having to use MacOS every day. It is a great OS for an everyday > user, but not for a developer.

Could you expound on that? I'm curious as to why OS X isn't satisfying for you as a developer.

<comment><USER10> A lot of the GNU userland used in macOS is _ancient_ I think this is partly due to new GPL3 incompat? Then the BSD userland is _also_ ancient... for no apparent reason... Then there is no native package manager, so you have to use stuff like brew - which kinda sorta works but doesn't really feel anywhere near as consistent, integrated and up do date as basically _any_ linux package manger.

Then there's MacOS itself... which is just getting more annoying, I quit after 10.6 (which was best version IMO), everytime I use a mac now I compare it to the relative simplicity and stability of this version, and it's just so much worse. I'm sure others who have more experience with up to date MacOS can give more detail on this.

That said, for non developers I'd still recommend a mac over windows, although in recent years it's gone down hill, and personally I don't want to trade my freedom for closed source OS that have their own agenda - I understand that most users don't have the luxury of really being able to use anything not as friendly to basic users.

<comment><USER11> on the other hand some of the problems you mentioned were solved on Windows with WSL.

<comment><USER10> WSL is not a good solution from what i've seen, most of it's proponents have never used Linux on real hardware and are comparing it to gitbash for windows or whatever, or have never used linux before. Some things run fine, others are insanely slow due to either slow translation layer or simply because the behaviour of the underlying windows kernel actually is really many times slower than linux, e.g forking - I didn't know this, just found out first hand. The file-system integration is a bag of shit - the common issue being trying to use git in linux while editing files from a GUI in windows will cause frequent explosions, failed fs updates to to arbitrary windows locking are not fed back to linux which really fucks with git. (i'm talking about using the linux fs from windows which is the way with the least issues - <USER2> the reverse has even more severe consequences). Also the terminal app is the worst i've ever seen. FYI I'm talking from experience helping my colleagues who use windows. </rant>

IMO, if you must use windows and need linux/gnu stuff, just stick linux in a VM with a full GUI, it may seem more resource intensive running a whole other kernel and GUI, but it will work reliably without horrible surprises.

</comment></comment></comment></comment></comment><comment><USER12> If you want to use NixOs: [https://gist.githubusercontent.com/Ortuna/b6e95d6baefd2a1683...](https://gist.githubusercontent.com/Ortuna/b6e95d6baefd2a1683ddd848f485bf00/raw/94331b994bc7d73a762d177d1605115443d7a786/configuration.nix)

\-- with the latest kernel, even the webcam is working now (the only thing that didn't).

</comment><comment><USER13> I have been using Linux on servers since 1993. I have been dual booting SUSE with Windows 2000 on my desktop between 2000-2004. Ubuntu and then Arch has been my daily driver 2004-2017. I am not exactly a Linux newbie. But, based on these long, long years, I swear Linux desktop advocates have Stockholm syndrome. Some experiences: Samsung stopped making drivers for their MFCs so I needed to toss a perfectly working laser MFC because it stopped working with Linux, just like that. Later, a HP MFC caused endless pain, seemingly every other Arch update broke one of Bluetooth / printer of MFC / scanner of MFC. Plain Wifi eventually worked more or less (but see the endless string of bugs with 5GHz) but enterprise wifi always has been a pain. The strange F5 VPN our company used was not particularly Linux friendly -- I could only get it to work by running Firefox as root (yuck!). The only reference to the entire shebang was our IT asking around on various forums how to get it work under Linux and noone answering. And then Firefox stopped supporting extensions and I needed to tether my phone to get on the VPN. We now have a different VPN, no idea about the Linux support.

I am now using Windows 10 with the Linux Subsystem. O&O shutup takes care of the privacy concerns. I have a Lenovo Graphics Dock and docking and undocking is a nonevent. Do you want to be the one who gets an nVidia GPU hotplugging working on Linux -- and keeps it working through all the improvements the Linux desktop goes through? Worse, get IOMMU passthrough working with this setup because most of the games are still Windows only? I don't, that's for sure. I am 43 years old today and there is not enough time left to use a tamagotchi OS. The Linux Subsystem could have a better I/O performance but I will live. It's a surprisingly frustration free life. Some useful configuration tips [https://github.com/chx/chx.github.io/wiki/How-I-set-up-my- Wi...](https://github.com/chx/chx.github.io/wiki/How-I-set-up-my- Windows-10-\(coming-from-Linux\))

Before you inevitably downvote this, please comment where I am wrong. If you feel all the above are trivial, give me an offer for maintaing my Linux, I would actually love to get back there but for the time being I do not feel I can. I yearned for someone to take over desktop sysadmin from me for many years but I absolutely couldn't find anyone so eventually I just gave up.

<comment><USER14> > Samsung stopped making drivers for their MFCs so I needed to toss a > perfectly working laser MFC because it stopped working with Linux, just like > that.

Erm... The old drivers stopped working with this particular device?

I had a very similar case with perfectly good HP laser printer, which doesn't work on Window 10 anymore because... dunno? No drivers from HP, though. I'm sure it would work just fine with generic PCL or PostScript driver under CUPS.

> Later, a HP MFC caused endless pain, seemingly every other Arch update broke > one of Bluetooth / printer of MFC / scanner of MFC.

Well, that's probably self-inflicted because of your choice of Arch, not because Linux (e.g. Debian).

> Plain Wifi eventually worked more or less (but see the endless string of > bugs with 5GHz) but enterprise wifi always has been a pain.

Enterprise Wi-Fi has always been a pain, also under Windows.

> The strange F5 VPN our company used was not particularly Linux friendly

VPNs are usually that way. Very few companies can write sensibly working software that would run under Linux.

> \-- I could only get it to work by running Firefox as root (yuck!).

You get pretty much the same under Windows, though you don't see it as clearly.

I don't get why you bash Linux. Windows has the exact same problems.

<comment><USER13> > Erm... The old drivers stopped working with this particular device?

Samsung simply stopped producing Linux drivers. Indeed if you look at [https://www.bchemnet.com/suldr/index.html](https://www.bchemnet.com/suldr/index.html) there is more than a few years gap here. Also, if you look at the newer drivers support page now that some models have maximum support versions [https://www.bchemnet.com/suldr/supported.html](https://www.bchemnet.com/suldr/supported.html) where I persume you are ... if you update -- and "obviously" you can't not to update because eventually some API breaks the driver. My printer broke in 2010 with an Ubuntu update.

> Very few companies can write sensibly working software that would run under > Linux.

Which is the problem itself. You got it in one.

> You get pretty much the same under Windows, though you don't see it as > clearly.

It's possible I do not see it clearly but the only Bluetooth problem I had was the April Creators update mysteriously changing Chrome to use the internal soundcard which was solved in two clicks in Eartrumpet (which was new to me -- finding that software took a little time). I have yet to meet any of the problems listed: every wifi and VPN I have yet seen have Windows support (and IT is so much more prepared to help if there is a problem), the Bluetooth stack actually didn't break, nor have Windows upgrades haven't broken my MFC yet (although I guess I need to wait -- but how long? I have seen people install HP LaserJet 4 on Win 10 with some struggle). And as I mentioned, my Thunderbolt eGPU just works. Are you saying it would just work on Linux...? Come now.

I love Linux to pieces and I run it on servers and use the userspace components still but I am writing to warn people: it is still not the year of Linux on desktop and probably never will be. Or, if you so prefer, it finally is, it's just Linux on the Windows desktop.

</comment></comment></comment><comment><USER15> I have a Dell XPS 13 and it's fantastic. I'm running Ubuntu 18.04 on it. I've run into typical issues with UEFI vs BIOS and problems with Secure boot, but that's typical of nearly every new laptop nowadays. Had problems with Manjaro running KDE dropping bluetooth connections, but Ubuntu 18.04 runs great.

</comment><comment><USER16> I have a thinkpad T470(Fedora 28) and T470p(QubesOS) that runs Linux just fine. Without any driver issues. The battery life is excellent once you install the tlp packages.

</comment><comment><USER4> Too bad its 16:9 aspect ratio gives you less screen real-estate than the macbook pro 13.

</comment><comment><USER17> But did they fix the coil whine?

</comment><comment><USER18> FYI: 9370 has _smaller_ battery than 9360 while having same panel and most of internals

</comment><comment><USER19> The performance seems great in comparison. But this laptop seems a bit thin for my taste. There would be room to almost double the battery if the thickness was increased. There would also be room for USB-A and a LAN port. Two things I would really like to see.

Also I read a lot of bad experiences here on HN with the XPS line every time it comes up. Personally I know at least two people who had a bad experience with it and ended up replacing the machine with something else. Is Dell improving on that part or has it stabilized?

On paper the machine looks really good but right now I just can't justify pulling the trigger to replace a Retina-MBP.

<comment><USER20> > Also I read a lot of bad experiences here on HN with the XPS line every time > it comes up. Personally I know at least two people who had a bad experience > with it and ended up replacing the machine with something else. Is Dell > improving on that part or has it stabilized?

Haha, yes, I'm one of the unfortunate people that use XPS 13 9350 and have had a lot of issues with it. On the other hand I installed Arch recently and everything works out of the box, including touch screen, that really surprised me.

Personally I would blame Intel for their crappy hardware (all issues were with Intel peripherals), but that's me.

</comment></comment><comment><USER21> I have the previous model, the 9360, and my only real complaint is the touch pad. Palm rejection is just terrible, so much so that I've considered just turning off the touch pad and using a mouse.

One nice feature of the touch pad is that the scrolling direction for the mouse is independent of that for the touch pad. This means I can set the mouse to work like mice always have, before Apple invented "natural" scrolling, but have the touch pad use "natural" mode. For some reason, this actually feels right to me. I wish my Macbook Pro could do this.

<comment><USER22> I haven't used it but try:

"Scroll Reverser is a free Mac app that reverses the direction of scrolling. It is available for macOS 10.4 through 10.13.

It has independent settings for trackpads, mice and Wacom tablets, and for horizontal and vertical scrolling. "

[https://pilotmoon.com/scrollreverser/](https://pilotmoon.com/scrollreverser/)

<comment><USER23> I've been using this for a while now, and it has been a godsend.

That said, I do consider it a ding against MacOs, because it's ridiculous that I'm forced to use third-party tools for such basic functionality. (Other examples: USB-tethering with non-Apple phones requires hunting down and installing third-party drivers. A feature that just works, out-of-the-box, on every other system I've ever used.)

</comment></comment></comment><comment><USER24> Personally, my 9350 has me never wanting to own a Dell again. Touchpad alone.

<comment><USER25> Same here, I am still pissed because of the flicker issues I have with the screen of my XPS 15 9530 and today I saw that the builtin battery is down to 70% of its original capacity.

Sure, they look pretty and the Linux support is good, but the build quality didn't satisfy my expectations.

</comment></comment><comment><USER26> I use middle click to paste all time and it's one of the reasons I bought only laptops with 3 hardware buttons on the touchpad so far. How does middle click work with the kind of touchpad on the XPS?

<comment><USER4> Seriously, why not learn keyboard shortcuts? Strange to depend on such an idiosyncratic feature.

<comment><USER5> > "You're holding it wrong"

Many people select text using the mouse, then reposition the cursor using the mouse. It's convenient to then insert the selected text using the mouse — the entire operation is done without touching the keyboard.

</comment></comment></comment><comment><USER27> Nobody sell my ideal laptop.

It must have 15 inch Builtin 4K display, Ethernet, display port, multiple USB ports and No Nvidia GPU.

I usually don't move my laptop so I prefer 15 inch over 13 inch. But I like my primary computer ready to be carried anywhere so I don't want desktop.

I don't play video game or graphics on my primary computer so I don't need a dedicated GPU. Also Fuck you Nvidia.

There are 13 inch laptop which satisfy everything else or 15 inch with Nvidia GPU. I guess there is not much demand for my ideal.

<comment><USER28> Why Nvidia hate?

<comment><USER29> If OP is at all involved in using or developing for Linux, it seems justifiable... Their approach to linux support has been anything from "poor" to "outright hostile" for a long time. AMD and Intel do a far, far better job of enabling and contributing to open source development and drivers, using standard kernel APIs, etc.

<comment><USER30> But my deep learning...

As in, Nvidia's support for deep learning in linux is very good.

<comment><AUTHOR> AFAIK is deep learning the only reason to consider Nvidia at Linux. But if you do deep learning there is very little alternatives to Nvidia.

</comment></comment></comment></comment></comment><comment><USER31> Other than its weird webcam location, it looks great.

</comment><comment><USER32> One problem I have with my XPS 13 is the keyboard. It's too small for me to type without making lots of errors (I'm used to the size of keyboards on 14 inch laptops and full size pcs). Also the feel of the keys has no click and feels stiff. I often don't push the left shift properly due to the stiffness.

</comment><comment> blubb-fish two of several appeals of Linux to me are the fact that it is free and modest on resources.

from that angle it seems slightly ironic that all those great Linux laptops leave the 1000 usd mark way behind them.

thing is, I'm actually intending to buy a laptop and have Mint run on it.

any suggestions for a laptop cheaper than 1k?

I'm eyeing Dell latitude 5480.

<comment><USER33> I bought a used acer from 2012 and the only bad thing is battery life of around three hours. Can't imagine paying for a new laptop

<comment> blubb-fish i had very bad experiences 1st and 2nd hand with Acer, though. unprovoked crashes, WiFi not working without significant research and fiddling. multiple models.

</comment></comment></comment><comment><USER34> The Dell XPS 13 is what a mac book pro is supposed to be.

</comment><comment><USER35> Except for the 16:9 screen. I'm so done working with such a narrow aspect ratio.

<comment><USER36> Everything old is new again: [https://i.ytimg.com/vi/D_Lka7Tsmkk/maxresdefault.jpg](https://i.ytimg.com/vi/D_Lka7Tsmkk/maxresdefault.jpg)</comment></comment>


Ask HN:What are the best online resources to learn Python? - <AUTHOR>

I am starting to learn python and there are a ton of resources. I kind a got overwhelmed with all the available sources. What are the best ones according to you? <comment><USER2> In my opinion the best place to start is the tutorial on python.org, for whichever version of python (2 or 3) you are learning.

Python 2: [https://docs.python.org/2/tutorial/index.html](https://docs.python.org/2/tutorial/index.html)

Python 3: [https://docs.python.org/3/tutorial/index.html](https://docs.python.org/3/tutorial/index.html)

Also start browsing through the modules listing, so that you don't reinvent too many wheels:

Python 2: [https://docs.python.org/2/py- modindex.html](https://docs.python.org/2/py-modindex.html)

Python 3: [https://docs.python.org/3/py- modindex.html](https://docs.python.org/3/py-modindex.html)

And the answer to whether you should learn 2 or 3 is:

2, because there are still 3rd party tools that don't support 3. Or because your friends are using 2.

Unless you know you need 3.

Or if all your friends are using 3 (because that's where a lot of your help is going to come from).

[https://wiki.python.org/moin/Python2orPython3](https://wiki.python.org/moin/Python2orPython3)

But it doesn't matter overly much. Unless it does, for your job, but then they'll tell you.

<comment><AUTHOR> thanks @a3n. this is really helpful

</comment></comment><comment><USER3> Two words: "Python Koans".

Basically, these are coding exercises (floating about in various forked versions) that do a pretty good job at testing your working knowledge of core syntax (much better than staring at online tutorials, anyway). Including, importantly, a lot of the fussy stuff you don't think you need to be familiar with, but actually, you do (and would probably neglect entirely if you tried to sharpen your skills just by working on personal projects, thinking in terms of the idioms of whatever language you were most recently working with).

Just find a good weekend, roll up your sleeves, and push yourself through them. No one will be able to kick sand in your face in an interview or a phone screen ("What? You don't know about named tuples?") ever again.

<comment><AUTHOR> Thanks @dreamweapon. I like the hands on approach.

</comment></comment><comment><USER4> How to Think Like a Computer Scientist Learning with Python: Interactive Edition 2.0

[http://interactivepython.org/runestone/static/thinkcspy/inde...](http://interactivepython.org/runestone/static/thinkcspy/index.html)

<comment><AUTHOR> @Jimmahoney thanks. Just browsed through it. It's an interesting approach.

</comment></comment><comment><USER5> This post has been viewed 100,000+ times:

[http://codecondo.com/10-ways-to-learn-python/](http://codecondo.com/10-ways- to-learn-python/)

the absolute essential starting point for any want-to-be developer.

</comment><comment><USER6> One that hasn't been mentioned yet is [http://www.pythonchallenge.com](http://www.pythonchallenge.com), where answering each challenge correctly leads you on to the next one.

</comment><comment><USER7> Tutorial on python.org is by far the best If you are looking to start from the very basics, [http://www.tutorialspoint.com/python/index.htm](http://www.tutorialspoint.com/python/index.htm) explains with very easy examples

<comment><AUTHOR> @patriksaha thanks for sharing this with me

<comment><USER7> Cheers

</comment></comment></comment><comment><USER8> Learn by example with Real Python - [http://realpython.com](http://realpython.com)

(I am the co-founder)

<comment><AUTHOR> @mjhea0 thanks. That's interesting. Will definitely take a look at it.

</comment></comment><comment><USER9> [http://pythontutor.com/](http://pythontutor.com/)

<comment><AUTHOR> @ASquare thanks for your recommendation.

<comment><USER9> Cheers!</comment></comment></comment>


News for the tz database - <AUTHOR> https://github.com/eggert/tz/blob/master/NEWS <comment><USER2> One of my favorite surprising corners of the internet is the tz mailing list, where updates to the tz database are actively discussed:

[https://mm.icann.org/pipermail/tz/2018-July/thread.html](https://mm.icann.org/pipermail/tz/2018-July/thread.html)

The amount of effort and detail that goes into this database is astonishing - every few days there's a new twist introduced by timezone legislation somewhere around the world.

Even more impressive is their dedication to building a correct database of historic timezone changes - here's a post where someone submitted further details on the history of time in Macau for example: [https://mm.icann.org/pipermail/tz/2018-May/026467.html](https://mm.icann.org/pipermail/tz/2018-May/026467.html)

</comment><comment><USER3> This is like catnip to me. There's a tiny little critical corner of the Internet where dedicated volunteers bust their tails to make sure they get the details excruciatingly correct.

It's also a useful reminder to never, ever attempt to do datetime math on your own. _Always_ use a library! And if that library is buggy, submit patches but _don 't_ say "aww, I'll just do it myself".

</comment><comment><USER4> And while we cherish the work of volunteers maintaining this database, let's not forget that this database was once the subject of a meritless lawsuit: [https://www.eff.org/press/releases/eff-wins-protection- time-...](https://www.eff.org/press/releases/eff-wins-protection-time-zone- database)

<comment><USER5> The statement from the accuser was refreshing though:

In a statement, Astrolabe said, "Astrolabe's lawsuit against Mr. Olson and Mr. Eggert was based on a flawed understanding of the law. We now recognize that historical facts are no one's property and, accordingly, are withdrawing our Complaint. We deeply regret the disruption that our lawsuit caused for the volunteers who maintain the TZ database, and for Internet users."

</comment></comment><comment><USER6> They're removing East Saskatchewan? That was my favourite nonsense time zone. They're right that it should have been "West Saskatchewan", but I suppose Saskatchewan on its own is enough for the province outside Lloydminster, and Lloydminster uses Alberta (Mountain) time anyways which makes a second Saskatchewan timezones redundant (for now).

</comment><comment><USER7> Amazing work I take for granted. Thank you to all the maintainers and contributors!

</comment><comment><USER8> >>> zic no longer outputs a dummy transition at time -2 __59 (before the Big Bang), as clients should no longer need this to handle historical timestamps correctly.

Ok, when we consider events prior to the Big _freaking_ Bang as historical, _and_ have test code for it, then I feel we are in safe hands.

Keep up the good work folks :-)

</comment><comment><USER9> Does every Docker container, snap, flatpack etc. need to be updated every time the tz database releases a new update? Do they?

<comment><USER10> It is not necessary. Various backend systems can store dates and times as UTC, or UTC + time zone offset, and these cover the most common use cases. You can use these formats to communicate with clients, and have clients do the conversion for you, for example, in a browser you can use Date.getTimezoneOffset. One good thing about this is that if the time zone data is incorrect on a client's device, there is a reasonable chance that the client's clock is also showing the wrong time anyway. Most client OSs are aggressively updated so this is mostly solved. The remaining problems are any systems that need to do calendrical math, for example, calendar programs.

In practice, however, people write bad date/time code often enough that it's a problem. I was recently using a client library that was completely broken if the client's system had a negative offset from UTC more than 1 hour.

At work we get emails if we leave any container running that was built too long ago (three months or something?)

</comment></comment><comment><USER11> Reading through this just underscores how ridiculous it is that UTC itself has leap seconds. The mapping between the clock and our labeling of the clock varies so often, who cares about whether the underlying clock matches the Sun to the nearest second at a physical location that few of us will ever visit?

<comment><USER12> Can we interest you in International Atomic Time? It is, after all, the Atomic Age. And the tz database does have "right" timezones.

* [http://cr.yp.to/libtai/tai64.html](http://cr.yp.to/libtai/tai64.html)

</comment></comment><comment><USER13> It isn't clear why Ireland would need a negative DST? Don't they also "spring forward and fall back"?

<comment><USER14> In the Summer they call their time "Irish Standard Time", which indicates that they view the summer offset as the standard one and they are using "winter time" [1]. It's just a matter of perspective.

[1] [https://en.wikipedia.org/wiki/Winter_time_(clock_lag)](https://en.wikipedia.org/wiki/Winter_time_\(clock_lag\))

</comment></comment><comment><USER15> > Use "PST" and "PDT" for Philippine time.

I wonder if this will break anything. Some systems make the bad assumption that timezone abbreviations are unique, e.g. when parsing dates.

<comment><USER15> And the "changes to past timestamps" is why you can't even store past events using Olson timezone names like America/Los_Angeles: you have to use UTC and/or timezone offsets like -0700.

[https://en.m.wikipedia.org/wiki/Tz_database](https://en.m.wikipedia.org/wiki/Tz_database) [https://news.ycombinator.com/item?id=10032498](https://news.ycombinator.com/item?id=10032498)

<comment><USER16> Is it not the opposite, though? If you need to store the fact that an important meeting took place in Los Angeles at exactly 4.00pm on a specific date, if you had used utc/offsets, it would look like the meeting took place at 3.59.50pm or whatever change was done to correct the tz data for historical timezones?

<comment><USER17> It really depends on the use-case. If you had a meeting at a specific wall- time you'll want the timestamp to change. If you recorded a timestamp for when something happened, the local time should change.

But you should under no circumstances record the offset. Record either a timestamp or local time + location.

<comment><USER15> I agree that systems should record times in UTC. But I'm talking about a more nuanced edge case: parsing user-entered date strings. If a user says "4pm Los Angeles", it could be ambiguous, and recording the offset is the only way to reliably disambiguate. See my reply above.

</comment></comment></comment></comment></comment><comment><USER18> > Use "PST" and "PDT" for Philippine time.

What about us in Pacific daylight time? Now our timezone acronym is ambiguous.

</comment><comment><USER19> Time (handling) sucks.

<comment><USER20> You should try non terrestrial software dev where time dilation has to be accounted for.

</comment></comment><comment><USER21> You linked to a copy embedded in pytz.

Upstream database is here:

[https://github.com/eggert/tz](https://github.com/eggert/tz)

<comment><USER22> Thanks, we've updated the link from [https://github.com/stub42/pytz/blob/master/tz/NEWS](https://github.com/stub42/pytz/blob/master/tz/NEWS).</comment></comment>


In major goof, Uber stored sensitive database key on public GitHub page - <AUTHOR> http://arstechnica.com/security/2015/03/in-major-goof-uber-stored-sensitive-database-key-on-public-github-page/

<comment><USER2> Uber needs to accept responsibility and live with their mistake.

"Intruders"? Uber gave their permission when they uploaded the key to a public service (...a key to a publicly accessible database, nonetheless). Doesn't matter if it was accidental...Uber doesn't have the right to inconvenience another company (GitHub) with a subpoena because of their own mistake.

</comment><comment><USER3> "The contents of these internal database files are closely guarded by Uber,"

Mmm, the evidence suggests otherwise.

</comment><comment><USER4> The thing that I find particularly notable here is not that they stuck the key on GitHub, but that they are trying to subpoena GitHub for a list of everyone who accessed the gists in question. If allowed to do that, then that sets a precedent that's worth considering...

</comment><comment><USER5> I don't get the dearth of coverage to this negligence. Company valued at $40B advertises it's crypto key and the world yawns.

</comment><comment><USER6> "Goof". Is that what they are calling this nowadays?</comment>


Scientists discover how to turn light into matter after 80-year quest (2014) - <AUTHOR> http://www3.imperial.ac.uk/newsandeventspggrp/imperialcollege/newssummary/news_16-5-2014-15-32-44 <comment><USER2> Since 2014 I can find 34 citations, none of which are an actual experimental realization of their scheme [1]. Anyhow,

TL;DR: They theoretically propose the following experiment:

First, accelerate electrons to just below the speed of light and fire them into a slab of gold. This creates the beam of nessesary high-energy photons.

Second, fire a high-energy laser at the inner surface of a tiny hohlraum (German for 'empty room') gold can, to create a thermal radiation field which generates light similar to that emitted by stars.

Finally, direct the photon beam from (1) through the centre of the can, causing the photons from the two sources to collide and form electrons and positrons. It would then be possible to detect the formation of the electrons and positrons when they exited the can.

===

[1] [https://www.researchgate.net/publication/270858006_A_photon-...](https://www.researchgate.net/publication/270858006_A_photon- photon_collider_in_a_vacuum_hohlraum)

<comment><USER3> I know it's from the article, but the expression "Accelerate Electrons just below the speed of light" tells you pretty much nothing. An electron travelling at .9 the speed of light has 1.1 MeV of energy.

Nature seems to be down, so I can't access the abstract, but the google tagline has the following.

'Photons emitted above 100 MeV as a function of target width, for 1 × 109 incident electrons of energy 500 MeV (blue), 1 GeV (black) and 2 GeV (red).'

A table for comparison

            .9    1.1 MeV
           .99    3.6 MeV
          .999   11 MeV
         .9999   36 MeV
        .99999  114 MeV
       .999999  361 MeV
      .9999999  1.14 GeV

So it's somewhere in the .999999c-.999999999c. Assuming that snippet was accurate. The LHC gets particles up to the TeV range, but, as the name suggests, they are much larger particles. An actual particle physicist can probably tell you more about whether it is significantly harder to get the much lighter Electron (and associated radiation losses) up to those energies.

SLAC ([https://en.wikipedia.org/wiki/SLAC_National_Accelerator_Labo...](https://en.wikipedia.org/wiki/SLAC_National_Accelerator_Laboratory)) apparently can get electrons up to 50 GeV, so if those energies from the snippet are the target ones, that part should be achievable.

<comment><USER4> I'm not a particle physicist but a particle accelerator engineer.

GeV energies for electrons are achievable with a reasonably sized synchrotron like Diamond Light Source[0]. The magnets required to keep electrons in line are quite a bit smaller than those required for protons due to the mass difference. Small refrigerator sized verses small car sized.

[0] [https://en.wikipedia.org/wiki/Diamond_Light_Source](https://en.wikipedia.org/wiki/Diamond_Light_Source)

</comment></comment></comment><comment><USER5> For a split second I thought, "well, can we even do the reverse?" Then I realized yeah, pretty much all light comes from matter. And a less useless question came to mind: Can light emerge from any source _other_ than matter?

I don't know. I'm no physicist, and it's not an area where I could even be mistaken for a knowledgeable amateur, and it seems like I'm asking "can a photon give rise to another photon". But it did lead me to a very interesting treatment of a _similar_ question concerning the _de novo_ creation of photons [0]

[0] [http://curious.astro.cornell.edu/about- us/137-physics/genera...](http://curious.astro.cornell.edu/about- us/137-physics/general-physics/particles-and-quantum-physics/805-how-are- photons-created-and-destroyed-advanced)

<comment><USER6> Depending on what you mean precisely, I'd actually say that most of our light sources other than the sun don't come from matter, in the sense that they don't turn matter into light but rather light is created when the energy level of electrons changes (whether in electric or chemical light sources).

Of course indirectly, this energy comes from matter being turned into energy, whether by the sun or by nuclear fission.

What I find more interesting is that today, all our energy ultimately can be traced back to stars, even if sometimes extremely indirectly (e.g. in the case of fossil fuels or nuclear fission). But this could actually change -- if nuclear fusion becomes used in practice.

<comment><USER7> > they don't turn matter into light but rather light is created when the > energy level of electrons changes (whether in electric or chemical light > sources). > Of course indirectly, this energy comes from matter being turned > into energy, whether by the sun or by nuclear fission.

This is incorrect. It directly comes from matter as the rest mass of the low energy state is a minuscule amount less than high energy state. Specifically it is E/c^2 less, where E is the energy of the photon.

<comment><USER8> Parent is talking about different processes that produce photons: classical acceleration of charged particles vs particle-antiparticle annihilation.

You brought in a fact from general relativity which has no bearing on which processes are more common in the universe.

Of course you can always be pedantic and analyze problems at the wrong level. For example, you can say it's all the same QED vertex in the end.

<comment><USER7> They are fundamentally the same mechanism by our current understanding of physics. It is not a pedantic point.

</comment></comment></comment></comment></comment><comment><USER9> They already discovered how 80 years ago. This is them theorizing that they can do it with modern technology.

TL;DR: They still cannot do it.

</comment><comment><USER10> This article started with such a bafflingly breathless tone about 80-year-old physics that I couldn't even finish it. Pair production is _not_ exciting or controversial.

<comment><USER11> Pair production usually can't happen unless an atomic nucleus is nearby. This is necessary for the conservation of momentum. I don't think photon-photon pair production has been achieved yet.

<comment><USER12> I believe you, but can you explain in more detail?

The classic diagram in undergrad physics is of a single particle going in one direction converting to two particle/antiparticle pairs going off at angles with a total momentum equal to that of the first particle. Why can that situation not happen?

<comment><USER13> That can't happen if the incoming particle is a single photon. One way to convince yourself is to realize that a closed system consisting of a single photon is massless, therefore it cannot later contain a massive particle without violating conservation of mass (in the sense of E^2 - p^2).

Another way to think about it is that a photon contains the maximum amount of momentum possible for a given amount of energy. (E = p). If you transform any of its kinetic energy into rest energy, there's nothing that can carry the excess momentum.

However if the photon is in the presence of a massive particle, that particle can soak up the excess momentum, and pair production is possible. Alternatively if you have two photons, their momenta can cancel and pair production is again possible.

A fun physics problem is a photon striking an electron and producing an electron-positron pair; what was the minimum energy of the photon, in terms of electron rest energies? It's not two, for the reasons given above!

<comment><USER12> Thanks, that makes sense.

</comment></comment></comment></comment></comment><comment><USER14> Read that entire article to find out what type of matter turned out...only to realize that they have not actually created anything, or run the experiment.

So, any idea what type of matter would it be created?

<comment><AUTHOR> >>electrons and positrons

<comment><USER14> dumb question: what happens to them? Suppose you get lots and lots of energy converted into electrons and positrons...do they go and forth with each other until they create something bigger? If so, what?

</comment></comment></comment><comment><USER15> To be fair it's more like "turn matter into light and then into matter", since they still need to accelerate electrons first to produce the gamma photons.

<comment><USER16> They're not turning those electrons into photons; they're using the electrons to transfer energy from the accelerator into gamma photons. The electrons aren't annihilated in the process.

<comment><USER2> Thinking about it, that would mean they emit some kind of Bremsstrahlung, or not? If that is the case, I am wondering about the angular distribution of the emitted gamma photons... I would consider it rather random. This would beg the question, how do you focus and direct the gamma beam into the gold can?

<comment><USER16> SLAC, at least, works by deflecting the electrons, rather than by slowing them down via Bremsstrahlung.

[https://lcls.slac.stanford.edu/overview](https://lcls.slac.stanford.edu/overview)

The result is a nice, tight, collimated beam of hard X-rays. Pretty awesome! But I'm not sure that SLAC has the power for this experiment - they probably would have done it already if they did...

</comment></comment></comment></comment><comment><USER17> I have a theory that it is possible to travel inside the light, most likely at close to the light speeds and travel thru universe literally on the beam of light scattering thru the space.

We know its possible for laser to have different spectrum and resonate with different speeds (imagine putting very close to each other million lasers and creating one large "tunnel", where outlayers vibrate at higher speeds thus creating "walls/ceiling/floor". That's probably the "easy" part. It might be super expensive in terms of used electricity to power such travel channel but tiny bits comparing to manned trip to Mars. Most likely the biggest problem here would be putting an object, or a person inside it and make it not accelerate to speed of light in split second (as light travels it creates a wave, similarly to a river creating stream and you getting in it are being pushed by it). The object put inside such laser tunnel (lets call it "lunnel") would have to be incredibly heavy so that it starts accelerating slowly and won't disintegrate hitting max speeds before reaching destination.

As a result of building such vehicle, imagine seeing a blimp or red light on the sky that least less than half a second. What happened? Oh, just another cargo delivery to Mars, no biggie.

One day I will write a paper on it, so it can bare my name.

<comment><USER18> The laws of physics and special relativity would like to have a... word... with you in the other room.</comment></comment>


India's injectable vasectomy - <AUTHOR> http://www.minnpost.com/globalpost/2011/07/13/29944/indias_injectable_vasectomy <comment><USER2> The most important thing about this news post has been left out of the title: it is completely reversible!</comment>


FBI secretly collected data on Aaron Swartz earlier than was thought - <AUTHOR> https://gizmodo.com/fbi-secretly-collected-data-on-aaron-swartz-earlier-tha-1831076900 <comment><USER2> Bad headline to IMO a much bigger story. Aaron's metadata was swept up in, apparently, an NSL grab of a massive trove of email headers from the University of Pittsburg.

A case ostensibly linked to "Al Qaeda" allowed the FBI claim they had a basis to request a massive dump of email metadata from the University of Pittsburg IT department. We don't know exactly how much data was collected, just that Aaron's email happens to be on Page 27 of an Appendix.

All this metadata is stored indefinitely and is accessible in the course of any unrelated investigation.

The legal standard the FBI has to meet to be able to NSL this information from a target is described as "a hunch".

<comment><USER3> The irony of the email header collection is that since this batch of headers is associated with an "al Qaeda" investigation, then since the content of the emails is unknown, suddenly anyone who shows up in the headers appears suspect, especially out of context in a future datamine. Even though presumably hundreds or thousands of email addresses were in this same dump, and maybe one was of interest to the FBI at the time, but they cast the net as widely as they're allowed.

<comment><USER4> It's called "making the haystack bigger" in relation to finding the needle in the haystack. In other words mass surveillance increases the noise rather than the signal, which we've always know it does. The government just doesn't care because in the end mass surveillance allows it to target anyone at will without real judicial oversight for each person being investigated.

</comment></comment></comment><comment><USER5> Never forgive MIT

<comment><USER6> It's not just MIT. The prosecutors are really the ones to blame.

<comment><USER7> Why does no one have the perspective that Aaron knew he was literally stealing, according to the law, and that subverting the law, even if non ideal, was HIS choice, and therefore the overly dramatic legal threats were invited by HIS actions. It's his fault, and he didn't own up to it, even though he meant well.

<comment><USER8> "Aaron knew he was literally stealing, according to the law"

He was? I may be misremembering, but I don't think that was the crime he was accused of. I believe the crime was bypassing access control systems.

And even that accusation seriously stretched credulity.

<comment><USER9> >And even that accusation seriously stretched credulity.

How did that accusation seriously stretch credulity? The technical means may have been simple, but it's unquestionable that he did so intending to circumvent access controls.

<comment><USER8> Because he was not engaging in the sort of activity that the law was intended to address.

</comment></comment></comment></comment></comment></comment><comment><USER10> One "great" thing about Trump taking office has been all of the sunlight on the FBI/DOJ abuses. We already knew these surveillance systems would be abused, and now we have many evidences of smoking guns. Unfortunately right now the only places picking them up are conservative researchers. Don't ask me why.

This quote is a verifiable fact and should frighten everyone:

> _We know from Collyers report the FISA-702(16)(17) process was > extraordinarily abused by verified "contractors" who had access to the FBI > /NSA database. The rate of abuse was 85%. Meaning 85 out of every 100 > FISA702 database searches were unauthorized and outside of compliance._[1]

It gets worse. The data was used/sold for political purposes by opposition researchers.

The whole thing stinks and it's not a partisan issue. Anyone that cares about this stuff should be rallying around this news and demanding more information. Parties aside, this is serious.

[https://theconservativetreehouse.com/2018/12/14/john- solomon...](https://theconservativetreehouse.com/2018/12/14/john-solomon- drops-a-tick-tock-bombshell-dia-holds-documents-that-can-exonerate- flynn/#more-157749)

<comment><USER11> > all of the sunlight on the FBI/DOJ abuses. We already knew these > surveillance systems would be abused

 _creates secret police_

 _secret police abuses citizens_

What a twist.

<comment><USER12> What was the point of your comment? To be smug? You just posted the equivalent of "hueh hueh and water is wet amirite?"

Let's have real discussions here.

</comment></comment></comment><comment><USER13> Wait, the FBI did something sketchy?

This should honestly come as no surprise to anyone paying attention. Protect yourselves folks, no one else will.

<comment><USER14> The more power an organization has the more scrutiny should receive. Power abuses need to be brought to light. This is how democracy works.

We can't ignore a problem just because "everybody knows".

<comment><USER13> 100% agreed. i don't think anyone should ignore it by any means. it's just that the FBI/NSA/etc seem to just keep doing it, which is why it shouldn't come as a surprise, they've been caught many times doing questionable data gathering.

</comment></comment></comment><comment><USER15> Threatening the status quo is a guaranteed ticket to that mad theater.

</comment><comment><USER4> Remember this article the next time the FBI argues for "more data access".

The FBI is already allowed to eat the fruit of the poisonous tree on a daily basis thanks to its expansive surveillance powers, and the vast majority of judges are clueless about it.

Obama's executive order days before he left office along with the recent renewal (and expansion) of FISA 702 now also allows all 17 enforcement agencies (including DEA, IRS, SEC, etc) to have the same type of access without a warrant.

Who knows how many decades will pass until all of this will be _properly_ challenged at the Supreme Court. It's why I've argued here in the past about US' necessity to create a "Constitutional Court" that wouldn't allow blatantly unconstitutional laws to become laws after Congress and the president pass them in their effort to gain more power and control over the population.

<comment><USER16> How does that not just become another check to balance in this bipartisan mess?

<comment><USER4> And what makes you think that the checks and balances you have now are "the right amount"? Does it feel that way to you right now or in the past few decades?

<comment><USER16> I really am open to listening if you have any tangible ideas on why more than 3 would fix or help deter bipartisanism overriding checks and balances

</comment></comment></comment></comment><comment><USER17> TL;DR: not so much "data on Aaron Swartz" as "metadata on Swartz's email correspondence, as part of an unrelated investigation". The amount of email addresses about which 'metadata' was collected was obviously quite large, so it would be a mistake to read anything of significance into the fact that Swartz's email was involved.

<comment><USER6> > The amount of email addresses about which 'metadata' was collected was > obviously quite large

This is the significance that should be read into it.

<comment><USER17> That's par for the course for the sort of investigation we're talking about, though. It's not a 'fishing expedition', it's just a practice that's narrowly tailored to try and figure out the structure of highly dangerous crime cells and networks, as well as the possible perpetrators involved. There's a bit of a scare about 'metadata' collection lately, but as a tool it does have its narrow uses.

<comment><USER18> Do you have any basis for your claims of "narrowly tailored" or are you just making up facts?

If it were narrowly tailored, the FBI wouldn't be able to access the information when conducting an investigation that would not have otherwise been able to obtain that information without a court order.

Additionally your attempt to justify why this is OK is also wrong, NSLs are not supposed to be used to investigate organized crime, but to investigate and prevent terrorist attacks.</comment></comment></comment></comment>


The Three Slide Rule - <AUTHOR> http://blog.jgc.org/2011/09/three-slide-rule.html <comment><USER2> jgc has two articles on the front page of HN, and both are sweeping generalizations that, in essence, miss the point entirely. In this one, about presentations, he fails to understand that _how_ you present is not to be separated from _what_ you present. I too have heard lectures where somebody reads from notes. They are often awful.

Without writing my own tome (which would obviously be flawed), I'll simply implore you to consider the following question when putting your presentation together: Are you trying to teach or to persuade?

If persuading, keeping it entirely verbal may be effective (if you are good at such things). However, if teaching, most evidence points to opening up as many sensory channels as possible to get the information across. Usually, that means verbal and visual.

The most important thing is to structure your talk so that the audience's mind is engaged. A simple trick to help is to ask questions (even if rhetorically), then reveal the answer.

In other words, it's _how_ you use the slides, not _whether_ you use the slides.

Same with pie charts, btw (the other offending article).

EDIT: emphasis

<comment><AUTHOR> The teaching vs. persuading argument is very interesting, and I'd urge you to write about these thoughts even if they are, to use your words, flawed.

<comment><USER2> Briefly, and off the top of my head, if you are trying to _persuade_ , you want people to only consider the information you present. You are trying to show people a single line of reasoning that leads to an outcome that, by the time you get there, will seem "obvious." It actually works in your favor if they can't keep all of the argument in their head, because then they'll only be focusing on what you are saying right now (and jumping to the conclusion you've compelled) and not looking for ways to examine the veracity or any limiting conditions of what you are saying.

On the other hand, when teaching anything with a conceptual framework (that is, not just showing people how to install Wordpress), it's good to show not only the result, or examples of "truth," but also counterexamples. It's often useful to help define a concept by also saying what it is _not_. You want people to see all of the evidence and to be able to provide their own reasons as to the conclusion. You are clear, open, and even emphatic about assumptions or limiting conditions (at least to the point where it causes no harm to leave out and would only increase confusion if included).

If you happen to be so lucky as to have a room full of people who all share the same conceptual framework and vocabulary, then standing up and telling a story can also be an effective teaching tool. Mostly, however, we are being introduced to the vocabulary as we are being taught, and multiple channels of reinforcement are very helpful.

<comment><USER3> I would argue that the kind of persuasion you can get with this technique is most often shallow and short lived. If you fail to make strong impressions, to stimulate emotionally your audience, and to give counterexamples, it's very difficult to create real changes in people's mind. Especially if you are talking about subjects that really matter to your audience.

<comment><USER2> I agree with your recipe in general, but the main point is that your counterexamples are selected to strengthen your main point, not to point out its flaws.

</comment></comment></comment></comment></comment><comment><USER4> Love it. However, I think that this does not apply to every situation. It's fine for presentations at conferences, or presentations designed to convince an audience of a certain view or standpoint.

But if you've been asked to research a set of options for viability, for example, things are different. You'll need bullet-points with highlights, tables with totals, and conclusions that summarize the main differences. Such things are very well presented with slides. I believe that this is the kind of stuff Powerpoint was originally invented for.

Similar stuff if I'm going to explain Coffeescript to a room full of C# programmers; I want examples, on slides.

There's probably more examples like these. The moment you want the audience to make up their own mind (which option do I prefer? do I want to use Coffeescript?), you need to present facts, not just a story. I strongly doubt just telling people how cool Coffeescript's => operator is will get the point across very well.

If my audience wants hard facts, I'm going to put it on slides, whether or not my CEO has a 3 slide rule.

<comment><USER5> > _It's fine for presentations at conferences_

Even then, the approach taken by Lawrence Lessig (hundreds of slides, very rythmic), makes the point across. Yet the slides alone are worth nothing without the presenter.

The biggest mistake is to think that the slides contain the message, a mistake often shared both by the presenter and the audience. How many times have I heard "can we get a copy of those slides?". If I ever hear this question it means I have failed as a presenter.

It's useless and missing the point to ask for the slides. Slides are not the vector of the argument, you – the presenter – are; Slides are merely here to outline the point.

Nobody reads the bullets _and_ listen to you at the same time. Nobody will read those tables projected on that small screen at a jittery resolution. It could be bogus data and no one would care yet their mind will focus on it instead of what you say. You built a table to compute a total, so only the total matters. Guess what? Just show the total. Your discourse will expose what the bullets say, your discourse will sum up what's in the tables. Then you nail it by showing the total slide. If people do want the table to check values then its place is not in the slides, it's in a report. A document with _content_ that you hopefully provide when it matters. Slides on the opposite should basically have a very low content ratio in contrast with your speech, or people will simply be distracted from you and read. Worse, they will unconsciously wonder why they're here listening to you when they could just as well read the content by themselves, and end up getting bored.

<comment><USER6> "The biggest mistake is to think that the slides contain the message, a mistake often shared both by the presenter and the audience. How many times have I heard "can we get a copy of those slides?". If I ever hear this question it means I have failed as a presenter." I can not agree more. A presentation must be a tool to support your ideas, your information, your thoughts. Not the way around.

<comment><USER7> I don't think it means anything at all. People mostly ask for slide decks out of reflex, often because they weren't paying attention because they know they can get the slides later on.

<comment><USER5> We live in the same world indeed, so imagine what it means to get out of the room _without having even remotely been asked the question_.

(ok this could mean you totally crapped out, but I guess you could tell the difference)

</comment></comment></comment></comment></comment><comment><USER8> If I'm presenting my research (which is what I do almost every time I present), then I need to do two things: teach the audience about what I did, and show it was worth it with performance results.

As dhimes points out, teaching is different than persuading. If I'm going to teach something, I need figures. Words alone are not enough. In high school and college, my teachers would fill black-boards with figures and equations while they explained things. The first thing my intro to physics professors would always do is draw a picture. That's what I'm doing, except I don't draw my figures one-the-fly as they did. Think about when you first learned the various sorting algorithms. Would you have understood them without watching someone work through examples, moving numbers around as the algorithm progressed? This is very much the same thing.

As for performance results, I need to show multiple graphs that test various aspects of the system to give the audience the impression that everything works as advertised. (Just an impression is enough - they'll read the full paper if they're interested in being thoroughly convinced.) Just showing the graphs isn't enough, of course. I always take the time to explain what the experiment was in the first place, what the axes are, what each plotted line means, and which direction is "good" (for example, if it's scale-up, high is "good"). Finally, in case none of that sinks in, I explicitly tell them, "What we learned from this graph is: ___."

These things are probably going to require more than three slides.

</comment><comment><USER9> If a presentation can be fit into three slides, then why use slides at all? At that point, it seems better suited to a one-page Word doc. To wit: one of the most effective short-form idea communication tools I've ever seen is the infamous "P&G Memo" used by Procter & Gamble. It's worth Googling, absorbing, and pressing into service. You'd be amazed at how pretty much any complex idea can be condensed into a single page -- not to mention how much more readily it will be received and digested, which is the entire point of communication.

As for Powerpoint and Keynote, reserve those for actual presentations (i.e., delivered live in front of an audience). Try to avoid them as handouts or passed-around documents, unless requested by the recipient (And even then, politely push back if possible; most people have been conditioned to ask for PPTs when they don't really need, or even want them).

<comment><USER10> The "P&G Memo" is very similar to Toyota's "A3 Process". The whole idea is to clearly and concisely explain (with visuals) a complex technical point. In Toyota's case it's so that at a meeting everyone can just spend a few minutes reading the report, instead of 30-60 minutes in front of a presentation.

</comment></comment><comment><USER11> I feel like slides should almost act like a prompt to me (the speaker) as opposed to presenting critical information. I am also a feverish believer that throwing out a huge amount of technical content in a presentation is (often, though obviously not always) pointless. Unless you're speaking to a _very_ specific audience, numbers should be presented in a graphical form which makes it easy to get the gist in a single glance.

This is just my experience, and admittedly is largely limited to the academic world, but when someone stands up and has a table with five columns, five rows, and numbers to eight significant figures I immediately switch off!

</comment><comment><USER12> I used to use powerpoint for my classes. A few years ago, something messed up, and I could only use the blackboard. Guess what? Best. Class. Ever. Now, my scheme is to teach the way people taught 100 years ago. I talk to my students. I write important things on the board (at, it should be said, the exact same speed as they can take notes). I have a stack of slides with illustrations of things that are too complicated to draw on the board, and I select from this stack occasionally. (Those slides are also on the course website, so students can print them if they want to insert them in their notes.) All of this works very well. At first, the students are freaked out by the fact that they have to attend class, and pay attention, and take notes. But, in the end, quite a lot of the class reviews point out that the blackboard is much better than powerpoint.

</comment><comment><USER13> A presentation is someone telling a story. it's an emotionel Endeavour, not a presentation of facts. if it was you could just write a report or send out a memo. As a presenter you need to bear this in mind.

Like any other story it should be engaging, interesting, fun and memorable. It should also have a beginning and an end. If you think of your slides in this context things change. Their goal is to amplify your point, make a technical point clearer, or something Else to underline what you're saying. The main focus should be the speaker, not the slides.

If you want to see a true Master look at some of Steve Jobs keynotes. There are three kind of slides:

\- pictures to show what the product looks like.

\- short bullets to give an overview (a phone, an iPod, an internet communications device)

\- simple graphs to show a point or a trend.

<comment><USER14> _A presentation is someone telling a story. it's an emotionel Endeavour, not a presentation of facts. if it was you could just write a report or send out a memo. As a presenter you need to bear this in mind._

Not always. For instance, a scientist gives oral presentations at conferences, and goes to see oral presentations by others, because verbal communication with visual aids is a more effective form of communication than written. I can get a better idea of what someone else is doing by having them explain it to me for ten minutes than by spending ten minutes reading their words on paper... even though I can read words far faster than they can speak 'em.

I hate being overwhelmed by slides, so I've tried adapting some of these sorts of techniques to scientific talks, but I just can't. I'm not selling something, I'm trying to communicate huge slabs of information in limited time. A talk with visual aids has a greater information bandwidth than one without.

Besides, redundant text on your slides is an important insurance policy, to make sure you don't forget to say something. If you've got time to practice your talk over and over then this isn't important, but if you write your slides two days before the talk and practice it once in your hotel room then they're helpful.

</comment></comment><comment><USER15> One of the major issues with slides is that too often they are designed to be usable without the presentation. Often times they are emailed to people who were not in attendance.

You end up in the worst of both worlds: a presentation where the presenter is nearly irrelevant (I can read slides too) and notes that are spread across too many slides to be useful.

It takes extra work, but developing one slide set for presentation and another set of materials (not necessarily slides) for reference works 1000x better.

<comment><USER16> An article or other write-up is a better "leave behind" alternative. You can include all of the points you made that were not on the slides and even a FAQ to substitute for audience questions.

</comment></comment><comment><USER17> I have noticed something, when I watch a movie with subtitles ( I am from Spain) even if it is in english, if I pay attention to the text I " disconnect" from the cinversation taking place. My attention gets focused in reading and I find difficult doing both at the same time. I don't see it as a good way to learn a language. I never thought about powerpoints though. It is an interesting idea....

</comment><comment><USER18> Excellent article. Its so true - these days people concentrate on increasing the slide numbers to make it appear as if there is a lot of content in it.No wonder, people hate most of the presentations these days.

'Words' and 'Expressions' along with a meaningful message are the best ways to communicate yourself across to a room full of people. Some visual material is as much important but only 'useful' material.

Rather than wasting your time on thinking 'how to fill N number of slides', it will be a lot more useful if we know our material, practice our material and choose our words carefully. Practice how to engage audience, than trying to make awesome visuals to enchant them with your slide making skills.

Why 'three slide' rule?

Lets make it a 'one' slide rule! :)

</comment><comment><USER19> I majored in a different field, but am now in the last part of an education in software design. At my present school, I have come to despise slides for anything but short presentations. In particular, the use of slides as the main ingredient in lectures is a disease. It is a general rule, rather than an exception at this place, that lectures consist of flipping through slides being almost verbatim copies of the material in the used text book at a rate of 0.75 slide/min on average during 90 minutes of lecture. Lectures add no value this way, but it seems like lecturers use "producing" slides as an alibi for having prepared a proper lecture.

</comment><comment><USER20> I have a similar rule, but my metric isn't slides but words: for a 20 minutes talk, I try keep the word count in my slide deck under 100 words.

More generally, I strongly believe that slides are only here as an illustration of what I say, they shouldn't be that useful without me talking in front of them.

As an example, here is a slide deck I used for a talk I gave at the MIT a few months back: <http://vimeo.com/24471964>

</comment><comment><USER21> I've become a big fan of Beyond Bullet-points.

I had a large client where I was doing a lot of Agile training. As part of that, I created a series of workshops around putting together a backlog when starting a project. There was no text -- it was simply pictures and me telling a story with them.

Two very interesting things happened. First, the students loved it. I'd talk/present for ten minutes or so, then we'd do stuff. Repeat and rinse. There was never a big wall of text for them to absorb, and I never read from anything. They were always _doing stuff_. And since it was stuff related to their specific project, even better.

The second thing was completely unexpected. The customer had a very mixed response to my material! It seems that they wanted something with a lot of text so that they could "teach" it themselves. A narrative, story-focused presentation that was integrated into the team's work was simply too difficult. They wanted a presentation that read like a textbook.

As far as being a good consultant goes, I'm not sure if I did a good thing or a bad thing in terms of the customer's long-term goals. But as far as the people I'm helping? I'm sticking to pictures and stories. Nobody wants to live through another Powerpoint hell, and I have no desire to put anybody through it again.

</comment><comment><USER22> A great read on the topic exists in book format, _The Cognitive Style of PowerPoint,_ by data visualization expert Edward Tufte.

Part of this book is freely available, discussing the involvement of PowerPoint in the Columbia disaster:

[http://www.edwardtufte.com/bboard/q-and-a-fetch- msg?msg_id=0...](http://www.edwardtufte.com/bboard/q-and-a-fetch- msg?msg_id=0001yB&topic_id=1)

The entire book is short, and only $7 from the author:

<http://www.edwardtufte.com/tufte/books_pp>

</comment><comment><USER23> 3 slides? too sharp... however, author expresses nice opinion - we tend to work way too much for technical stuff and waaaay too less for the actual content and message of the presentation

</comment><comment><USER24> If you employ a 3 slide rule what will happen is people will cram everything onto 3 slides.

The best presentation I ever did followed these steps:

1\. Type out everything you want to say. Learn it. It should be easy to learn because you should know your subject.

2\. Type out prompts as bullet points for each point your need to get across. Learn them, you should only refer to them if you absolutely need to.

3\. Use slides to illustrate your point. You should NEVER be reading directly from or using slides as prompts.

You are the presentation, not the slides.

</comment><comment><USER25> I agree in general with the sentiment but don't like rule of an absolute # of slides. To this day one of the best presentations I've ever seen had 500+ slides and is an example of what a good presentation looks/feels like.

<http://www.infoq.com/presentations/archaeopteryx-bowkett>

</comment><comment><USER26> I thought this was going to be an article about a new kind of slide rule. As in <http://en.wikipedia.org/wiki/Slide_rule>

</comment><comment><USER27> My no longer maintained list of the the impact of Powerpoint is at <http://sooper.org/misc/ppt/>

</comment><comment><USER6> I really liked the idea, "a presentation, being about content, not about slides". But enforcing 3 slides per presentation is ridiculous.

A presentation should be balanced between content and visuals. Content should be presented in a manner supported by visuals. You liked the graph because it was essential and supporting the information being transmitted to you.

Also, filling a presentation with unnecessary information and talk would turn the audience off and bore them.

So stopping and thinking before doing any writing down or creating any slides is good behaviour leading good presentations.

</comment><comment><USER4> I wonder whether all this would have been different if a ppt file (and similar) wasn't commonly called "a presentation" but e.g. "a deck".

</comment><comment><USER28> _Otherwise, it's like writing the introduction to a book before you've written the book._

Isn't that the standard operating procedure?

</comment><comment><USER29> The main advice is old: "Typing is no substitute for thinking."</comment>


Making a case for JavaScript, in-browser Mining - <AUTHOR> http://berk.es/2018/02/15/making-a-case-for-javascript-mining/ <comment><USER2> This idea is fundamentally flawed because mining is ultimately a zero-sum game. If this approach became commonplace as the author suggests, it would greatly increase the number of publishers squabbling over much smaller pieces of the pie.

In any case, you're effectively paying for the mining on your power bill. So nevermind that this approach disadvantages users who pay higher rates for electricity or have older, less-power-efficient computers.

<comment><USER3> the environmental and social impacts of mining at large scale have to be considered. it just does not seem wise to spend so much electricity and CO2 for mining.

<comment><AUTHOR> I did consider this, and spent an entire paragraph on it, in my article.

I agree, up to an extent, that mining as whole, has a problem to overcome. But, so far, there is no way to have a stake other than "electricity". And you need that stake (in the Proof Of Work) to solve the Byzantine Fault Tolerance.

Proof of stake, or even Proof of RAM (I'm just making that up here), Proof of Space are alternatives, some are actively being developed. Proof of Stake, might, potentially, solve this whole "energy wasting" thing.

But the fundamental question is: "Is it a waste of energy"? Is the burning of energy to secure a decentralized, autonomous, permissionless monetary system a "waste"? Maybe. but in that case there are far more obvious cases of "wasting" energy.

</comment></comment></comment><comment><USER4> When I pay in cash (digital or otherwise), I know what I give out in terms of value for goods or services. This concept of renting out your computer time on the other hand is vague. How much 'currency' will be mined? Will it be proportional to the goods/services I get to use in exchange? How long will the process take? What if my system fails midway during 'payment'? Can this concept be extended to run arbitrary code in your browser in exchange for the service? Right now Javascript is at least nominally related to the page you access. But what if tomorrow the code you're asked to execute is totally unconnected with the service being offered?

This just smacks of convenience for the implementers and as for the user, it exchanges a straightforward system for a murky deal.

<comment><USER5> Actually that's what I like about the idea. Reading prices, considering value of the things I buy in relation to those prices, picking most worthy alternative is a job that is assigned to every consumer by free market. I find it bothersome and after two decades or so of being consumer it is boring for me. Just saying "pay this guy whatever" without the fear of being taken to the cleaners sounds very attractive to me.

<comment><USER6> Hopefully it would encourage more interesting, long form content that keeps people on the page

</comment></comment></comment><comment><USER7> Opting in to in-browser mining is either stupid or theft. CPU mining costs more in electricity than you get out in currency. If you pay for your own electricity, you'd be better off donating directly. If you don't pay for your own electricity, you're donating electricity from whoever is paying for that electricity. This may or may not be theft, but is definitely morally dubious.

<comment><USER8> > If you pay for your own electricity, you'd be better off donating directly.

But to donate directly, you'd need a common payment service. That means registering (password and two-factor), then either transferring money to your account or authorizing it to draw from your bank account, and finally sending the payment, probably revealing a fair few bit of information about yourself to a website you may like but not necessarily trust. And every step of that process can be hacked, or have connection problems, or you may be on a different computer and need to re-login, and so on.

Paying with electricity lets you skip all that, and HN should be well aware that convenience is worth a lot of money.

In addition to that, with money you must choose how much to donate, and that is a burden on its own. (Does this blogger deserve one buck, or two? I gave two to that article last week, and this dude is almost as good, but I've decided my weekly budget is X €, and I'm almost over it, etc. etc.)

With a JS miner, you pay exactly as long as you keep the tab open, which is a pretty good proxy for how much the page is personally valuable to you.

<comment><USER9> > With a JS miner, you pay exactly as long as you keep the tab open, which is > a pretty good proxy for how much the page is personally valuable to you.

I don't think it is. People open links in new tabs for later, and "later" can be quite a while.

<comment><USER10> I mean its not like webpages know when tabs aren't active so they can suspend mining when you're not actively reading the content, right?

And its definitely not true that browsers can actively manage the resources available to inactive tabs, right?

Just because the current set of options doesn't respect these, that is not a reason to discard the idea entirely.

</comment></comment></comment></comment><comment><USER11> If browser mining was a good deal for the end user the vast majority of its proponents wouldn't feel the need for stealth. As it is implemented currently It's yet another example of preaditory behaviour killing herbivores at the digtal watering hole.

<comment><USER12> _If browser mining was a good deal for the end user the vast majority of its proponents wouldn 't feel the need for stealth._

Paul Graham might disagree;

"The two most important things to understand about startup investing, as a business, are (1) that effectively all the returns are concentrated in a few big winners, and (2) that _the best ideas look initially like bad ideas._ " (emphasis mine) [From [http://www.paulgraham.com/swan.html](http://www.paulgraham.com/swan.html)]

Stealth is not necessarily a sign something is bad; it might just be hard to persuade people that it's good, and that's a reason to be stealthy.

<comment><USER13> I'm afraid the doctrine of "if it looks bad, it must be good!" is not in fact true or generally applicable. And it's not what Graham is saying, for that matter. If you read a bit further:

"It also reminds you that the vast majority of ideas that seem bad are bad."

The idea of running up every web browsing computer to 100% CPU, costing them tens of dollars in electricity while giving you a few cents of cryptocurrency, seems bad and is bad.

</comment></comment></comment><comment><USER14> Please no, the carbon footprint is just too high:

[https://www.wired.com/story/bitcoin-mining-guzzles- energyand...](https://www.wired.com/story/bitcoin-mining-guzzles-energyand- its-carbon-footprint-just-keeps-growing/)

<comment><USER15> Compared to heating and cooling, and a bunch of other stuff it is negligible.

I guess you could complain about the usefulness of mining.

Well, people do a bunch of useless stuff that has magnitudes bigger carbon footprint than mining.

Let's not optimize things that are insignificant.

<comment><USER16> It's not insignificant. Bitcoin mining already consumes as much energy annually as Denmark – that means the entire country, heating, cooling, industry, everything:

[https://arstechnica.com/tech-policy/2017/12/bitcoins- insane-...](https://arstechnica.com/tech-policy/2017/12/bitcoins-insane- energy-consumption-explained/)

<comment><USER17> I don't have a good intuition for that kind of heterogeneous comparison.

Can it be compared with other Internet services? How much electricity does Facebook consume, for example? What about internet advertisements?

<comment><USER18> It's 5 times what USA use on christmas lights: [https://phys.org/news/2015-12-christmas-energy-entire- countr...](https://phys.org/news/2015-12-christmas-energy-entire- countries.html)

Or 3,5 times what Amazon US-East cluster consumes: [https://datacenterfrontier.com/amazon- approaches-1-gigawatt-...](https://datacenterfrontier.com/amazon- approaches-1-gigawatt-of-cloud-capacity-in-virginia/)

</comment></comment></comment></comment></comment><comment> trey-jones I wrote a tool to enable this, and promote responsible use:

[https://github.com/trey-jones/xmrwasp#a-word-about- responsib...](https://github.com/trey-jones/xmrwasp#a-word-about- responsibility)

So I guess I'm clearly in favor of it. In general I would prefer opt-in mining to advertising. If you are interested in why, I'll be happy to discuss. I think my thoughts are laid out in the README.

I also made a simple demo page here:

[https://www.xmrwasp.com](https://www.xmrwasp.com)

It won't mine unless you ask it to. The point of the demo is to check out what impact various degrees of mining have on your other activities. The default is VERY low with a single thread and 50% throttle.

I'm not sure if this is a polarizing topic, or if I'm not thinking clearly about it because I've gotten on the boat, drunk the kool-aid, or whatever.

</comment><comment><USER19> When we look at conventional money, (specifically the USD,) "printing" money is available to almost everyone with decent credit. We print money when we use credit cards and when we take out a mortgage on a home.

If websites took small payments in a cryptocurrency where mining the cryptocurrency took about the same amount of time as it takes to consume the content, then "printing" money is available to almost anyone with a decent device. It's also a good way to set a price for content; instead of some bozo thinking that his/her article is worth $3 or $15.

I think that cryptocurrency, as a technology, still has far to go before it can support this kind of commerce. This is in terms of technological improvement, scalability, and a design that takes into account how economics works on a large scale.

</comment><comment><USER10> HN of all places really surprised me with this reaction. Publishers _desperately_ need an alternative payment system with the convenience of an ad-supported model, microtransactions, and a direct payer-payee relationship. Browser-based mining has a potential to provide that, but it is still very early and evolving.

Also why is everyone talking about Bitcoin in this thread? No one is trying to mine Bitcoin in the browser. There are other cryptocurrencies than Bitcoin. Some of those are designed to run in the browser specifically to address the concern with using a POW system in an intentionally resource-constrained environment.

</comment><comment><USER20> > Quite some cryptocurrencies use a mining algorithm for which making > specialised hardware is impossible

There is a GPU miner for Monero (actually, there is a GPU miner for everything) which turns in-browser mining into not that profitable idea.

<comment> trey-jones Cryptonight is specifically designed to be more friendly to CPU mining. You can read more about that in the Monero team's recent blog post:

[https://getmonero.org/2018/02/11/PoW-change-and-key- reuse.ht...](https://getmonero.org/2018/02/11/PoW-change-and-key-reuse.html)

It seems they have opted to prefer browser miners and botnets over centralization caused by dedicated hardware (ASICs).

Profitibility in the traditional sense factors in electricity, but when you're using someone else's electricity, that's not a consideration. If you have enough users, the return is quite reasonable for the site owner.

</comment></comment><comment><USER21> What is groundbreaking about Brave?

<comment><USER22> Whenever an advertisement is displayed to you, brave awards you BAT which you then pay a percentage of to the site owner.

Brave also controls what kind of advertisements you can see and prevents things like auto playing videos and full screen ads from cropping up.

It also allows you to apportion micro payments to content producers.

Won't weigh in on whether this makes brave groundbreaking or not, but this is at least part of what it does that makes it unique.

It also has this whole interface it exposes to advertisers and content owners I don't fully understand.

</comment></comment><comment><USER23> Is this for real? There is no justification. It's theft plain and simple. Nothing has gotten me to turn on NoScript by default but if this becomes commonplace I will.

I know the author is doing opt-in mining but that's obviously going to be as popular as opt-in ad tracking vs automatic. The model will be pages just serve up the in browser mining without asking.

<comment><AUTHOR> > It's theft plain and simple

I explicitly made a case for opt-in. How is that "theft"?

And whether or not that is popular is besides the case. If it is impopular, it still is not "theft", is it?

</comment></comment><comment><USER24> [https://medium.com/@fubukilabs/ethical-use-of-browser- based-...](https://medium.com/@fubukilabs/ethical-use-of-browser-based- cryptocurrency-mining-4c6c82c1a7f6)

</comment><comment><USER25> I think the best use case is would be for non-profit that depend on donations like Wikipedia or perhaps video streaming websites like Youtube(consumed using Desktop).

<comment><USER26> Maybe youtube could secretly encode keyframes in your browser.

</comment></comment><comment><USER27> The fonts and images on the blog are really stylish. Props for the design!

<comment><AUTHOR> Thanks! If you're interested, the blog is in Jekyll, and all of it is open source ad on github: [https://github.com/berkes/berkes.github.com/](https://github.com/berkes/berkes.github.com/)</comment></comment>


Some Notes on Haskell Pedagogy - <AUTHOR> https://medium.com/@sjsyrek/some-notes-on-haskell-pedagogy-de43281b1a5c <comment><USER2> Some good thoughts in here. However I feel like when I learned Haskell (which was actually my first serious foray into programming) the hard parts were not this high level functional language philosophy stuff, but rather not knowing how to appropriately use the tooling. It took me years to finally write cabal files, QuickCheck tests, Traversable instances, etc. In that regard, this guide has been immensely useful:

[http://dev.stephendiehl.com/hask/](http://dev.stephendiehl.com/hask/)

<comment><USER3> I've had very similar experiences. I took a Scala course on Coursera back in 2014 and at the end I realized I couldn't really write a Scala program because the course had provided all SBT files for everything...and because they enabled all sorts of functionality related to autograding, they were impenetrably complex in addition to the necessary complexity of a build tool (which requires a willingness to read a technical manual that assumes I high level of experience and sophistication).

A lot of the difficulty is that it is relatively easy for a two pizza team to have enough experience and knowledge to collectively figure out how to get all the moving parts moving more or less in the right direction at more or less the right time. For an individual, it's always going to take years to achieve the equivalent knowledge of a team after six months.

</comment></comment><comment><USER4> functor, sum type, recursively defined.

This teaching opportunity is already lost. Who are you teaching to? Someone new to programming is going to be lost by the first example.

<comment><USER5> I agree. From the article:

> The | operator indicates that this is a sum type [..]

This doesn't explain what's going on; it references terminology used only by people who already know what's going on.

A pedagogical explanation would say: the | operator means "or", in that you can use multiple different constructors (separated by |) to construct the type in question (whose name is to the left of the '=' operator). For example:

        data Bool = True | False

means that you can construct a value of type _Bool_ using one of the constructors _True_ or _False_.

<comment><USER6> But the constructor approach does not explain what makes a sum type a sum.

If the readers already have some background in a programming language, you could also start with e.g. a struct from an imperative language:

      struct Foo {
        X x;
        Y y;
      }

This is a so-called product type, because the number of possible values of _Foo_ is the number of values of type X _times_ the number of values of type _Y_. So if _X = {Red, Green, Blue}_ and Y = _{Light, Dark}_ , then this product type has _3 x 2 = 6_ different values:

      Foo {Red, Light}
      Foo {Green, Light}
      Foo {Blue, Light}
      Foo {Red, Dark}
      Foo {Green, Dark}
      Foo {Blue, Dark}

What if instead, we wanted to have the sum of the possible values of X and Y? In other words, where we'd have to choose between a value from X or from Y?

      Foo {Red}
      Foo {Green}
      Foo {Blue}
      Foo {Light}
      Foo {Dark}

That's a sum type: it is a type where you can pick a value from X _or_ Y, giving a total of _3 + 2 = 5_ possible values.

Then give a motivating example where one would need such a type (e.g. trees nodes) and introduce proper notation.

<comment><USER7> I agree with your approach, one suggestion: If you're using struct to introduce product, does it make sense to use union to explain sum? Although maybe that's too complicated given the need to tag it?

</comment></comment></comment></comment><comment><USER8> "Pedagogy" is the art/science to guide kids, literally speaking. First, I wasn't sure if he didn't actually mean "didactics" but then he talked about "students" so he probably just talks about "kids" of computer science.

Why are all thoughts about how to teach/promote Haskell centered on the language itself as if it were only an academic tool? If you want students to get excited about Haskell, don't make it look like an academic tool that's only useful as a didactic device in university classes on functional programming.

<comment><USER9> > "Pedagogy" is the art/science to guide kids, literally speaking. First, I > wasn't sure if he didn't actually mean "didactics" but then he talked about > "students" so he probably just talks about "kids" of computer science.

 _Literally_ speaking, you may be right, but who cares? "Pedagogy" means "teaching" to anyone who is seriously engaged with the topic of conversation here. Etymology is not meaning. Defining words by their etymology alone ignores history, culture, and the context of modern word use.

<comment><USER8> It matters when you're teaching professionally.</comment></comment></comment>


The Startling Link Between Sugar and Alzheimer's - <AUTHOR> https://www.theatlantic.com/amp/article/551528/?single_page=true <comment><USER2> Title should be "The startling potential link between elevated sugar and Alzheimer's"

<comment><USER3> A potential link is a link.

And elevated sugar indicates excess sugar, and excess sugar is a form of sugar.

So the headline is fine. You're projecting things onto it which weren't said and then complaining those things aren't clarified in the title. That's what the article is for.</comment></comment>


Why Google+ will succeed wildly. At first. - <AUTHOR> http://goodexperience.com/2011/07/why-google-will-succe.php <comment><USER2> Just because you can't do it now, doesn't mean you won't use it if you could.

"If you look at how people use their horses, the majority of them don't go over 15mph."

We'll see what happens with G+ vs. Facebook. I suspect there will be feature list battle coming up. Aside from patents, there isn't much stopping Facebook and Google from stealing each other's improvements.

</comment><comment><USER3> Right on the money. Filtering who reads your messages isn't a pain point, nor does it appeal to our psychological senses. It's just a technical feature... a feature that only a software engineer would obsess about, and turn into a full-fledged product. Sorta like "Color".

<comment><USER4> Filtering IS a pain point if you have very different audiences amongst your facebook 'friends', like real friends vs co-workers vs parents. Not having filtering may prevent you from making a personal post that would be funny to your friends but crude to others. The author asks how many people want fewer readers of their posts, but for non-technical users, number of readers isn't a concern at all. Publishing something embarrassing then remembering your grandmother is now a friend, on the other hand, is an annoying concern.

There's still a question, though, of whether people will think it's worth the effort to categorize all their contacts. I'm not sure how many will bother.

<comment><USER5> If Google+ said "here's your list of several hundred contacts, now categorize them" I would never get around to it.

But what they mainly present me with is three contacts at a time, always visible, and it just takes a couple clicks to categorize one. Then I get to see who pops up next. Every time I go on g+ I do a few of them without really thinking about it. And if you saw my hard disk you'd see I'm not much for organizing at all, generally.</comment></comment></comment>


Friendster Founder Raises $1.7M To Start Hiring At Social News Reader Nuzzel - <AUTHOR> http://techcrunch.com/2012/11/08/nuzzel-funding/ <comment><AUTHOR> If any HackerNews member wants a Nuzzel beta invite, email firstname.lastname@example.com and put HackerNews in the subject of the email.

<comment><USER2> Just sent an email, Jonathan. Thanks in advance!

</comment></comment><comment><USER3> Here's an hour long interview with the founder, Jonathan Abrams, on This Week in Startups with Jason Calacanis from just a couple of days ago: <http://www.youtube.com/watch?v=GDs2nJf6lro>

Good interview, and Nuzzel is an interesting idea. I'm not entirely sure it's something I need, but I'll give it a shot. There's certainly room for an awesome product in the space.

</comment><comment><USER4> Good for him. Friendster was awesome and way ahead of the curve.

</comment><comment><USER5> congrats Jonathan!</comment>


Why Complexity is Different - <AUTHOR> https://mystudentvoices.com/why-complexity-is-different-ecd498e0eccb <comment><USER2> Wow that was a great article! Really helped me understand a lot of concepts I was only vaguely familiar with before, thanks.

</comment><comment><USER3> I admit I was a little surprised that I got to the end and hadn't seen any 'And the reason this is relevant to software is that for your software to be understandable, grokkable, analysable, etc. you need to think about how the details affect the whole' section.

Excellent article nonetheless.

<comment><USER4> I come up with one for you:

The clear separation of microstates and macrostates in software, through proper abstractions is a key to good software quality.

Unfortunately the lack of abstractions or the prevalence of leaky abstractions, due to bad design and software management practices (e.g. monkey patching) eventually leads many codebases into its critical point. In this critical state small perturbations of microstates (either at development or at runtime) causes unpredictable behavior changes at macroscale level.

So if you ever have wondered why our software quality is worse than the laws of thermodynamics would justify:

Our best physicists are now working on theories based on renormalization groups to exactly describe the expected distribution of blue screens of deaths: To have much better models of how bad our applications are! ;)

</comment></comment><comment><USER5> This gives a great perspective on complexity. Reminds me a lot of the book An Introduction to General Systems Thinking by Jerry Weinberg. [https://www.amazon.com/Introduction-General-Systems- Thinking...](https://www.amazon.com/Introduction-General-Systems-Thinking- Anniversary/dp/0932633498)

</comment><comment><USER6> more "Complex Systems" links ( Philosophy of Science )

[http://philsci-archive.pitt.edu/view/subjects/chaos- theory.h...](http://philsci-archive.pitt.edu/view/subjects/chaos-theory.html)</comment>