Rel: A Programming Language for Relational Data
Molham Aref, Paolo Guagliardo, George Kastrinis, Leonid O. Libkin, Victor Marsault, Wim Martens, Mary McGrath, Filip Murlak, Nathaniel Nystrom, Liat Peterfreund, Allison Rogers, Cristina Sirangelo, Domagoj Vrgoč, David Zhao, Abdul Zreika · 2025
Rel is a new relational language whose key design goal is to allow both database querying and programming in the large without relying on the currently dominant paradigm in which a query sublanguage is embedded in a host programming language. With the new approach we can model the semantics of entire enterprise applications relationally, which helps significantly reduce architecture complexity and avoid the well-known impedance mismatch problem. This paradigm shift is enabled by 50 years of database research, making it possible to revisit the sublanguage/host language paradigm, starting from the fundamental principles. We present the main features of Rel: those that give it the power to express traditional query language operations, and those that are designed to grow the language and allow programming in the large.