Stanisław Barzowski of XTX Markets and a committer on the jsonnet project joins SE Radio's Robert Blumen for a conversation about the jsonnet programming language. A superset of JSON, jsonnet adds programming language capabilities, particularly to address the need to handle large but mostly repetitive JSON configurations. They discuss the project's history, use cases for Grafana and Kubernetes config, and interoperability with YAML. They examine jsonnet details, including the command line, constrained capabilities of the language, and objects and inheritance, and then consider the toolchain: compiler, formatter, and linter, as well as test frameworks and testing, package management, and the language's performance. Barzowski describes four implementations -- go, C++, Rust, and Scala -- as well as popular libraries and the standard library.