Emacs Lisp shorthands as namespacing system

In Emacs version 28 Emacs developers introduced so-called read symbol shorthands. If you’re interested in the rationale, feel free to search the Emacs developer mailing list for the discussion. However, it does seem that not everyone likes the idea of shorthands as a substitution for namespaces (or packages, if you’re coming from Common Lisp).

Source: Emacs Lisp shorthands as namespacing system, an article by Andrey Listopadov.

Data-oriented Programming in Python

Many users of Python deprioritize performance in favor of soft benefits like ergonomics, business value, and simplicity. Users who prioritize performance typically end up on faster compiled languages like C++ or Java.

One group of users is left behind, though. The scientific computing community has lots of raw data they need to process, and would very much like performance. Yet, they struggle to move away from Python, because of network effects, and because Python’s beginner-friendliness is appealing to scientists for whom programming is not a first language. So, how can Python users achieve some fraction of the performance that their C++ and Java friends enjoy?

Source: Data-oriented Programming in Python, an article by Brian Kihoon Lee.

Cache invalidation

My colleagues recently wrote a great post on the Netflix tech blog about a tough performance issue they wrestled with. They ultimately diagnosed the problem as false sharing, which is a performance problem that involves caching.

I’m going to take that post and write a simplified version of part of it here, as an exercise to help me understand what happened. After all, the best way to understand something is to try to explain it to someone else.

Source: Cache invalidation really is one of the hardest problems in computer science, an article by Lorin Hochstein.

You can program functionally in any computer language

A few days ago I wrote a comment on The Orange Site that seemed to strike a chord there. The comment was about applying a few principles of functional programming in any language (well, maybe not BASIC from the 70s or 80s, but these versions of BASIC aren't used much these days). There's no need for functional application, functional composition, first class functions, monads, (“Monads! How do they work?”) or even currying. No, I feel like you can get about 85% of the way to functional programming by following three simple principles.

Source: You can program functionally in any computer language, an article by Sean Conner.

Test factory functions in Django

When writing tests for Django projects, you typically need to create quite a lot of instances of database model objects. This page documents the patterns I recommend, and the ones I don’t.

Before I get going, I should mention that a lot of this can be avoided altogether if you can separate out database independent logic from your models. But you can only go so far without serious contortions, and you’ll probably still need to write a fair number of tests that hit the database.

Source: Test factory functions in Django, an article by Luke Plant.

Fall (2022)

Best friends Becky and Hunter find themselves at the top of a 2,000-foot radio tower.

In the evening Esme and I watched Fall. At first I was not sure if I would be able to watch the movie because I am very afraid of heights. But with only one short break I managed to watch the whole movie. I liked it and give the movie a 7 out of 10.

Feature Switch Best Practices

One of the best things to come out of the modern DevOps movement is the aggressive push for “feature switches” (also known as “feature flags” or “feature toggles”). At All Around the World , we strongly recommend them for our clients and sometimes we implement them, but I’m still surprised that many companies don’t use them. They’re dead-simple to build and they’re a powerful tool for site reliability. Unfortunately, many articles discuss how to build them or use them, but best practices are neglected. So we’ll skip the implementation and instead focus on using feature switches effectively.

Source: Feature Switch Best Practices, an article by Curtis "Ovid" Poe.

Linux’s Traceroute

The other day I just wanted to capture some basic Linux traceroutes but ended up troubleshooting different traceroute commands and Wireshark display anomalies.

Source: Linux’s Traceroute, an article by Johannes Weber.

Pattern Matching and Tail Recursion in Emacs Lisp

Functional programming offers a bunch of really cool programming patterns. Two that I really enjoy are tail recursion and pattern matching, especially how they are implemented in OCaml. However, I spend a lot of time writing Emacs Lisp now, and I was wondering if I could find a way to use these patterns in that language.

It turns out that it is possible, thanks to named-let and pcase. It isn’t as pretty and elegant as OCaml, but at least I get to keep excercising those parts of my programming brain. Maybe next I’ll try to figure out currying in Emacs Lisp.

Source: Pattern Matching and Tail Recursion in Emacs Lisp, an article by Erik L. Arneson.

Using Rust at a startup: A cautionary tale

I hesitated writing this post, because I don’t want to start, or get into, a holy war over programming languages. (Just to get the flame bait out of the way, Visual Basic is the best language ever!) But I’ve had a number of people ask me about my experience with Rust and whether they should pick up Rust for their projects. So, I’d like to share some of the pros and cons that I see of using Rust in a startup setting, where moving fast and scaling teams is really important.

Source: Using Rust at a startup: A cautionary tale, an article by Matt Welsh.

Installing Mastodon inside a FreeBSD jail

I'll describe a simple, one jail installation, not security oriented nor explaining any single option. If you're managing an instance, you should be skilled enough to understand what you're doing here. It would be better to separate the services (Redis, PostgreSQL, etc.) but, for simplicity, I'll just put everything in a nice single (movable) jail.

Source: Installing Mastodon inside a FreeBSD jail, an article by Stefano Marinelli.

OpenBSD for Linux Users

This quickstart guide is intended to quickly familiarize GNU/Linux users with the basics of OpenBSD and will highlight some of the technical differences between OpenBSD and the various GNU/Linux based distributions. It is not intended to be an exhaustive list of differences, nor will it highlight the rather large philosophical differences between OpenBSD and GNU/Linux.

Source: OpenBSD for Linux Users.

12 Strong (2018)

12 Strong tells the story of the first Special Forces team deployed to Afghanistan after 9/11; under the leadership of a new captain, the team must work with an Afghan warlord to take down the Taliban.

In the evening I watched 12 Strong. I liked the movie and give it a 7.5 out of 10.

A Better Way to Borrow in Rust: Stack Tokens

As a Rust programmer you are probably quite familiar with how references work in Rust. If you have a value of type T you can generally get various references to it by using the ampersand (&) operator on it. In the most trivial case &T gives you just that: a reference to T. There are however cases where you can get something else. For instance String implements Deref<Target=&str> which lets you also get a &str from it and that system also can be extended to work with mutable references as well.

Source: A Better Way to Borrow in Rust: Stack Tokens, an article by Armin Ronacher.

Safely writing code that isn't thread-safe

One of the nice things about the Rust programming language is that it makes it easier to write correct concurrent (e.g. threaded) programs – to the degree that Rust’s slogan has been, at times, “fearless concurrency.”

But I’d like to tell you about the other side of Rust, which I think is under-appreciated. Rust enables you to write programs that are not concurrent. This feature is missing from most other languages, and is a source of much complexity and bugs.

Source: Safely writing code that isn't thread-safe, an article by Cliff L. Biffle.

The Dragonbone Chair

A war fueled by the powers of dark sorcery is about to engulf the peaceful land of Osten Ard—for Prester John, the High King, lies dying. And with his death, the Storm King, the undead ruler of the elf-like Sithi, seizes the chance to regain his lost realm through a pact with the newly ascended king. Knowing the consequences of this bargain, the king’s younger brother joins with a small, scattered group of scholars, the League of the Scroll, to confront the true danger threatening Osten Ard.

Simon, a kitchen boy from the royal castle unknowingly apprenticed to a member of this League, will be sent on a quest that offers the only hope of salvation, a deadly riddle concerning long-lost swords of power. Compelled by fate and perilous magics, he must leave the only home he’s ever known and face enemies more terrifying than Osten Ard has ever seen, even as the land itself begins to die.

In the morning I started in The Dragonbone Chair, book one of Memory, Sorrow, and Thorn by Tad Williams.

Always use [closed, open) intervals

Intervals or ranges pop-up everywhere in the programming world. The classic example is picking a start and end date, like you would when booking an AirBnB or a flight. But that's just one example: from slicing a JS Array, to Java's List#sublist and even SQL's LIMIT operator, ranges are everywhere.

Have you ever wondered why they are always implemented as [closed, open) as opposed to [closed, closed]?

Source: Always use [closed, open) intervals. A programmer's perspective, an article by Fernando Hurtado Cardenas.

Deploying Nix-built containers to Kubernetes

While it’s easy to fall in love with Nix and want to use it to build and configure just about everything, let’s face it: few of us are in a position to do so, especially in the workplace. “Hey team, let’s Nixify our entire stack!” is unlikely to endear you to your coworkers at daily standup. Fortunately, Nix is good at enough things that you can reap many of its potential benefits by incorporating it into only a subset of an already existing software pipeline.

In this post, I’ll provide a concrete example of this by using Nix inside a fairly standard DevOps pipeline that builds Docker images and deploys them to Kubernetes in CI. Nix does a lot of heavy lifting in this scenario but it doesn’t do everything: it doesn’t stand up any infrastructure and it doesn’t handle deployment. That’s all left to popular, trusted tools and platforms from outside the Nix universe. I hope that this example inspires you to find ways to incrementally introduce Nix into your own stacks.

Source: Deploying Nix-built containers to Kubernetes, an article by Luc Perkins.

Reed-Solomon Error Correcting Codes from the Bottom Up

I’ve always been intimidated by coding techniques: encryption and decryption, hashing operations, error correction codes, and even compression and decompression techniques. It’s not that I didn’t know what they do, but I often felt that I never quite understood the basics, let alone had an intuitive understanding of how they worked.

Reed-Solomon forward error correction (FEC) is one such coding method. Until the discovery of better coding techniques (Turbo codes and low-density parity codes), it was one of the most powerful ways to make data storage or data transmission resilient against corruption: the Voyager spacecrafts used Reed-Solomon coding to transmit images when it was between Saturn and Uranus, and CDs can recover from scratches that corrupt up to 4000 bits thanks to the clever use of not one but two Reed-Solomon codes.

Source: Reed-Solomon Error Correcting Codes from the Bottom Up, an article by Tom Verbeure.

A history of ARM, part 2

The story so far: At the end of the 1980s, Acorn Computers was at a crossroads. A small team, led by Sophie Wilson and Steve Furber, had invented a powerful new computer chip, the Acorn RISC Machine (ARM). Acorn released a new computer line, the Archimedes, that used these ARM chips. But the world wasn’t beating a path to the company's door.

Source: A history of ARM, part 2: Everything starts to come together, an article by Jeremy Reimer.

Prey (2022)

Naru, a skilled warrior of the Comanche Nation, fights to protect her tribe against one of the first highly-evolved Predators to land on Earth.

In the evening we watched Prey. I liked the movie a lot and give it an 8 out of 10.

Swift project in 2023

There’s a lot of exciting work going on in the Swift project, and it’s hard to keep track of it all because it’s happening in many different repositories, pull requests, and forum threads. To give the community a better view of the big picture, the Core Team surveyed workgroups and developers across the project and collected information about what they’re focused on over the next year.

Please keep in mind that nothing here is a lock for any particular release of the project — plans and priorities can change over time. This also isn’t an exhaustive list of everything happening in the project. But we hope you find this interesting and informative, and if you have questions about any of these areas, please feel free to reach out and ask for more details.

Source: Swift project in 2023, an article by John McCall.

How to use a Raspberry Pi in kiosk mode

Kiosks are designed to offer users specific information or a specific experience, while preventing access to any other activities on the device. They are often found in airports, shops, hospitals, cafes, and museums — any location where people need easy access to information or services like timetables, waiting times, product information, directions, self check-in machines, and so on.

Kiosk mode on your Raspberry Pi allows you to boot straight into a full-screen web page or an application without using the desktop environment. It’s the foundation for many different projects where you want to display information for a dedicated interaction with a user.

Source: How to use a Raspberry Pi in kiosk mode.

Tree views in CSS

A tree view (collapsible list) can be created using only HTML and CSS, without the need for JavaScript. Accessibility software will see the tree view as lists nested inside disclosure widgets, and the standard keyboard interaction is supported automatically.

Source: Tree views in CSS, an article by Kate Rose Morley.

A from-scratch tour of Bitcoin in Python

I find blockchain fascinating because it extends open source software development to open source + state. This seems to be a genuine/exciting innovation in computing paradigms; We don’t just get to share code, we get to share a running computer, and anyone anywhere can use it in an open and permissionless manner. The seeds of this revolution arguably began with Bitcoin, so I became curious to drill into it in some detail to get an intuitive understanding of how it works. And in the spirit of “what I cannot create I do not understand”, what better way to do this than implement it from scratch?

We are going to create, digitally sign, and broadcast a Bitcoin transaction in pure Python, from scratch, and with zero dependencies. In the process we’re going to learn quite a bit about how Bitcoin represents value. Let’s get it.

Source: A from-scratch tour of Bitcoin in Python, an article by Andrej Karpathy

Switching between SwiftUI’s HStack and VStack

SwiftUI’s various stacks are some of the framework’s most fundamental layout tools, and enable us to define groups of views that are aligned either horizontally, vertically, or stacked in terms of depth.

When it comes to the horizontal and vertical variants (HStack and VStack), we might sometimes end up in a situation where we want to dynamically switch between the two. For example, let’s say that we’re building an app that contains the following LoginActionsView, which lets the user pick from a list of actions when logging in.

Source: Switching between SwiftUI’s HStack and VStack, an article by John Sundell.

Demystifying Fourier analysis

I've started learning about spectrum analysis a long time ago at university, but failed to gain a true insight in how it works under the hood. For me, it was just some magical math formulas I had to memorize and know about. I knew the theory but it didn't really "click".

A few years ago I wanted to do some audio programming and play around with analyzing sound. That's how I got interested into building an intuition on how the Fourier transform "actually" works.

Source: Demystifying Fourier analysis, an article by Davorin Šego.

Perl is Actually Portable

After stumbling upon Gautham's APE Python port and seeing how far along the Cosmopolitan Libc has come along, I was inspired to see what it would take to port my scripting language of choice, Perl, to the Cosmopolitan Libc and turn it into a self-contained binary. My motivation came from wanting to prove that if Python can do it, Perl can do it too, wanting a more robust Windows Perl port for running my personal media server (MHFS), and the cool factor of hacking on Perl and the Cosmopolitan Libc.

Source: Perl is Actually Portable, an article by Gavin Hayes.

Who controls parallelism? A disagreement that leads to slower code

If you’re using NumPy, Polars, Zarr, or many other libraries, setting a single environment variable or calling a single API function might make your code run 20%-80% faster. Or, more accurately, it may be that your code is running that much more slowly than it ought to.

The problem? A conflict over who controls parallelism: your application, or the libraries it uses.

Source: Who controls parallelism? A disagreement that leads to slower code, an article by Itamar Turner-Trauring.

Building TUIs with textual: first impressions

Last week, I finally started exploring textual. The main motivation was to start implementing a few project ideas I've had in my todo list for years. I don't particularly have a preference between TUI (terminal user interface) and GUI (graphical user interface) for these projects. Seeing a few Textual demos on twitter (courtesy Will McGugan) over the past few months, I felt like exploring this framework first.

Source: Building TUIs with textual: first impressions, an article by Sundeep Agarwal.

ABI compatibility in Python: How hard could it be?

Trail of Bits has developed abi3audit, a new Python tool for checking Python packages for CPython application binary interface (ABI) violations. We’ve used it to discover hundreds of inconsistently and incorrectly tagged package distributions, each of which is a potential source of crashes and exploitable memory corruption due to undetected ABI differences. It’s publicly available under a permissive open source license, so you can use it today!

Source: ABI compatibility in Python: How hard could it be?.

80/20 Refactoring

I have found a new bugbear. Something to be creatively annoyed about. I’m going to call it 80/20 refactoring, to express the idea that a refactoring is started, but then not finished. Probably because doing all of the edge cases in a refactoring is hard.

Source: 80/20 Refactoring, an article by Adriaan De Groot.

Staged programming with typeclasses

Staged programming consists of evaluating parts of a program at compile time for greater efficiency at runtime, as some computations would have already been executed or made more efficient during compilation. The poster child for staged programming is the exponential function: to compute a^b, if b is known at compile time, a^b can be replaced by b explicit multiplications. Staged programming allows you to write a^5, but have the expression compile to a*a*a*a*a.

Source: Staged programming with typeclasses, an article by Thomas Bagrel.

Desert Star

A year has passed since LAPD detective Renée Ballard quit the force in the face of misogyny, demoralization, and endless red tape. But after the chief of police himself tells her she can write her own ticket within the department, Ballard takes back her badge, leaving “the Late Show” to rebuild and lead the cold case unit at the elite Robbery-Homicide Division.

For years, Harry Bosch has been working a case that haunts him—the murder of an entire family by a psychopath who still walks free. Ballard makes Bosch an offer: come volunteer as an investigator in her new Open-Unsolved Unit, and he can pursue his “white whale” with the resources of the LAPD behind him.

First priority for Ballard is to clear the unsolved rape and murder of a sixteen-year-old girl. The decades-old case is essential to the councilman who supported re-forming the unit, and who could shutter it again—the victim was his sister. When Ballard gets a “cold hit” connecting the killing to a similar crime, proving that a serial predator has been at work in the city for years, the political pressure has never been higher. To keep momentum going, she has to pull Bosch off his own investigation, the case that is the consummation of his lifelong mission.

The two must put aside old resentments and new tensions to run to ground not one but two dangerous killers who have operated with brash impunity. In what may be his most gripping and profoundly moving book yet, Michael Connelly shows once again why he has been dubbed “one of the greatest crime writers of all time” (Ryan Steck, Crimereads).

In the evening I started in Desert Star, a Renée Ballard and Harry Bosch novel by Michael Connelly.

Taking off with Nix at FlightAware

At the time of writing, most articles on the Nix package manager are written with individuals or small teams in mind. Unfortunately, these articles do not offer much insight or advice on adopting Nix across an entire engineering organization. This blog post is our attempt to fix that.

Source: Taking off with Nix at FlightAware, an article by Andrew Brooks.

Python, Catastrophic Regular Expressions and the GIL

The other day at work one of our python processes stopped responding. It was on one of our servers that was responsible for fetching and analyzing the web pages that we might recommend to people.

By the time I got around to debugging this problem, the last log message was over 20 minutes old - and the server had been maxed out at 100% CPU for the whole time. And while it wasn’t dead, it wasn’t responding to any requests, or even sending out any heartbeats. Even worse, in the meantime this problem had repeated itself on another server. Our whole ability to ingest new web pages looked to be going down one server at a time.

Source: Python, Catastrophic Regular Expressions and the GIL, an article by Ben Frederickson.