Don Stewart
Software Engineer at Meta
Sydney, New South Wales, Australia
Summary
🤩
Rockstar🎓
Top SchoolDon Stewart is a seasoned software engineer and engineering leader with 23 years of experience building developer infra, trading systems, and dev tools across research, finance, and large-scale tech. He architects and implements high-performance systems with a functional-programming bias—expert in Haskell and experienced in Rust, C, PHP, and JavaScript—frequently contributing to foundational open-source projects like bytestring, vector, containers and Meta’s Glean. He has led teams up to 50 people, set org strategy, driven recruiting, and translated product priorities into reliable, low-latency services (including rewrites that reduced code-query latencies by orders of magnitude). Comfortable moving between IC and management roles, he blends hands-on optimization (C-level microbenchmarks, aarch64 ports) with cross-org partnership and clear technical comms. Based in Sydney but with a global career footprint, he pairs deep systems expertise with a knack for building communities and shipping tools engineers enjoy using. An unconventional detail: he began life on a farm in Australia and has repeatedly ported compilers and core libraries to niche architectures, reflecting both practical grit and systems-level curiosity.
23 years of coding experience
20 years of employment as a software developer
UNSW Sydney
Stackoverflow
137,644reputation
4.6mreached
1,098answers
4questions
package
top-5%
ocaml
top-5%
floating-point
top-5%
debugging
top-5%
naming-conventions
top-5%
dictionary
top-5%
Github Skills (110)
programming-language10
benchmark10
package-management10
multithreading10
quickcheck10
compiler-construction10
profiling10
hashtable10
coding-style10
haskell10
concurrency10
optimization10
garbage-collection10
polymorphism10
parallel-processing10
Programming languages (9)
Github contributions (5)
facebookincubator/Glean
Apr 2021 - Jan 2023
System for collecting, deriving and working with facts about source code.
Role in this project:
Back-end Developer
Back-end DeveloperContributions:40 reviews, 392 commits, 239 PRs in 1 year 8 months
Contributions summary:Don optimized data fetching for specific facts in the Glean system, resulting in significant performance improvements (up to 10x faster). They refactored data fetching and implemented support for building Glean on aarch64 architecture. In addition, they added new functions in Haskell and code for handling various types. They also made a large number of build fixes in addition to a new LSIF indexer.
collectingderivingfacts
haskell/bytestring
Aug 2005 - Jan 2009
An efficient compact, immutable byte string type (both strict and lazy) suitable for binary or 8-bit character data.
Role in this project:Back-end Developer
Back-end DeveloperContributions:722 commits in 3 years 5 months
Contributions summary:Don made several contributions to the Haskell bytestring library. They primarily focused on refactoring and enhancing the performance of core functions. The user implemented new functions, such as `sortPS` and `findIndicesPS`, and re-implemented existing ones like `comparePS`, `filter`, and `reversePS` using optimized C-based memory operations. Their contributions included optimizations and improvements to existing functionality, resulting in significant space and time gains.
byte-string8-bitbytecompactstring
Find and Hire Top DevelopersWe’ve analyzed the programming source code of over 60 million software developers on GitHub and scored them by 50,000 skills. Sign-up on Prog,AI to search for software developers.