Hacker's Handbook

The Handbook

The Hacker's Handbook is the essay archive of HappiHacking. It collects notes on BEAM systems, architecture, runtime behavior, technical leadership, and production work.

Some posts are polished essays. Others are field notes, old project memories, course fragments, or strange little maps of how systems behave under pressure.

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Staff, Not Author How I use AI for my books by Happi
From Markdown to Print One source pipeline that produces both PDF and ebook. by Happi
The Words You Do Not Have In 1987 English made me faster and stupider in the same week. Last month a reader caught it happening to my novel. by Happi
Why I Wrote a Tech Thriller The hacking was never the unrealistic part by Happi
When Exports Become Accidental APIs Visibility domains and architectural drift on the BEAM by Happi

Archive

2026

The Shared State of Isolation. Why Systems Collapse Under Load (and How to Fix It) by Happi
Your Code Has No Memory From code change to intent, there and back again by Happi
The Late-Night Feeling of Wonder by Happi
Why I Built a Course on the BEAM Understanding the runtime changes how you build on it. by Happi

2025

Observers: The Watchful Gnomes of the Village Processes that watch, restart, and enforce lifetimes by Happi
Gatekeepers: The Traffic Controllers of the Gnome Village Processes that protect the system from the outside world, and from itself by Happi
Routers: Processes That Only Decide Where Stuff Goes The Gnome Village Mailmen by Happi
Resource Owners: One Process, One Piece of State The boring, reliable center of most good systems by Happi
Workers: Do One Job, Then Get Out of the Way Short-lived processes, polite pools, and where people overcomplicate things by Happi
Process Archetypes: The Roles in the Gnome Village Every process has a job. Problems start when it has two. by Happi
Gnomes, Domains, and Flows: Putting It Together From checklist to a running payments path by Happi
Flows Keep Work Moving Design data, message, process, and call paths on purpose by Happi
Domains Own Code and Data Keep modules, OTP apps, and state in the same lane by Happi
Gnomes, Domains, and Flows Why boundaries decide whether the village holds by Happi
Supervisors Are Managers Build a village of gnomes, not a park of machines. by Happi
The Gnome Village Threads fight. Gnomes cooperate. by Happi
Exposing the 'Multibank Crypto Poker' Recruitment Scam If it looks too good to be true, it is by Happi
Exactly once Exactly once by Happi
Assembler, Stepper Motors, and a Hotel Pool Revisiting the animatronic spy drama of Haparanda Stadshotell, three decades later by happi
Why I Wrote the BEAM Book Post-mortems, coffee, and a decade of stubborn curiosity by Happi
Your Finance Stack Is Lying to You Accidental Complexity in Fintech by Happi
AI Rubber Ducking: When Your Duck Starts Talking Back Debugging with an AI duck that asks questions back by Happi
The BEAM Book Is Almost Done. Here's What Writing It Taught Me. Reflections on scope, clarity, and the joys of letting go. by Happi
Why Some Fintechs Scale Seamlessly; and Others Crash and Burn Most fintech backends break under pressure. Yours doesn't have to. by Happi
Summon Your AI Sidekick: Building a Tireless Personal Coach When Your AI Coach is Named Orrin by Happi
The Best Issue Ever Reported on GitHub This one's a feature, definitely not a bug by Happi
Hyperchains: Your Own L1 with Aeternity Tech Set Your Own Fees, Scale Without Limits by Happi
Synchronous vs. Asynchronous: Clearing the Confusion Messaging, APIs, RPC, and Other Buzzwords Explained by Happi
RabbitMQ Reliability: A Reality Check Reliability depends on topology, guarantees, and operations. by Happi
Forget Microservices: Just Use Erlang. A distributed system, without the distributed headaches. by Happi
The Hidden Cost of Bad Payment Architecture Because 'It Works' Is Not the Same as 'It Works Well' by Happi
Opinions: Just the Facts, 11 Years Later Still no opinions. Mostly. by Happi
Microservices Are NOT an Excuse for Chaos How Overcomplicating Your Architecture Can Destroy Scalability Instead of Enabling It by Happi
Getting the hang of Rebar3 by Richard

2024

Why Windows 11 Virtual Desktop Switching Is Slow And How to Fix It by Happi
Developer Productivity for Early-Career Engineers A course note for newer developers by Happi
Developer Productivity for Experienced Engineers A course note for senior developers by Happi
Developer Productivity Notes on attention, workflow, and engineering habits by Happi
Dev Containers Part 3: UIDs and file ownership by Richard
Enhancing Fintech Security with Erlang Build Scalable and Reliable Fintech Systems with Erlang by Happi
How Erlang Powers High-Volume Finance Build Scalable and Reliable Fintech Systems with Erlang by Happi
TIPS and RIX-Inst: Navigating the Future of Real-Time Payments in the EU Opportunities and Challenges for Fintech Companies by Happi
Developer Types Addressing the Elephant in the Room by Happi
The Quest for Enhanced Productivity in Software Development A Reflection One and a Half Decades Later by Happi
Designing Concurrent Systems on the BEAM Principles and Strategies for Robust System Design by Happi

2023

Three Decades with Erlang A Personal Odyssey by Happi
Recovering from a Hacked Social Media Account A Quick Guide by Happi
Dev Containers Part 2: Setup, the devcontainer CLI & Emacs Bring Your Emacs Friends to the Party by Max
Dev Containers: Consistency in Development Finding Freedom in Confinement by Happi
Seamless Productivity with Mouse without Borders A Happi Hacker's Dream by Happi
Neural Networks in Elixir A beginners guide by Happi
AI Laser Metal Cutting - Part 3 Replacing humans by AI optimization as a service by Jim Wilenius
AI Laser Metal Cutting - Part 2 Replacing humans by AI optimization as a service by Jim Wilenius
AI Laser Metal Cutting - Part 1 Replacing humans by AI optimization as a service by Jim Wilenius
Audits through Merkle Root Hashes Blockchain - The good parts by Tobias
It is never about technology - until it is Then it is Erlang by Happi
Book Review "The Goal - A Process of Ongoing Improvement" by Eliyahu M. Goldratt and Jeff Cox Unleashing the Power of the Theory of Constraints on Software Development by Happi
Taba the story by Happi
How We Designed FATE A smart contract virtual machine for the æternity blockchain by Happi
Unleashing the Power of Erlang's BEAM A case study with Delta Exchange by Happi
Rapid Prototyping Building a production ready MVP in 3 months by Happi
Taming the Spaghetti Monster: The Birth of Kappa Solving Codebase Complexity at Klarna with a Business Layers Strategy by Happi
The Happy Path Method Start with the path that proves the system. by Happi
HappiHacking's Just in Time Development An Agile Success Story with Klarna's Installment Plans by Happi
Unlocking Performance: Introducing HappiHacking's New Course on BEAM by Happi

The BEAM Book • Contact Erik