Online Historical Encyclopaedia of Programming Languages

The Online Historical Encyclopaedia of Programming Languages (HOPL) is a comprehensive database documenting 8,945 programming languages from the 18th century to present day, including 7,800 influence links and over 11,000 citations. The resource provides genealogical trees, advanced search capabilities, and analysis of language taxonomy and evolution. The project has been maintained since 1995 by Diarmuid Pigott with contributions from other librarians and curators.