Buck: How we build Android apps at Facebook

Introduced Buck, a new build system for Android, to address slow build times and complexity associated with Ant and Android library projects. Buck favors the creation of many small modules, leading to fine-grained dependencies and significantly faster build times (from 3m40s to 1m30s). It also simplifies code reuse across multiple Android apps built from a single codebase and enables faster iteration by allowing quick building of small sample applications.