Keno Fischer
Co Founder CTO (Tools) at JuliaHub
Boston, Massachusetts, United States
Summary
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Rockstar🎓
Top School
Top expert inScientific Computing and Data Science
Keno Fischer is a seasoned engineering leader and co-founder serving as CTO (Tools) at JuliaHub with 14 years of deep systems and language tooling experience. Based in Boston, he has driven core compiler and runtime work for the Julia language and contributed to high-profile open-source projects like JuliaLang/julia, IJulia (the Julia Jupyter kernel), and low-level tooling such as LLVM/Clang and rr. His strengths span compiler internals, automatic differentiation, cross-language interoperability (PyCall, PyJulia, Cxx.jl), and reproducible build systems (Yggdrasil/BinaryBuilder), reflecting a rare blend of research-grade rigor and production-focused engineering. Keno’s contributions often target subtle platform and interoperability edge cases—Windows and macOS compat fixes, syscall handling, and precompilation caching—helping large projects work reliably across environments. Trained in physics and mathematics at Harvard, he brings a principled, analytical approach to building developer tools that scale from notebooks to compilers.
14 years of coding experience
Master of Arts (AM), Physics, Master of Arts (AM), Physics at Harvard University
Stackoverflow
1,407reputation
57kreached
13answers
4questions
julia
top-5%
Github Skills (101)
interoperability10
python10
testing10
windows10
http10
c1110
c1710
gadfly10
pbuilder10
repr10
build-automation10
refactoring10
type-inference10
system-programming10
sparse-matrix10
Programming languages (31)
Github contributions (5)
JuliaInterop/Cxx.jl
Oct 2013 - Nov 2018
The Julia C++ Interface
Role in this project:
Back-end Developer
Back-end DeveloperContributions:3 releases, 390 commits, 65 PRs in 5 years 2 months
Contributions summary:Keno contributed to the Julia C++ Interface, by modifying the code to parse and use C++ types. The user's commits added functions to translate C++ types and expressions. They also modified the code to provide for exception handling and support for C++ array types and other features to make it function like a C++ REPL.
cppclangmagiccxxjulialang
JuliaLang/julia
Feb 2012 - Jan 2023
The Julia Programming Language
Role in this project:Back-end Developer
Back-end DeveloperContributions:1370 reviews, 2791 commits, 2726 PRs in 11 years 1 month
Contributions summary:Keno's contributions focused on the core implementation of the Julia programming language. They were involved in refactoring and improving key aspects of the compiler, specifically the SSA (Static Single Assignment) intermediate representation and the inlining infrastructure. The work involved modifying and enhancing the performance of core functions such as `sqrt`, `ldexp` and `getfield`. Furthermore, the user worked on improving the handling of data structures and optimizations related to functions and return types.
sciencejulia-languagemachine-learningjulialangpetsc
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