Karoy Lorentey
Swift Standard Library Engineer at Apple
San Francisco Bay Area United States
Summary
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Rockstar🎓
Top SchoolKaroy Lorentey is a Swift Standard Library Engineer with 19 years of systems and language-level engineering experience, currently based in the San Francisco Bay Area. At Apple he contributes to the Swift standard library and debugger (LLDB), focusing on string performance, UTF-16/bridging optimizations, and better developer diagnostics. He’s also a prolific open-source author of high-performance data structures (e.g., BTree) and the author of "Optimizing Collections in Swift," blending practical benchmarking with algorithmic rigor. Prior roles include principal engineering and cross-platform client work at LogMeIn and years of systems and academic teaching experience, giving him a rare mix of low-level systems, tooling, and product-facing UI knowledge. Known for meticulous test and benchmark work, he often surfaces non-obvious performance wins by rethinking core abstractions.
19 years of coding experience
16 years of employment as a software developer
MSc Computer Science, MSc Computer Science at Eötvös Loránd University
English, Hungarian
Stackoverflow
4,873reputation
196kreached
34answers
2questions
xcode
top-5%
security
top-5%
macos
top-5%
debugging
top-1%
iphone
top-5%
objective-c
top-5%
Github Skills (36)
algorithm10
debugging10
objective-c10
algorithms10
filesystem10
posixct10
system-programming10
utf10
testing10
text-manipulation10
file-operations10
lldb10
data-structure10
xctest10
performance-optimization10
Programming languages (9)
Github contributions (5)
attaswift/BTree
Dec 2015 - May 2018
Fast sorted collections for Swift using in-memory B-trees
Role in this project:
Back-end Developer & Algorithm Engineer
Back-end Developer & Algorithm EngineerContributions:12 releases, 501 commits, 9 PRs in 2 years 5 months
Contributions summary:Karoy contributed to the implementation of B-tree data structures, including core node operations and internal algorithms. These include the creation of a b-tree implementation and subsequent additions for key insertion, removal, and subtree operations. Further changes involved refactoring for data structure correctness and code readability, like renaming types and standardizing methods. The user also appears to have focused on a performance-focused design approach, with modifications in the project's structure and use of specialized types.
btreeswiftorderedcollectionsearch-trees
apple/swift-system
Feb 2021 - Jan 2023
Low-level system calls and types for Swift
Role in this project:Back-end Developer
Back-end DeveloperContributions:116 reviews, 29 commits, 45 PRs in 1 year 11 months
Contributions summary:Karoy primarily contributed to the low-level system calls and types for Swift. Their work included adding symbolic names for standard file descriptors and implementing support for `dup` and `dup2`. The user also unified availability annotations and added a script to manage them. These changes involved modifying core system files and tests.
swiftsystem-callsfile-pathfile-descriptorposix
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