qr codes

Veritasium builds a QR code by hand to explain how it works. It covers the history of Morse code and barcodes, how QR codes encode data, why damaged codes still scan, and how safe they are.

MattKC fits a playable Snake game into a QR code by writing tiny x86 machine code and patching the ZBar scanner so it can run the decoded data.

3Blue1Brown's discovery-oriented introduction to error correction codes, building up Hamming codes from the puzzle of locating a flipped bit. It explains the parity-check idea and why it is so efficient.

Greg Young, who coined CQRS, looks back on a decade of domain-driven design, CQRS and event sourcing at DDD Europe 2016. He discusses where event sourcing applies and how simple its core can be.

A sketch from the Seattle comedy show Almost Live! in which Pat Cashman plays a US Bell rep explaining the new 425 area code. It first aired in 1997.

Cliff Click of Azul Systems gives a Google Tech Talk on running Java business applications on a machine with about a thousand cores. He covers hardware and software codesign, including garbage collection hardware and the JIT.

Greg Young's Code on the Beach 2014 talk on CQRS and event sourcing. He argues mature domains are built on facts that occurred rather than current state, and covers the business and technical benefits.

CGP Grey explains that postal codes are routing instructions for mail rather than geographic regions. He looks at the quirks and problems this causes.

A DEF CON 29 talk by Richard Henderson about encoding the EICAR antivirus test string into QR codes and barcodes and scanning them at real systems. Many systems that do not expect such input misbehave or collapse, including a parking garage system.

CGP Grey explains why airport codes are inconsistent and sometimes confusing, from their origins in old weather station codes to the quirks that cause mistakes. He builds the story around a single typo that sent a flight to the wrong continent.

David Beazley's PyCon India closing keynote, in which he live-codes a stack machine and grows it into an interpreter that runs WebAssembly, then uses it to play a Rust-written game. It requires no prior WebAssembly knowledge.

Irving Finkel of the British Museum lectures at the Royal Institution on the invention and decipherment of cuneiform writing in Mesopotamia, and why it is so hard to translate.

About Here explains how North American building codes requiring two staircases make small multi-story apartment buildings hard to build, and contrasts this with places that allow single-stair designs.

Ben Eater explains how the PS/2 keyboard interface works, covering its clocked serial protocol and scancodes. He builds up the hardware-level understanding needed to read keypresses.

Greg Young, who coined CQRS, gives an in-depth GOTO 2014 talk on what event sourcing is, when it is valuable and when it is not, along with its trade-offs and common misconceptions.

Martin Kleppmann's Kafka Summit 2018 keynote asks whether Kafka can be considered a database. He covers event logs and related data-systems ideas.

Reason TV profiles Elvis Summers, a Los Angeles musician who crowdfunded dozens of tiny homes for homeless people. City officials moved to remove them while pushing a multibillion-dollar housing plan.

Inigo Quilez live-codes a cartoon character painting entirely from math, using signed distance fields in a Shadertoy shader. He explains each step of building the image from formulas.

Dan Abramov live-codes hot reloading with time-travel debugging at React Europe 2015, debuting Redux and its devtools. The slides themselves are driven by application state.

Liz Rice live-codes a minimal container runtime in a few lines of Go at GOTO Amsterdam 2018. She explains namespaces, control groups and what a host knows about its containers.

Bruce Hauman live-codes Flappy Bird in ClojureScript in about six minutes, using figwheel to hot-reload changes into the running game. The demo shows game behavior being changed interactively without restarting.

A recording of Andres Duany's 1991 'San Antonio By Design' seminar on suburban sprawl. He lays out how codes, zoning and policy produce sprawl and makes the case for new urbanism.

Grant Sanderson of 3Blue1Brown shows his workflow for animating math videos with Manim, with Ben Sparks. He codes scenes live, including a Lorenz attractor, and walks through example scenes.

Andrew Sorensen's OSCON 2014 keynote in which he live-codes generative music on stage using his Impromptu environment while narrating his computational and musical choices. It imagines concert programmers as a performing art.

John Carmack live-codes a simple VR application at Oculus Connect 2 using a Racket-based environment for rapid development and deployment on Gear VR.

Inigo Quilez live-codes a painting using only mathematics in a shader, building it up step by step. The linked Shadertoy source shows the result.

Sam Aaron live codes an ambient electronic set using Sonic Pi, the music programming environment he created. The performance shows code driving music in real time.

Tsoding live-codes a JSON parser from scratch in Haskell in about 111 lines, using only the standard library. It is an edited Twitch stream that explains the intuition behind parser combinators, functors, applicatives and monads.

In this first Crust of Rust episode, Jon Gjengset live-codes an example that needs multiple explicit lifetime annotations. Along the way he covers string types and generics over a custom trait.

Inigo Quilez live-codes the "Happy Jumping" animated scene in a Shadertoy GLSL shader over about six hours. He builds the raymarched character step by step, explaining the math and procedural techniques, with checkpoints linked for each stage.

Nathaniel J. Smith's PyCon 2018 talk introducing Trio, a Python concurrency library designed around usability and structured concurrency. He live-codes a problem and analyzes pitfalls in other async libraries.

Tom Dale explains the internals of the Glimmer VM, Ember's rendering engine, which compiles templates to opcodes. The talk includes a performance benchmark demo.

A short side-by-side demo of a large image loading over a slow connection in JPEG, progressive mozjpeg, JPEG XL and AVIF. It shows how each codec renders partial data.

Samuel Falvo II live-codes a text preprocessor and blog engine in Forth over about an hour. It shows Forth's dictionary being snapshotted and restored in place of mutation, and how a small Forth system gets real work done.

Andreas Kling live-codes a prototype JavaScript JIT compiler for the LibJS engine used in SerenityOS and Ladybird. He builds a standalone bytecode VM, a simple interpreter, and then a simple JIT in about 80 minutes.

A short FIRE-published video of Yale students confronting a faculty member over a Halloween costume email in 2015. It documents a heated campus protest.

A short clip of Venetian Snares' track 'Look' from Songs About My Cats (2001), shown as a spectrogram. The audio encodes an image in its frequency content.