xxix · ix · mmxxvi

Hello, again

I codify contracts between systems for a living, in Rust and Python. I once spent five years chasing where the antimatter went.

Senior software engineer at PactFlow (SmartBear). I help lead the open-source Pact Foundation and maintainpact-python; I also wrote tikz-feynman,rust-skiplist, and more.

Previously: data and cloud engineering at KPMG, and doctoral research in theoretical particle physics.

The year in code

4393 commits, 684 PRs, and 231 issues across 34 repositories.

Sep 2025 — Sep 2026
Most of what I make is open. Each square below is one day of my GitHub contributions over the past year.

Latest commits

JP-Ellis/borrow-checkerdocs(design): list the web server as a surface18h
JP-Ellis/borrow-checkerrefactor(bc-service): share the display lookups21h
JP-Ellis/borrow-checkerfix(bc-ui): require a reload after a failed refetch21h
JP-Ellis/borrow-checkerdocs(bc-ipc): list get_transaction's Validation error21h
JP-Ellis/borrow-checkerfix(bc-core): log a transaction edit after commit22h
JP-Ellis/borrow-checkertest(bc-core): race a stale edit with a writer22h

Latest issues & PRs

JP-Ellis/borrow-checker[PR · open]
perf(mise): erase Leptos view types in debug wasm14h
JP-Ellis/dotfiles[PR · merged]
feat(mise): add forgejo-cli17h
JP-Ellis/dotfiles[PR · merged]
feat(dotter): default EDITOR and VISUAL to nvim21h
JP-Ellis/borrow-checker[PR · open]
docs: document the hosted server23h

Selected projects

pact-pythonOSS · libraryPython bindings for Pact, rebuilt over a Rust FFI core. Downloaded over 1.3 million times a month.↗ github
tikz-feynmanOSS · LaTeXA LaTeX package for typesetting Feynman diagrams with TikZ; adopted across particle physics with 400+ academic citations.↗ github
rust-skiplistOSS · libraryA skip list for Rust.↗ github
↗ All projects