I try to contribute to open-source softwares both during my day job and my free-time.
As part of my work on Bazel, I created the Starlark language. It's a language derived from Python that can easily embedded in other tools.
Since Bazel adopted Starlark, the language has been used in many other places: at Google, at Facebook, at IBM, and in many other projects (e.g. the Delve debugger). Multiple implementations of Starlark exist.
On my free-time, I am still co-maintainer of the language specification.
I am an occasional contributor to VS Code. In particular, I have contributed to the design of the comments API, which can be used for integrating code review systems into VS Code.
I lead a team at Google that contributes to VS Code, as part of a collaboration with Microsoft.
Shader Minifier is an tool to obfuscate and minify shader code (GLSL or HLSL). It is able to do complex code (tree-based) transformations and clever variable renaming in order to make the code more compression-friendly.
It is now used by a large number of price-winning demoscene productions, especially 4kB intros.
I am responsible for 90% of Shader Minifier, I sometimes receive pull requests for other people.
I was part of the team at Google that open-sourced the Bazel build system. I constantly advocated inside Google for keeping the project as open as possible and encourage collaboration with the open-source users.
Bazel is now used by lots of companies, e.g. Adobe, Dropbox, Huawei, LinkedIn, Lyft, Nvidia, Pinterest, Uber, VMWare.
In 2010, I added support for the F# language in Emacs. As part of a contract position with Microsoft Research, I continued this work in 2011 and added a prototype of an Intellisense completion. I later transferred the ownership of the project and it was moved to GitHub.