The Stack Overflow Podcast

How to build a universal computation machine with Tetris

Episode Summary

The home team talks about how engineering blogs create real value for software companies, a game-changing accessibility controller for PS5, and how to build a universal computation machine using Tetris. Plus: Is this podcast responsible for Instagram’s decision to boot the shopping tab from the home feed? Maybe!

Episode Notes

First, some self-administered back-patting for the Stack Overflow editorial team: great engineering blogs give tech companies an edge (The New York Times says so). 

Hiring aside, engineering blogs are fresh sources of knowledge, insight, and entertainment for anyone working in tech. You can learn a lot from, for instance, blog posts that break down an outage or security incident and detail how engineers got things up and running again. One classic of the genre: Amazon’s explanation of how one engineer brought the internet to its knees. And here’s an example from our own blog

When you’ve finished catching up on the Stack Overflow blog, check out those from Netflix and Uber.

Good news for late-night impulse shoppers: Instagram is removing the shopping tag from the home feed, reports The Verge. Is this a response to widespread user pushback, and does this herald the end of New Instagram? We can hope.

Sony announces Project Leonardo, an accessibility controller kit for PS5.

Did you know? Using only Tetris, you can build a machine capable of universal computation.

Developer advocate Matt Kiernander is moving on to his next adventure. If you’re looking for a developer advocate or engineer, connect with him on LinkedIn or email him.

One of Matt’s favorite conversations on the podcast was 

our episode with Mitchell Hashimoto

, cofounder and CEO of HashiCorp. It’s worth a (re)listen.

Episode Transcription

This episode is brought to you by Backtrace! Complex software design can sometimes cause catastrophic errors. Backtrace I/O provides tools that make sure your development process moves forward, even in the face of these challenges. Visit us at and sign up today!

[intro music plays]

Ben Popper Hello, everybody. Welcome back to the Stack Overflow Podcast, a place to talk all things software and technology. We are in a new year. I have been drinking non-alcoholic beer. It's Dry January. I'm getting through it and we're a third of the way through. And I am joined today as I often am by wonderful collaborators, Matt Kiernander and Ceora Ford. Hi, y'all. 

Ceora Ford Hi! 

Matt Kiernander Hello!

BP So I don't want to toot my own horn, but to start the episode I have to say there was a piece in The New York Times, the paper of record, that said engineering blogs are very important if your company wants to hire engineers, great for that. But just so everybody knows, the Stack Overflow Blog is a great place to come if you want to write about technology. Lots of companies come and work with us to do sponsored blog posts where their engineers write great things, and it was fun to read this in a sort of general interest news publication and have the thesis kind of affirmed, which is that what engineers love is to read about real processes, real problems, tools people use, and how they built things to get down, as some of the engineers said, in the trenches with other people who are working. So thank you for that chance to promote myself and pat myself on the back. But in the same vein, if you ever want to write for us or come on the podcast or whatever, please do reach out because that's what we're here to do, to create content by developers for developers. Okay, I'll stop talking now.

MK I think the Uber engineering blog is actually a really good resource, because I remember reading something a couple years ago now where they were talking about the evolution of the Uber app and how they had to do some really crazy optimizations to get the bundle size down because it was growing more and more, and then with Apple and the App Store, they had certain restrictions that they needed to be under a certain size and so they had to do some absolutely mind-blowing things to try and bring everything down and get to the point where it was actually possible to ship to the App Store. I enjoy –Ceora, I'm sure you must be of a similar mindset– seeing these kind of transparent, kind of post mortems of real problems that they had. 

CF Yeah. I really like Netflix. They used to be very heavy with their developer blog on Medium. I'm not sure if they're still there, but they have a developer blog and then they also have developer-centric videos and talks on YouTube. And I remember this because I remember reading and watching a lot of the stuff they put out about GraphQL at my last job, because they're one of the companies that is a big proponent of GraphQL, and they talked about why they use it and how they use it and how it helps them and all that kind of good stuff. So I think a lot of times individual bloggers or engineers will publish things about their personal projects or their personal learnings, but sometimes when you hear it from the perspective of a team at the enterprise level it gives you different insights that I think are very valuable. 

BP Totally. I like it because it pulls back the curtain a bit, like you said. And often, it's less opinionated, like, “Here's how we did this,” or, “Here's why we did this.” It's like, “Somebody told us we had to do this and we didn't know how to do it and so we tried to work through it and figure it out,” and that I think is always appealing. There was a writer, Gergely, who did a little writing for us and now he's got his own little media empire. He’s got a popular Substack, he's always breaking news on Twitter. He used to be an Uber engineer and he wrote for their blog, so he's taken it out full-time now.

CF Very cool. 

MK I actually also really enjoyed reading about when companies have disasters like, “Our whole tech stack burnt down and this is how we got it back up within three days.” I find that kind of stuff really interesting as well. I think Amazon had one a couple of years ago where one of their either interns or junior engineers accidentally took down Amazon for a small period of time, and instead of being like, “This is your fault,” it was like, “This should not have happened. It was not the fault of the individual. It was a system failure, and this is what we're going to do to prevent it.” It was kind of one of those things where I'm not even mad, I'm actually quite impressed. A junior engineer should not be able to bring down Amazon, but it happened and then they had a whole thing describing how they were going to fix that potential issue moving forward. 

BP Got to love the blameless accountability. That's good. All right, next link. I have to confess there were a bunch of really cruddy toys that got purchased over this holiday season on a 3:00 AM Instagram TikTok jag, where it pops up and you just hit ‘buy’. Somebody dropped a link here, “Instagram removes the shopping tab from the main app.” Ceora, I know in the past you've told me this is your one guilty pleasure. Why'd they take it out? Why'd they take it out? What did they say? 

CF I added this link because I think maybe a couple months ago we had talked about Instagram's UI and how they're being very video-focused and e-commerce focused now. And I think that they're slowly but surely trying to return back to their roots. That's what I'm interpreting this as. Because they've removed the shopping tab, and you still can shop on Instagram but it's just not one of their primary functions in the home feed. And they also moved the Reels tab so that now the button that your thumb most naturally falls on is the button you press to make a new post instead of the button for viewing Reels. 

BP Somewhere a UX designer just had a galaxy brain explosion when you said, “The place where your thumb most naturally falls.” That's what they want to hear, that they've got that button right in the sweet spot. 

CF I'm going to imagine that they listened to our podcast and they were like, “You know what? Let’s change and go back to our roots.” I'm happy about it because I'm interpreting this as them eventually, a couple months from now, The Verge will be like, “Instagram is now changing their algorithm to start promoting photos again,” and stuff like that. That's the goal. 

MK Good luck.

BP Running in reverse chronology here. Yeah, exactly. It’s going backwards in time. 

MK So if I'm understanding this right, they’re getting rid of the shop tab and replacing that with the Reels tab within the main UI?

CF Yes. But you can still shop on Instagram. That function is not being taken away, but it's not in that home menu there on the bottom of the screen. So yeah, they changed it a little bit. 

MK I'm wondering if the way that they kind of evaluated this decision was that they were making X many dollars with the shop store and the potential future X many dollars with Reels, and then they're just kind of juggling things to make sure that Reels is getting the attention it deserves.

CF Well, the thing is, they moved the Reels button too. They have a little picture of a sample of what the UI for the Instagram homepage is going to look like now that they've made this change. Initially the Reels button was right in the middle, so that's the main button that they want everybody to press. They changed that. The Reels button is moved where the shopping tab is, and instead of the Reels button being there, it is the button you press to make a new post. I am curious to hear what motivated them to make this change, but I know a few months ago everybody was like, “Oh my gosh. No, we don't want Instagram to be like TikTok. We want pictures and things like that.” So I'm hoping that this is one of those instances where a company hears people's feedback and they're like, “You know what? Let's follow it because this is what the people want.” I'm hoping that's the case because honestly, that's kind of what I wanted. So it's a good change in my opinion. 

BP Good. They're listening to you. Sony announces a new accessibility controller for the PS5. I saw this and some other cool stuff come out of CES. Who dropped this in and why is this so cool? I mean, it sounds cool, but what's especially interesting about it? 

CF Yeah, I dropped this in. It's really interesting because this is a culmination of Sony trying to make a lot of their products more accessible, especially as far as video games go. I'm not a gamer so I don't really know anything about this, but I was reading and the PlayStation 5, what they've been trying to do, is create a controller that is more suited for people with accessibility needs. So they have announced what they're calling Project Leonardo, and it's a controller that has a bunch of different configurations and settings so that you can hook it up to accessibility devices. You can also connect the buttons to different actions that would be on the PS5 controller– the regular one. 

BP Oh, I see. So like, “This button is an up-left joystick push.” 

CF Right, exactly. So it's super customizable and they consulted with accessibility experts on people with disabilities to make sure that this would be as helpful and useful to them as possible. I just thought that was really cool, and I've also learned that they have a program. They launched a program in 2021 where developers can submit their games to Microsoft to have them evaluated for accessibility, and they get tested by gamers with disabilities. So I thought that was really cool. I'm not a gamer. The most I have is a Switch, but I do think it's really cool that they're trying to make sure that everyone can play and enjoy games, and even make sure the games themselves are accessible to everyone. 

BP I like the concept here which is that it's all modular. It's this huge wheel and you can build it out to suit whatever your particular needs may be. 

CF Different parts you can take apart and put it here and then all that kind of stuff. 

BP You say you're not a gamer. The gamer brain, I'm like, “Oh, some pros are going to take this now and hack it together to get a little bit of an advantage in their competitive game or whatever.”

MK I can’t imagine how difficult this must have been to kind of get off the ground, because when it comes to especially physical accessibility, and people have different range of motions, strength, RSI, there's a lot of different things that can go into what is the perfect controller for somebody. So to create something like this that's going to have the flexibility to be able to adapt to a whole different range of people's needs is really interesting. I'm wondering kind of how that design process worked over the long term. 

CF Yeah. So I did read, like I said, they consulted with accessibility experts and people with disabilities, and I'm assuming that it was a very thorough research thing they did before they even started to build this out and they probably had it tested by a bunch of people, which is good because I've heard of a lot of devices or games or websites, whatever, technology whether it's software or hardware, that was supposed to be accessible and they didn't test it properly by having people with disabilities actually try to see if it's accessible. So I was really happy to hear that the article says that they partner with video game accessibility advocates like AbleGamers and SpecialEffect. So I think that was really good because they wanted to make sure that it's highly configurable and that it also works with accessibility devices. I'm not sure what that specifically means, but I'm assuming that for people who use motorized wheelchairs and things like that, maybe it can work in tandem with things like that. 

MK I follow one of the inaccessibility writers at Santa Monica Studios who did Ragnarock, which has been kind of lauded for its work within the accessibility space. And I'd see things pop up from time to time and they've been talking about how Microsoft has actually historically done a quite a good job with accessibility. They had this controller that came out a couple of years ago now which was designed purely for players with disabilities. 

BP Speaking of gaming, it's important to know that using only Tetris, you can build a machine capable of universal computation. I don't know how fast it would run. I don't know how well it would work, but a universal computing machine that can take any input and transform it into any output, any program, any algorithm. So if you're interested in how Tetris can become the entire backbone of your computing machine, I'll put it in the show notes. It's just one of those things that’s like, “Can I get DOOM to run on this?” It's like, “Can I get Tetris to… blank, blank, blank.” 

MK I'm having enough trouble with JavaScript as it is. I don't think I need to tackle Tetris just yet. 

BP And then the first comment takes us to Code Golf, one of my favorite Stack Exchange sites. “Build a working game of Tetris in Conway's Game of Life.” So here you have to use one universal game machine to build another universal game machine, and lots of people have submitted answers over the 10 years this question has been around. It's one of those Stack Exchange questions that basically becomes a textbook after a certain point. It just goes on forever and ever and ever. It's a beautiful thing. All right, y'all. Last but not least, we have some show news. Our dear friend Matt is going to be departing onwards and upwards from Stack Overflow. I'm sure he'll share more news with us in the future. He'll get to come back on the show. But, Matt, it has been truly a pleasure having you on. I can say that as both a guest and a host and a colleague. So tell folks a little bit about it from your perspective, and then we'll start scheming right away to get you back on

MK Yeah, it's one of those bittersweet things. I'm going to be moving on from my role at Stack Overflow as a developer advocate. I'm actually currently in search of a new opportunity, so if you're hiring a developer advocate, wanting an engineer, let me know. My email is And yeah, the last year has been absolutely fantastic. It's been a wild ride kind of coming along and being a user of Stack Overflow and then within my fourth year, I guess, within the industry, being a co-host on the Stack Overflow Podcast. That's definitely been a career highlight and something I hope I can continue to do after I have a new sign off tag– I’m Matt Kiernander at so-and-so. Maybe your company, who knows? 

BP Exactly. Excited for the new sign off tag, and I'm sure you'll have to learn a few things at the new gig which you can bring to the show. That'll be fun.

CF I have a question for you. I want to know what your favorite moment from the podcast has been. I know that's a big question, but I wonder if you've been thinking about it.

MK Yeah, okay. 

CF It can be moments. It can be more than one too, if you want.

MK Oh, I wish you'd asked me that five minutes earlier so I could have had a think. That's really hard. There've been a number of really cool moments on the show and just people that I've met. It was maybe an episode that I wasn't 100% sure of, and it ended up being something absolutely fantastic, like the home labbing episode. That was really cool. That’s something that we’ve referenced again and again. I actually think one of the conversations that I enjoyed the most was with, he started off doing Neopets to impress a girl and then that evolved. 

BP Oh, yeah. Mitchell Hashimoto. Yeah, yeah, 

MK That's the one. Yeah, Mitchell Hashimoto. That conversation was really cool because he had such an organic growth into becoming a CEO and then stepping down because he just enjoyed the tech and just wanted to kind of focus on doing things. And that whole process of leaving his job to go full-time and creating an open source project, I think that was definitely one of my favorite episodes because it's something that I guess maybe I relate to a little bit more than some of the other guests. It was very cool.

CF I agree. I liked that conversation too. 

BP That was a great one. 

MK While we're doing a quick retrospective, what were some of your highlights from last year?

CF My highlights from last year– that's a big question. I liked the home labbing episode too. I don't know if this was last year or if this was actually 2021, but every time we discuss crypto and blockchain, I really love those discussions because I feel like on Twitter it's really hard to have a productive discussion about those things because it's so polarizing and sometimes people can get mad and yada yada yada and argue and stuff. But I feel like on the podcast we were able to have differing opinions but still learn about both sides of the argument –not even argument.

MK Both sides of the coin? 

CF There we go, yeah. So I really liked those conversations. 

MK Oh, I just thought of one of my favorite episodes. It was actually talking to Cassidy's sister and her experience building the Meta VR headset. That was very, very cool as well. 

CF I also really liked the episode with Mattaniah Aytenfsu from YouTube. She was a UX designer at YouTube and also a creator on TikTok. That was really fun. Plus, I was a fan of her TikTok, so it was kind of cool to get to talk to her and meet her too. So yeah, that was cool. 

BP Yeah, that was one of our most popular episodes of the year. That one people really loved. 

CF That was really cool. 

BP Now I want to pat myself on the back more because I finally got a chance to look at our Wrapped, our year end Wrapped on Spotify, and we are one of the most followed and shared podcasts. I don't believe that for a second. I don't understand what metric they're using for that.

CF I believe it! 

BP It said it and I was like, “Sure, if you say so.” I think it's like, of people who listen to you, you have a high percentage of people who follow you and share your episodes, not numerically you are the biggest. Because that's certainly not true. 

MK I mean, if that's the case, then we should really start talking about having our own studio and signing a deal. 

BP Yeah, exactly. One of my favorite episodes was the one with the creator of Homebrew, just because it was an idea we had talked about so many times in the abstract– how can we get open source creators and maintainers paid, and doesn't the blockchain solve this somehow? And they're going to give it a try, so I appreciate that. 

MK I think if we could give an award for best voice on the podcast, that man, I'd want him to do a podcast just telling bedtime stories because I would love that. He had such a great voice. 

CF He should look into audiobooks, maybe. That would be cool.

BP An enchanting baritone.

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BP All right, y'all. Well as always, I'm going to check and see if I can find us a lifeboat badge to end the program. 

MK Oh, because we've mentioned accessibility, if anybody here is involved with accessibility for video games or is a consultant or whatever else, please email the show because we'd love to have a chat around how that whole process works and what's meaningful for you when it comes to an accessibility controller, if you've used them in the past, that kind of thing. I think it’d be a really interesting conversation. 

BP Yeah, that's a good idea. Thanks for shouting that out. All right, y’all. It is that time of the show. We want to shout out Sonu Kumar,who two days ago was awarded the lifeboat badge for coming on and saving a question from the dustbin of history by giving it a great answer. “How can I update a specific column in an active record in Ruby on Rails?” So if you're still working in Ruby on Rails and you're having trouble with your active record columns, we have an answer for you. As always, I am Ben Popper, Director of Content here at Stack Overflow. You can find me on Twitter @BenPopper. Shoot me a DM there. You can always email us, with questions or suggestions. And if you like the show, leave us a rating and a review. It really helps. 

CF And my name is Ceora Ford. I'm a Developer Advocate at Auth0 by Okta. You can find me on Twitter. My username there is @Ceeoreo_.

MK And I'm Matt Kiernander. For the last time, I'm a Developer Advocate at Stack Overflow. And you can find me online @MattKander on YouTube and Twitter. And if you want to reach out personally, it's 

BP All right. Reach out to Matt. Help him find his next great adventure. And thanks for listening, y'all. We will talk to you soon.

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