HASSL is a compiler for the Home Assistant Simple Scripting Language (DSL) that transforms .hassl files into Home Assistant automation packages. The system parses HASSL syntax using Lark, resolves imports and packages, performs semantic analysis to build an intermediate representation, and generates YAML output including helpers, scripts, sync automations, rule automations, and schedule sensors. Key features include loop-safe context tracking, per-rule enable gates, template-based code reuse, and comprehensive schedule support with window syntax and holiday integration. The architecture is modular with distinct phases: parsing, transformation, analysis, and code generation, each handled in separate modules. The CLI orchestrates the process, handles dependency loading of imported files, and writes output to a directory structure suitable for Home Assistant's packages folder.