Joseph Groff
Senior Swift Compiler Engineer at Apple
San Jose, California, United States
Summary
🤩
Rockstar🎓
Top SchoolJoseph Groff is a Senior Swift Compiler Engineer with 18 years of systems and language-implementation experience, currently shaping Swift at Apple from San Jose. He co-designed Swift's SIL and implemented core compiler and runtime features—bridging Swift and Objective-C, optimizing ARC, generics, and debugging support in projects like swift, swift-clang, and swift-lldb. Comfortable in C, C++, Objective-C and Swift, he brings deep CPU and OS architecture knowledge across x86, ARM, and ARM64, plus a long history of LLVM work and low-level memory and toolchain fixes. His open-source contributions span high-impact Apple repos and niche language projects like Factor, where he implemented row polymorphism and profiling support. Pragmatic, diplomatic, and ego-free, he is known for turning research-quality language ideas into production-ready compiler infrastructure.
18 years of coding experience
7 years of employment as a software developer
Associate’s Degree, Associate’s Degree at College of the Redwoods
Github Skills (28)
debugging10
objective-c10
debug10
strings10
foundation10
text-manipulation10
foundation-sites10
lldb10
attribute10
compiler-design10
intermediate-language10
factor10
swift10
c-language9
sem9
Programming languages (14)
Github contributions (5)
factor/factor
May 2009 - Mar 2012
Factor programming language
Role in this project:
Back-end Developer
Back-end DeveloperContributions:2733 commits, 6 comments in 2 years 11 months
Contributions summary:Joseph's commits primarily focused on implementing row polymorphism in the Factor programming language's stack checker. Their work involved modifying the stack checker's internal logic and data structures to support polymorphic stack effects, particularly in the context of inline combinators. The user added functionality to declare and handle polymorphic input quotation effects, enabling more robust type checking for combinators with variable stack effects. The user also refactored existing functionality to account for the addition of said polymorphism.
script-enginecompilerprogramming-languagecompiledapl
swiftlang/swift-corelibs-foundation
Feb 2013 - May 2019
The Foundation Project, providing core utilities, internationalization, and OS independence
Role in this project:Back-end Developer
Back-end DeveloperContributions:54 commits, 1 PR, 2 pushes in 6 years 4 months
Contributions summary:Joseph primarily contributed to the Swift Foundation library, focusing on core functionality and bridging between Swift and Objective-C. Their work included optimizing string conversion, implementing bridging shims, and refactoring memory allocation. They also addressed issues related to NSError bridging and improved the handling of Objective-C objects within the Swift runtime, including some low-level memory management.
tvostranslationinternationalizationfoundationindependence
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