Hakana: Taking Hack Seriously

This post introduces Hakana, a new open-source static analysis tool for Hack, developed at Slack. It details Hakana's technical foundation (based on Psalm, written in Rust, using Hack parser), its usage in CI for code behavior enforcement (unused code, type checks, security vulnerabilities, internal API misuse), its security analysis capabilities (interprocedural and intraprocedural analysis, literal string types for SQL injection prevention), its extensibility via plugins, and its performance benefits (5x faster than Psalm). It also explains the rationale for open-sourcing Hakana.