Jimmy Hartzell
Software Engineer at Two Sigma
Phoenixville, Pennsylvania, United States
Summary
🤩
Rockstar🎓
Top SchoolJimmy Hartzell is a seasoned software engineer with 17 years of experience building high-performance systems across trading, embedded, and web domains. Currently at Two Sigma after a senior principal role at Amtrak, he brings deep expertise in systems programming, Rust, C++, and low-latency architectures alongside hands-on work in embedded Linux and mobile. He has led teams, taught C++ and systems programming, and migrated legacy stacks to modern runtimes—rewriting Swift services into Rust and authoring a usermode Rust driver for an energy meter. An active contributor to open-source projects, he improved test coverage for the Reflex-DOM FRP web library, highlighting a willingness to bridge functional programming tooling with pragmatic QA practices. Based in Phoenixville, PA, he combines production-grade engineering with a knack for untangling overengineered, decades-old codebases. Collected across finance, energy, and infrastructure, his experience favors performance, correctness, and incremental modernization.
17 years of coding experience
13 years of employment as a software developer
BA Computer Science, BA Computer Science at Cornell University
Stackoverflow
327reputation
42kreached
3answers
0questions
Github Skills (9)
functional-reactive-programming10
haskell10
testing10
frp9
reactive9
shebang6
smart-pointers6
python6
unique-ptr6
Programming languages (12)
Github contributions (5)
reflex-frp/reflex-dom
Jan 2020 - Feb 2020
Web applications without callbacks or side-effects. Reflex-DOM brings the power of functional reactive programming (FRP) to the web. Build HTML and other Document Object Model (DOM) data with a pure functional interface.
Role in this project:
QA Engineer / Test Automation Engineer
QA Engineer / Test Automation EngineerContributions:7 commits, 1 PR, 1 comment in 7 days
Contributions summary:Jimmy primarily contributed by adding and modifying test cases within the repository, specifically related to testing namespaces and general functionality. The commits demonstrate a focus on ensuring the correct processing of namespaces and other DOM-related features within the `reflex-dom-core` module. Their work improved test coverage and validated the core functionality of the Reflex-DOM library, which is used to build web applications. The user made several fixes and enhancements to the test suite.
callbacksfrpreactivepure-functionalhaskell
obsidiansystems/ledger-app-tezos
Apr 2018 - Jul 2020
Ledger app for Tezos
Contributions:9 releases, 335 commits, 14 PRs in 2 years 2 months
tezos-bakinghardware-walletbakingblockchainwallet
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