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jph

5,994 karma · joined June 2, 2010

Joel Parker Henderson

## Email ##

joel@joelparkerhenderson.com

joel.henderson@wales.nhs.uk

## Contacts ##

https://linkedin.com/in/joelparkerhenderson

https://github.com/joelparkerhenderson

https://gitlab.com/joelparkerhenderson

https://codeberg.org/joelparkerhenderson

https://facebook.com/joelparkerhenderson

https://instagram.com/joelparkerhenderson

https://orcid.org/0009-0000-4681-282X

## Open source ##

Architecture Decision Record = https://github.com/architecture-decision-record

GitAlias for git version control = http://gitalias.com

NumCommand for statistics = http://numcommand.com

UpdateCommand for system updates = http://updatecommand.com

ZidPlan for secure random data = http://zidplan.com

## Interests ###

Business e.g. tech strategy, tech tactics, tech startups.

Coding e.g. Rust, Elixir, Ruby, Python, JavaScript, Shell.

Development e.g. Agile, TDD, BDD, XP, SQA, DevOps.

## Projects ###

Software Engineering: Guide + Metrics + Code

- https://software-engineering-guide.github.io

- https://software-engineering-metrics.github.com

- https://crates.io/crates/software-engineering

Public Value: Guide + Metrics + Code

- https://public-value-guide.github.io

- https://public-value-metrics.github.com

- https://crates.io/crates/public-value

Digital Health: Guide + Metrics + Code

- https://digital-health-guide.github.io

- https://digital-health-metrics.github.io

- https://crates.io/crates/digital-health

Health Economics: Guide + Metrics + Code

- https://health-economics-guide.github.io

- https://health-economics-metrics.github.io

- https://crates.io/crates/health-economics

## Medical projects using Rust ##

Fast Healthcare Interoperability Resources (FHIR) = https://fhir-rust.github.io

Open Electronic Patient Record (openEHR) = https://openehr-rust.github.io

Systematised Nomenclature of Medicine (SNOMED) using Rust = https://snomed-rust.github.com

HL7 messages = https://hl7-rust.github.io

ER7 messages = https://er7-rust.github.io

Schematron = https://schematron-rust.github.com

submissionscomments
jph··on UUIDv7 Comes to PostgreSQL 18
We evaluated UUIDv7 and determined that it's unwise to use it as a primary key.

We have applications where we control the creation of the primary key, and where the primary key will be exposed to end users, such as when using a typical web app framework built with Rails, Phoenix, Loco, Laravel, etc. For these applications, UUIDv7 time is too problematic for security, so we prefer binary-stored UUIDv4 even though it's less efficient.

We also have applications where we control the creation of the primary key, and where we can ensure the primary key is never shown to users. For these applications, UUIDv7 is slower at inserts and joins, so we prefer BIGSERIAL for primary key, and binary-stored UUIDv4 for showing to users such as in URLs.

jph··on Vibe coding has turned senior devs into 'AI babysitters'
One improvement is to start using an AGENTS file. There are many. Here's the repo that I personally use thanks to Pontus Abrahamsson and using TypeScript:

https://github.com/pontusab/directories

If you prefer AGENTS.md files using markdown, I've extracted them into my own repo:

https://github.com/SixArm/ai-agents-tips

jph··on Modern CI is too complex and misdirected (2021)
You're 100% right IMHO about the convergence of powerful CI pipelines and full build systems. I'm very curious what you'll think if you try Dagger, which is my tool of choice for programming the convergence of CI and build systems. (Not affiliated, just a happy customer)

https://dagger.io/

jph··on Funding Open Source like public infrastructure
Yes because the work includes frequent in-person teamwork.
jph··on Launch HN: Parachute (YC S25) – Guardrails for Clinical AI
Congratulations Aria & Tony, this is much needed for healthcare. I work at UK NHS Wales in software engineering, and would be happy to talk with you personally, and also happy to introduce you to the NHS Wales AI team. Peronal email joel@joelparkerhenderson.com, work email joel.henderson@wales.nhs.uk. And we're hiring-- if anyone here is keen to code for social good healthcare, email me.
jph··on Funding Open Source like public infrastructure
Good point. We do use the existing GOV.UK design system, because it's the basis for the NHS.UK design system. Broadly, there are medical-related design aspects that use specific system quality attributes processes such as clinical compliance and formal research to help guide the look and feel and accessbility.
jph··on Funding Open Source like public infrastructure
Yes with a twist: the French government design system is purposefully reserved for the use of French government websites. I believe that a great design system will be flexible and more akin to user principles first, then implementation interface components (e.g. we need 200 or so components for one of our medical apps), then skinning such as look and feel and themeing.

As one example I'm very keen on coding techniques such headless components as by Bits UI which provides headless components for Svelte. If anyone here wants paid work to code components like these by Bits UI, come work with us. <3

jph··on Funding Open Source like public infrastructure
OpenUK is a good starting point: https://openuk.uk/

TLDR "OpenUK is a UK not for profit organisation committed to develop and sustain UK leadership in Open Technology, being open source software, open source hardware and open data, across the UK. OpenUK promotes businesses, projects and people, who use Open and strives to collaborate across all existing organisations for Open by creating a clear and loud voice for the Open Communities in the UK; influencing UK Legal and Policy to make the UK a great place for Open business and by promoting education and learning in skills in Open Technology."

jph··on Funding Open Source like public infrastructure
I lead open source projects for the United Kingdom National Health Service, specifically for NHS Wales Digital Health and Care. The UK is investing significantly in open source and publishing widely about the importance of open source.

https://www.england.nhs.uk/digitaltechnology/open-source/

If you're technical and curious, I'm currently porting the UK NHS design system from Nunjucks to more implementations, including vanilla HTML CSS TypeScript, and my personal favorite Svelte Tailwind Daisy UI. Claude Code is churning on it right now.

https://github.com/joelparkerhenderson/public-good-design-sy...

AMA. And we're hiring. Feel free to message me.

jph··on Advanced Rust macros with derive-deftly
Rust macros have so much power, yet with complexity to learn and use. IMHO your derive-deftly is finding a good balance between the power and complexity-- it's pragmatic and immediately useful.

This is excellent that you're creating this crate and sharing it. I know your company Pipedream and admire what you're doing there too.

jph··on Ask HN: What are you working on? (July 2025)
Assertables is a Rust crate for smarter assert testing, debugging, and runtime checking. Good news is it just reached 500K downloads so I'm seeking more people to try it in more kinds of use cases.

https://crates.io/crates/assertables

jph··on Ask HN: What are you working on? (July 2025)
Good work! I'm trying to sign up using joel@joelparkerhenderson.com to try it. Can you enable my account? Thanks!
jph··on Jujutsu for busy devs
Possibly means mise (https://mise.jdx.dev/) which is a tool similar to uv in the sense of managing versions.
jph··on Tools I love: mise(-en-place)
mise is a great tool. One area where it doesn't work right out of the box is installing PostgreSQL via macOS brew, when I don't want to use Nix or Docker or Podman etc.

Here's the solution I use; perhaps someone here has a better idea?

    brew install gcc readline zlib curl openssl@1.1 ossp-uuid icu4c pkg-config
    PKG_CONFIG_PATH="$(brew --prefix)/lib/pkgconfig:$(brew --prefix icu4c)/lib/pkgconfig" \
    LDFLAGS="-L$(brew --prefix)/lib" \
    CPPFLAGS="-I$(brew --prefix)/include" \
    mise use postgres --verbose
jph··on Successful people set constraints rather than chasing goals
"When John Boyd, the brilliant / irascible military strategist, developed the OODA loop, he worked within the limits of jet fighter dogfights."

Boyd is a superb recommendation for startup programmers to read. Boyd and the OODA loop can completely transform teams who aim to build software quickly.

My OODA loop notes for tech teams are here: https://github.com/joelparkerhenderson/ooda-loop

jph··on The Ingredients of a Productive Monorepo
Good practical article, thank you. I've added the link to my monorepo-vs-polyrepo guide here: https://github.com/joelparkerhenderson/monorepo-vs-polyrepo/
jph··on Show HN: Free mammogram analysis tool combining deep learning and vision LLM
Excellent work, thank you. Can you do me a favor and contact me about this? I'm joel@joelparkerhenderson.com and I'm working with public sector health care organizations that are seeking examples of AI for radiographic imaging.
jph··on Sneakers (1992) – 4K makeover sourced from the original camera negative
Sneakers and Setec Astronomy became my go to for example encryption code for years. If you're not familiar with Setec Astronomy, you're in for a treat. <3
jph··on Using fake deadlines without driving your engineers crazy
Fake deadlines suck. They cut against high-trust teamwork. They obscure real deadlines, including real commitments to customers.

The author writes "Once I became a manager, I finally saw why they were needed, but felt guilty about using them."

You SHOULD feel guilty. Truth matters. Trust matters.

If you're having problems with estimation and planning, then success looks like working on these areas-- not faking them.

Good tactics to try are work breakdown structures, planning poker, transparency for timelines, good project management tooling, critical chain scheduling, and above all trusting your teammates.

jph··on Show HN: Simple SWE agent in 72 lines of code (using Dagger)
Dagger is so great! It's my favorite new tool for devops and CI/CD/CT. If you've ever wrestled with anything like Jenkins or GitHub Actions, then give Dagger a try. This SWE agent is a perfect example of why Dagger is more powerful, more flexible, and makes more sense than typical devops IaC. (I'm not affiliated with Dagger, merely really happy about it)
jph··on Ask HN: Can I really create a company around my open-source software?
Great software. I can pay you, if you're able to do professional services work implement forms.md within a startup codebase, in both Django and Svelte. Email joel@joelparkerhenderson.com.
jph··on I helped fix sleep-wake hangs on Linux with AMD GPUs
Your work will help me on a Framework AMD laptop with the GPU extension and dual boot Linux/Windows. May I donate to you or to your favorite charity? My contact info is in my profile.
jph··on NASA has a list of 10 rules for software development
Read the original and it explains the purpose of each item:

https://spinroot.com/gerard/pdf/P10.pdf

The original clearly describes that the coding rules primarily target C and attempt to optimize the ability to more thoroughly check the reliability of critical applications written in C. The original author clearly understands what they're doing, and explains lots of other ways to verify C code.

For what it's worth, the rationales in the original all make perfect sense to me. Perhaps this is because I learned C on tiny systems? I learned C for hardware for implanted medical devices, and our lab did similar kinds of guidelines.

jph··on Show HN: Hollow – A Customizable Digital Workspace
Think about adding screenshots of people using it, or explainer videos, or before/after comparisons, etc.

You'll likely land more people if you can provide context. For example, is it kind of like Notion, or Airtable, or HyperCard, or Trello? Is there a specific kind of person, or role, or task that is an especially good match?

jph··on $1000 bug bounty for better healthcare with the FDA, CDC, and Kaiser Permanente
In progress. The next step is February 11 meeting with the site lead doctor.
jph··on Ask HN: Would you still choose Ruby on Rails for a startup in 2025?
Yes Rails 8 is great. However, pick what the team knows best. For example at a startup doing AI/ML where everyone already knows Python and we're doing a lot with Pandas and Jupyter, we're choosing to build our website CMS by using Django & HTMX.

BTW shoutout to the Loco team, for my favorite new web framework. If you're already working with Rust in general, and your business requires extreme speed and extreme reliability-- beyond simple horizontal scaling CPU/GPU/K8-- then take a look at the stack of Loco + Axum + Tokio + Rust.

jph··on $1000 bug bounty for better healthcare with the FDA, CDC, and Kaiser Permanente
Hi Arun! Good to hear from you. I'm so sorry to hear about your people affected by the wildfires. I'll reply to you directly. Thank you so much for sharing this! <3
jph··on $1000 bug bounty for better healthcare with the FDA, CDC, and Kaiser Permanente
Yes that's what I thought too. It turns out that doctors who are talking with me believe that their EPIC IT system is no longer able to do paper orders, and the vaccination nurses say there's no way to obtain the physical vaccine without a coded order.

Everyone on staff tells me variations of fearing being fired or losing their license or employer retribution if anyone attempts workarounds.

jph··on Ask HN: How to approach first days on a new job as a senior PM?
I maintain a repo of topics for new PMs, plus one-page explanations, in web page format and also as a free ebook. Constructive feedback welcome.

https://github.com/sixarm/project-management-guide

This guide doesn't tell you what to do; it give you much of the lingo and a bunch of framework choices that you can use, or perhaps that the existing teammates are already using.

jph··on Tabby: Self-hosted AI coding assistant
IMHO companies should aim for courteous interviews, with faster decisions, and if there's any take home work then it's fully paid. I've seen your work at Beaver.digital and on GetFractals.com. If you're still looking, feel free to contact me; I'm hiring for a startup doing AI/ML data analysis. Specifically Figma + DaisyUI + TypeScript + Python + Pandas + AWS + Postgres.
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