Starlark

Starlark is a programming language that was purpose-built for built systems. The embeddable rust starlark implementation that is also used in buck2 has a couple of very strong points:

• Nice API to lazily load/execute modules.
• Fast.
• Types.
• Clear impact on changed files. (no mutable global state)
• Language server integration.

Compared to a non-programmable config language, it allows us more flexible runtime configuration with less boilerplate.