Yacc grammar for a custom query language that supports filtering, sorting, and faceted search over in-memory datasets. The parser produces an AST that is optimized and evaluated at runtime. The repository includes a code generator (ql/generator) that reads Go struct definitions and auto-generates dataset accessor code, making it a reusable pattern for adding query capabilities to any Go struct slice.

A circular buffer-based rolling counter that tracks integer increments over configurable time windows. It supports efficient sliding window calculations with automatic interval clearing, binary serialization for persistence, and is used to monitor proxy offer/success rates within short (5-minute) and long (24-hour) windows. The implementation is self-contained and can be extracted into any project that needs lightweight time-series aggregation.

A configurable HTTP proxy checker that verifies proxy liveliness and anonymity by fetching a known IP-check page and comparing the returned IP. Supports multiple strategies: 'simple' (randomly picks one of several external IP checkers), 'headers' (looks for real IP in response headers indicative of transparent proxies), and 'twopass' (combines both). The checker is designed as an interface and can be reused in other projects needing proxy validation.