Ask HN: What did you learn last week?

I learnt that api gateway templates don't have a good stringify function. You can turn a string into json and do stuff with it, but you can't write it back without having your own function for it

martin_a• 4 years ago

The special software we're using for automation in the print industry switched to TypeScript with the last major release.

I finally found the time to get into that and wrote my first two scripts with TypeScript and the overall new system to do scripting.

Still struggling with the finer bits, but access to npm et al. really helps with getting done what needs to be done without reinventing the wheel.

okhuman2• 4 years ago

Last week felt like I finally understand how webauthn and passkeys work - now my auth server has a "passwordless" login flow https://github.com/authcompanion/authcompanion2

dmkirwan3• 4 years ago

Was there anything in particular that made this click for you? If you have any resources to share I'd love to see them.

aaaaaaaaata• 4 years ago

Guide to Web Authentication - https://webauthn.guide/

okhuman2• 4 years ago

I started on the abstraction level with SimpleWebAuthn and implemented a POC to get a sense of the general flow: https://simplewebauthn.dev/docs/simplewebauthn/philosophy

Then referenced how to FIDO for more information: https://github.com/fido-alliance/how-to-fido/blob/master/How...

hope that helps

smcn• 4 years ago

I've been trying to learn how to properly use Twitter to market my startup, and I found out that hashtags are better than cashtags when tweeting about stocks. That is, #AAPL is better than $AAPL.

This is the reverse of what I had expected because there seems to be vastly more people using cashtags but my theory is that 1) people still search for hashtags and 2) more volume means your tweet is visible for less time.

However, the best is obviously mixing them. I have a thread during premarket trading hours where I discuss stocks that the algorithm has decided is interesting and I'll print out the current score using hashtags, but use cashtags for quick discussion on stocks.

Example here: https://twitter.com/0xsmcn/status/1568155410191851521

nope96• 4 years ago

I learned that Stable Diffusion can read! It's called a "typographic attack". https://www.theguardian.com/technology/2021/mar/08/typograph...

For example, this site lets you create variations on an image that you upload: https://47725.gradio.app/

Feed it an image of text (type text in a paint program and save as PNG), and it seems to understand some words. https://i.imgur.com/aXELmHo.png

fragmede• 4 years ago

For posterity, since it will die ~soon; that gradio app is a live version of this repo: https://github.com/justinpinkney/stable-diffusion

dmkirwan3• 4 years ago

I've been learning a lot, fast, by trying to build out the same (very simple) full-stack web application in using different frameworks. Different backends, different frontends and different databases. Admittedly, I've been doing this for slightly more than one week. It's been a lot of fun, I must admit. It's interesting to see the different quality levels in documentation, availability of help on StackOverflow, and tooling.

I'm not approaching it with any real goal other than to see how some other frameworks work but it feels very worthwhile.

woleium2• 4 years ago

Interesting, which has had the best docs so far? I often feel that the docs make the language, and it's not a thing that many folks talk about.

dmkirwan3• 4 years ago

The rails docs are excellent, actually! I was surprised at how bad the node.js docs were, but the documentation for express.js is good enough that I didn't find myself referencing the node docs a whole lot.

C# and .NET have been pretty easy to develop in, but the documentation was very poor I thought. Maybe I just didn't find it, but it lacked a good example walkthrough like you get with Rails. Next up is a Swift backend using Perfect[0]!

[0] https://github.com/PerfectlySoft/PerfectDocs

dhsysusbsjsi• 4 years ago

I learned that in SwiftUI if you don’t want a view to re-render when one of its properties changes, but you need it to have that property/state because it needs passing to children, you can just make it a regular variable without the @PropertyWrapper.

Seems pretty obvious in hindsight!!

marak8303• 4 years ago

If I had a dollar for every time something seemed obvious in retrospect....

marak8303• 4 years ago

Became alot more knowledgeable about using Jira and our clients expectations

Bookmarklets haha I didn't even know they existed(was always using tampermonkey and such), in addition adjusting html on the fly for our logging system

*13 days is a long week, next time you put your hand up for OT, specify that you meant either day, not both xD

thebeastie• 4 years ago

More webgl / three.js. There seems to be a lot to learn. Starting to look into shaders. It’s hard because my math sucks and alot of it is maths, albeit basic matrix calculations and geometry.

hereyougo2• 4 years ago

From a comment here yesterday I learned the [2n] [2n+1] array layout for a binary tree is also known as the "Etyzinger" layout.

https://algorithmica.org/en/eytzinger#the-eytzinger-layout

hifikuno• 4 years ago

I learnt to double check that an image will actually work on my device. Tried flashing a newer version of DD-WRT to a router I was using as a wireless bridge. That device is now an ugly paperweight and I have two computers without internet.

orsenthil• 4 years ago

I created 3 projects with Javascript. Maintained my C language project. Learn about infrastructure, aws and kubernetes. Continued my fintech and stock trading learning. Experienced an entrepreneur challenge with focus that is required to continue evolving a project, while facing people challenges.

Discussed with friends regarding economics.

joshmn3• 4 years ago

I learned that my dad isn't my father. He didn't even know he wasn't my father. My mom passed away a few years ago and took this secret to the grave with her.

I took an Ancestry.com DNA to try to answer the question of: "what, in my ancestry, if anything, results in me not being able to tan well at all?" (compared to my mother/father). In doing so, I was also greeted with another surprise: my mother happened to do one of these tests herself! She showed up on my list of matches. This made it really easy to determine who all was on her side via the "shared matches" feature — you can see a list of names/usernames of people who have opted in to this feature and share some DNA with you.

This meant that it was very easy to distinguish who was on my (biological) fathers side.

I'm cool with it, though it's an itch I'm insatiably trying to scratch. Oddly enough, someone who I share a considerable amount of DNA with has an uncle who worked in the same town as my mother did the year I was conceived — otherwise, the entire family has no relation to the region my mom hung around in that year (or any prior year). However, for all my fruitful digging (and I'm usually very good at the finding-people-on-internet part), I cannot turn up any solid email address or phone number for the guy. Coincidentally, I can see his old law office from my patio, and he lives a few blocks away from my partner.

World is weird.

Cyberdog• 4 years ago

My father always knew his "father" was not his biological father, but it wasn't until a couple years ago (when he was in his mid-60s) that he was able to find and connect with the half-brothers and -sisters he never knew he had, from the family his bio-father made after he left my father's mother and never looked back.

At any rate, how did your father take the news?

joshmn3• 4 years ago

The situation you describe is the one I'm curious to avoid.

My old man was sort of "bah humbug" about it all. He wasn't necessarily "surprised" that my mom would do such a thing, but still "surprised" — eyes wide open, shaking-of-the-head.

My mom was notoriously sneaky, though her legend is prototypically more tame than this: "oh look at this cat I found on the sidewalk that was lost!", or "this dog was going to be put down if someone didn't take it."

My favorite story though is that when they (my mom/dad) went on a week-long canoe trip: your pack is usually heavy when you start and is supposed to get lighter as you go — you know, from the food you eat. Well, my dad noticed his was not getting any lighter as the trip went on. Fast-forward a few weeks, my mom is out working in the yard and my dad goes out to get something when he notices some really particular rocks that match at all with the existing rocks that were laid.

Little did he know he carried in his pack during their canoe trip.

The rest of the day (I broke the news to him shortly after lunch hour) we spent the day chuckling about "how 'Jeanine' it is [of a situation]" — Jeanine being my mother. We found common ground there if nothing else.

bwb2• 4 years ago

Pumkin pie is not made of pumpkin, rather butter nut squash… why???

silisili• 4 years ago

This isn't strictly true...you can use either. Libby's for example is 100% pumpkin.

I think a lot of people use butternut squash because it's sweeter, more available, and has a nice texture.

bwb2• 4 years ago

https://greatist.com/eat/canned-pumpkin-puree-is-actually-sq....

oschvr• 4 years ago

I learnt how to backup data from Prometheus stored in a Persistent Volume in Kubernetes. many ways of doing this but the one I found backs up a tar to a bucket, which is pretty convenient.

dpkirchner2• 4 years ago

I learned that my favorite pizza place, that I've been disappointed with lately, is getting a lot of 1 star ratings from folks these days. Guess I'm not the only one disappointed.

It's a huge bummer. It took a while to find a good option!

mod2• 4 years ago

What changed that is leaving you dissatisfied?

Do you know why it's happening?

dpkirchner2• 4 years ago

They stopped selling some of their "specialty" pizzas and removed their component ingredients from their menu. Worse, but rarely, the pizza would arrive a little bit doughy, like it wasn't fully cooked.

For the former, I don't know why it was happening -- guess I could ask -- but I suspect they're having trouble sourcing those ingredients at acceptable prices. For the latter... we'll, that's just laziness and inattention.

cgreerrun• 4 years ago

Stereo Reconstruction

It's the algorithm(s) for how to compute a depth map when you have images from two cameras spaced some distance apart (for e.g., our eyes). It's gotten really good recently and it's fascinating on a technical level. Check out this YT video/playlist if interested: https://www.youtube.com/watch?v=6hr6xpOU-uw

Also, great question! Should do it every week.

SecurityMinded• 4 years ago

I learned not to trust any home services contractors' word. Have been left out to dry by 3 of them in one week after confirming appointments a day or two before.

On the flipside, I learned how not to paint walls, i.e. learned doing it the wrong way.

I learned a sump-pump advertised to pump 500 gal water per hour will take 3-4 days to pump the muck out of my swimming pool in 4-5 days, i,.e. not to trust those ratings.

thehoff• 4 years ago

I’ve had this in the past year as well. I don’t get it. They may be really busy but it seems like bad customer service on their end.

The ones that either don’t return calls or emails or just don’t show, I’m never reaching out to them in the future and I’m never recommending them. But maybe it will never matter?

mod2• 4 years ago

Maybe it's an epidemic, I've been through a ton of repair guys lately. At my business we have a lot of HVAC work (AC, coolers, ice machine), plumbing work, and occasional other stuff like locksmiths or handymen.

They just absolutely will not show up when they say they will. Late, sometimes no-show. I had a plumber take FOUR visits over FIVE days and still not solve the (relatively minor) issue.

I don't know if there's just that much work out there? I think anyone who shows up could make a killing in my area, for any kind of repair work. I've never shopped around on price, either.

satisfice• 4 years ago

Last week I learned that Sextus Empiricus argued that learning is impossible.

altilunium• 4 years ago

Dig dive into OpenStreetMap ecosystem by reading weeklyOSM archives.

[1] https://weeklyosm.eu

givemeethekeys• 4 years ago

I finally understood the difference between references and pointers and now the reason for Box pointers in Rust makes more sense.

rad_gruchalski• 4 years ago

Went through The Art of Prolog and Prolog starts clicking on.

ozzythecat• 4 years ago

I learned that I put my faith and trust in some people who were never sincere and were simply using me.

Sometimes you flock to someone because you see them being kind, considerate, and overall a strong leader.

It turns out that some people know how to fake these qualities. They’ll use you, and while you look up to them, they see you as a pawn in a chess game.

Assuming that people make mistakes and everyone actually just means “well” or has good intentions, it’s extremely naive. People will sell you that shit and take advantage of you.

I got gaslighted enough times and finally saw what was happening.

drukenemo• 4 years ago

I got curious to know more about your story. How were you used and what made you realize what was happening?

gr1zzlybe4r• 4 years ago

I learned that it's ok to be working a job or on something just because it can be stable and it pays the bills. I think I've looked to work maybe too much for purpose, and if you're not working for yourself it's going to be very hard to find fulfillment when doing that.

So basically learned to be ok with not seeing work as a purpose driver for me at the moment.

BOOSTERHIDROGEN• 4 years ago

Grafana and InfluxDB

tsol• 4 years ago

Turns out it's pretty easy to do a multiple long day fast if you spend a few weeks cutting out carbs first

roydivision• 4 years ago

I learned that S3 buckets don’t have a concept of directories, even though a lot of clients make it look like they do. It is possible and valid to store an object such as

/foo/bar

Without /foo existing.

This can cause problems in certain circumstances. Beware.

Triangle9349• 4 years ago

I saw a man with a device similar to a gameboy, it was a M8 Tracker. He showed a little and talked about music trackers. As a person far from music production, my mind was blown away. All week I searched on youtube everything about: Music Trackers(M8, Renoise, Milky Tracker, SunVox), Ableton, VSTs, Pure Data, Touch Designer, Synthesizers, etc I don't know what to do with this information, but it seems I will have a new hobby.

RonaldOlzheim• 4 years ago

Sometimes you know that uou are not the problem, but your response is a habbit and the habbit is the reason that you experience the feeling of having a problem.

The union

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