Patrick Lannigan
Staff Software Engineer at Horizon3.ai
Medford, Massachusetts, United States
Summary
👤
Senior🎓
Top SchoolPatrick Lannigan is a staff software engineer with over a decade of experience architecting developer-facing platforms and refactoring complex legacy systems to be maintainable, secure, and testable. He’s led company-wide initiatives at Wayfair and Stavvy to standardize project templates, automate migrations, and teach engineering best practices, enabling thousands of engineers to move faster. Comfortable across languages and domains—from Python platform tooling and Dockerfile grammars to C/C#/Java components—he’s also contributed to notable open-source projects like the Lark parser and the Klaxon JSON parser, improving type safety and parsing robustness. Known for combining hands-on refactoring with metrics-driven planning, he surfaces high-impact features by collaborating closely with stakeholders and end users. Based in Medford, MA, he mentors engineers and drives pragmatic, auditable solutions that reduce operational toil while improving developer experience.
10 years of coding experience
18 years of employment as a software developer
Master of Science - MS, Computer Science, Master of Science - MS, Computer Science at Northeastern University
English
Github Skills (16)
grammar10
kotlin10
parsec10
parserator10
json10
typehinting10
grammars10
parser10
type-checking10
exception-handling10
parsing10
par10
python10
parse10
testing10
Programming languages (10)
Github contributions (5)
lark-parser/lark
Aug 2021 - Feb 2022
Lark is a parsing toolkit for Python, built with a focus on ergonomics, performance and modularity.
Role in this project:
Back-end Developer
Back-end DeveloperContributions:21 reviews, 22 commits, 12 PRs in 5 months
Contributions summary:Patrick primarily focused on improving the type annotations and code structure of the Lark parser. They made several commits to improve the type hinting of classes like `Transformer`, `TransformerChain`, and `Interpreter`, increasing code reliability. Additionally, the user refactored parts of the code, changing internal annotations and removing redundant generic typing of `Any` and other simplifications to improve maintainability. They also made modifications to the tree template system.
parsing-libraryearleypythonparsersmodularity
cbeust/klaxon
May 2018 - Jun 2018
A JSON parser for Kotlin
Role in this project:Back-end Developer
Back-end DeveloperContributions:7 commits, 4 PRs, 5 comments in 9 days
Contributions summary:Patrick primarily focused on improving the Klaxon JSON parser for Kotlin. They refactored the exception handling, replacing `RuntimeException` with `KlaxonException` and introducing `JsonParsingException` for more specific error scenarios. Their work included modifying the parsing logic to correctly handle different data types like strings, integers, doubles, booleans, longs and big integers. The user also implemented comprehensive unit tests, including data providers, to validate these changes and ensure correct parsing behavior, including error handling for invalid inputs.
parserkotlinjsonjson-parser
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