A software language repository (SLR) is a software repository for software languages: definitions, implementations, language processors, and sample artifacts. YAS (Yet Another SLR) is an SLR
targeting teaching and research on the foundations and engineering of software languages; it uses Haskell, Prolog, Java, and Python for implementing language processing functionality; YAS also exercises various other technologies for language processing, e.g., the ANTLR parser generator and the StringTemplate library for template processing. YAS is the codebase underlying the introductory textbook on software languages by this author. YAS relies on a megamodeling approach for build management and regression testing.