Jack Pappas
Software Developer at Susquehanna International Group
Philadelphia, Pennsylvania, United States
Summary
👤
SeniorJack Pappas is a software developer with 15 years of experience focused on high-performance systems, working at Susquehanna International Group from 2013 to present. He specializes in .NET, C#, F#, numerical analysis, graph theory, compilers, GPGPU/CUDA, and distributed/parallel algorithms, with deep hands-on experience optimizing compiler internals and runtime code. His open-source contributions include performance and build-system improvements to the F# compiler and tooling, and testing and optimization work on the high-speed Blosc compression library and the Mono runtime, showing a strong emphasis on correctness, portability, and benchmarking. Jack combines low-level expertise (IL, pretty-naming, buffer safety) with practical build and test engineering, enabling robust HPC and developer-tooling workflows. Based in Philadelphia, he brings a rare mix of mathematical rigor and production-grade systems craftsmanship that surfaces in both compilers and high-throughput libraries.
15 years of coding experience
Stackoverflow
11,497reputation
230kreached
195answers
0questions
jit
top-5%
Github Skills (41)
build-script10
runtimes10
compiler-development10
testing10
dotnet-new10
dotnet10
c1110
c1710
compiler-compiler10
performance-optimization10
dotnet-core10
compiler10
compression10
fsharp10
functional-programming10
Programming languages (13)
Github contributions (5)
Blosc/c-blosc
Feb 2015 - Mar 2016
A blocking, shuffling and loss-less compression library that can be faster than `memcpy()`.
Role in this project:
Back-end & Test Automation Engineer
Back-end & Test Automation EngineerContributions:63 commits, 36 PRs, 39 comments in 1 year 1 month
Contributions summary:Jack primarily contributed to the testing and optimization of the Blosc compression library. Their work included fixing memory leaks, expanding test coverage to include larger data types, and improving test performance by switching to `memcmp` for round-trip data verification. Furthermore, the user implemented high-precision timing for the benchmark tool and addressed compiler-specific issues related to preprocessor macros. The user also implemented support for extensible fat-binary and x86-compatible feature-detection.
shufflingcompressionfastercompression-libraryblocking
fsharp/fsharp
Feb 2012 - Mar 2017
Please file issues or pull requests here: https://github.com/dotnet/fsharp
Role in this project:Back-end Developer
Back-end DeveloperContributions:37 commits, 2 PRs, 3 comments in 5 years 1 month
Contributions summary:Jack primarily contributed to the F# compiler's internal implementation. Their work involved modifying core modules such as `IL.fsi` (Abstract IL) and `PrettyNaming.fs`, suggesting involvement in code generation and compilation processes. They also optimized code in `filename.fs` and `EditDistance.fs`, indicating efforts to improve compiler performance. Additionally, they worked on build scripts and test suites, demonstrating experience with the build process and testing infrastructure.
dotnetfsharppull-requestscsharpdotnet-core
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