Curated Picks

A February 2025 Hacker News discussion on The Simplicity of Prolog generated over 120 comments debating the language's limitations and modern viability. Long-time practitioners criticized Prolog's abstraction features, first-class predicate support, and search strategy control, while advocates highlighted elegant problem expression with Constraint Logic Programming (CLP). The discussion revealed a technical schism between SWI-Prolog's "batteries-included" approach (which introduced a non-standard dict syntax breaking backward compatibility) and Scryer Prolog's ISO-focused purity. Commenters cited concrete applications including a GNU Prolog-based Void Linux installer, TerminusDB's codebase, and use in cancer research and government funding models.

A July 2024 Hacker News thread asking "What's Prolog like in 2024?" generated over 250 comments debating its modern relevance. Practitioners highlighted Scryer Prolog's strict ISO conformance and 24x memory efficiency for string processing, and Trealla Prolog's embeddability via WebAssembly. Integration with mainstream ecosystems was a key theme, evidenced by the Janus library for Python-Prolog interop and Datalog's use as a more expressive recursive query layer than SQL. Critics pointed to persistent challenges: fragmented implementations, the difficulty of controlling backtracking in large systems, and a lack of standardized tooling. Multiple comments noted Prolog's enduring commercial niche in complex product configuration (CPQ) and scheduling engines, where constraint logic programming remains a competitive advantage.

A September 2023 Hacker News discussion on The Power of Prolog garnered over 100 comments, with practitioners describing the language as a "mind bending" paradigm shift for constraint solving and symbolic AI. Multiple users cited challenges integrating Prolog into modern software stacks and deprecated its use in systems like Gerrit's submit rules due to maintainer unfamiliarity. The dialogue highlighted concrete use cases, including TerminusDB's core implementation and historical application in Windows NT network configuration. Commenters noted a growing interest in purely logical dialects like Datalog for static analysis, while debates centered on the language's suitability for production versus its role in expanding problem-solving approaches.

Microsoft embedded the Small Prolog interpreter within Windows NT's network configuration subsystem (NCPA.CPL) to declaratively solve the "plumbing" problem of binding interdependent drivers and protocols. According to the paper, components were abstracted as objects with interface classes; Prolog facts and rules then determined all valid bindings and load orders via backtracking. This centralized, declarative approach reportedly simplified installation, prevented invalid configurations, and allowed vendors to add components via declarative scripts rather than procedural code. Microsoft stated the system contributed to Windows NT Advanced Server being judged as particularly reliable and simple to configure.