Developing the Python version of the ranking code took roughly 3 days. That includes writing the code, unit tests and documentation. Next, we’ve spent approximately 2 weeks optimizing the code. One of the optimizations was translating the score expression (simple_gauss(time)*popularity) into an abstract syntax tree. We also implemented caching logic which pre-computed the score for certain times in the future.
Go is an open source language, created at Google by Robert Griesemer, Rob Pike, and Ken Thompson. Open source here means that everybody can contribute to the language by opening proposals for new features, fix bugs etc. The language’s code is available on GitHub. Documentation on how you can contribute to the language is provided here.