David Ungar - Retired at Self

David Ungar

Retired at Self

Mountain View, California, United States

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Summary

🤩

Rockstar

🎓

Top School

David Ungar is a pioneering software researcher and engineer whose ideas underpin modern virtual machines and dynamic languages, including influential work that shaped Java and JavaScript runtimes and the Self language. With a career spanning Stanford, Sun, IBM, and Apple, he invented techniques such as dynamic optimization/deoptimization, generational GC ideas, and map-based storage that enabled high-performance, live-editable systems. A Dahl‑Nygaard and ACM Fellow honoree, he pairs deep research impact—four ACM-recognized papers—with hands-on engineering, from prototyping iOS apps to improving Swift’s compiler and debugger infrastructure. Even in retirement he continues to push language and tooling boundaries, recently contributing to swift-driver and swift-lldb for incremental compilation and debugging. Not obvious from titles alone, he also applied cartoon animation principles to UI design and built metacircular VMs and contextual programming prototypes, blending creativity with rigorous systems work.

15 years of coding experience

25 years of employment as a software developer

Ph.D., Computer Science, an ACM Outstanding dissertation, Ph.D., Computer Science, an ACM Outstanding dissertation at University of California, Berkeley

Diploma, Diploma at Albert Einstein Senior High School

Computer Science, Mathematics, Computer Science, Mathematics at Montgomery County Jr. College

MSEE&CS, BSEE, BSAMCS, Electrical Engineering, Computer Science, Applied Math, MSEE&CS, BSEE, BSAMCS, Electrical Engineering, Computer Science, Applied Math at Wasington University, St.Louis, MO

Github Skills (14)

swift10

compiler-design10

build-system10

incremental-compiler10

c-language10

cprogramming-language10

compile-time10

incremental-builds10

lldb10

compile10

build-automation9

automated-build9

irr9

debugging9

Programming languages (5)

C++CLLVMSwiftSelf

Github contributions (5)

swiftlang/swift-driver

Oct 2019 - Jan 2022

Swift compiler driver reimplementation in Swift

Role in this project:

Back-end Developer & Build/Release Engineer

Contributions:344 reviews, 549 commits, 303 PRs in 2 years 3 months

Contributions summary:David made several commits related to incremental compilation logic within the Swift driver, including the addition of new components and functionality for managing dependencies and build artifacts. The commits introduce new types for handling dependency information, along with methods for processing and integrating changes to ensure correct builds. The contributions focus on developing and enhancing the build process, specifically concerning incremental compilation, adding support for external module handling and improvements to ensure correctness.

driverswiftswift-compiler

apple/swift-lldb

Feb 2018 - Sep 2019

This is the version of LLDB that supports the Swift programming language & REPL.

Role in this project:

Back-end Developer

Contributions:16 commits, 14 PRs, 5 pushes in 1 year 8 months

Contributions summary:David primarily focused on enhancing the Swift LLDB debugger. Their contributions involved modifying the Swift expression parser and the Swift AST context to accommodate batch mode changes. This included passing `PrimarySpecificPaths` to key functions like `createEmptyModule` and `IRGenModule`. Further improvements included adding and renaming parameters in diagnostic handling functions.

lldbprogramming-languageswift

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