week 47, 2022

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.