Sam Halliday
Summary
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RockstarSam Halliday is a Senior Principal Engineer with 18 years’ experience building elegant, high-performance systems and improving existing platforms for clients including Disney, Morgan Stanley, the European Space Agency and the UK MoD. With a PhD in Mathematical Physics and deep roots in open source, he contributes to cornerstone Scala projects such as ZIO, shapeless and scalaz, driving type-safe, concurrent and generic programming improvements. He excels at simplifying technically challenging, cross-disciplinary problems into robust, efficient solutions that scale in production. A founder and serial contributor, Sam blends research-grade rigor with pragmatic engineering—often focusing on performance, correctness and maintainability in core libraries that other engineers rely on.
18 years of coding experience
Github Skills (40)
algorithm10
json10
algorithms10
typesc10
typeclass10
refinement-types10
encoder10
projectile10
scalaz10
generic-derivation10
zio10
decode10
data-structure10
emacs-lisp10
scala10
Programming languages (35)
Github contributions (5)
zio/zio-json
Jul 2020 - Jan 2022
Fast, secure JSON library with tight ZIO integration.
Role in this project:
Back-end Developer
Back-end DeveloperContributions:5 reviews, 9 commits, 6 PRs in 1 year 6 months
Contributions summary:Sam primarily contributed to the `zio-json` library by implementing core features and addressing bugs related to encoding and decoding JSON data. Their work involved modifying the `Encoder` and `Decoder` traits and related implementations, particularly concerning the handling of data structures such as `Either`, `Option`, and collections. The user's commits also added support for new features and compatibility with other libraries, as evidenced by the addition of Scalaz and Refined integrations. Furthermore, the changes reflect improvements in code structure and internal utilities for JSON processing.
zioscalajsonperformancesecurity
softwaremill/magnolia
Nov 2017 - Aug 2018
Easy, fast, transparent generic derivation of typeclass instances
Role in this project:Backend Developer
Backend DeveloperContributions:18 commits, 8 PRs, 42 comments in 8 months
Contributions summary:Sam primarily contributed to the `magnolia` library, focusing on generic derivation of typeclass instances. Their work included adding an alpha release, implementing benchmarks for scalaz-deriving, and refactoring code for `econstruct` functionality. Furthermore, they addressed issues related to default value construction and auto-derivation within the codebase, enhancing the library's usability and functionality. These changes involved core library code and test cases.
generic-derivationtypeclassgeneric-programmingscalatypeclass-derivation
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