ScalaQL: Language-Integrated Database Queries for Scala

Daniel Spiewak, Tian Zhao. ScalaQL: Language-Integrated Database Queries for Scala. In Mark G. J. van den Brand, Dragan Gasevic, Jeffrey G. Gray, editors, Software Language Engineering, Second International Conference, SLE 2009, Denver, CO, USA, October 5-6, 2009, Revised Selected Papers. Lecture Notes in Computer Science, Springer, 2009.


One of the most ubiquitous elements of modern computing is the relational database. Very few modern applications are created without some sort of database backend. Unfortunately, relational database concepts are fundamentally very different from those used in general-purpose programming languages. This creates an impedance mismatch between the the application and the database layers. One solution to this problem which has been gaining traction in the .NET family of languages is Language-Integrated Queries (LINQ). That is, the embedding of database queries within application code in a way that is statically checked and type safe. Unfortunately, certain language changes or core design elements were necessary to make this embedding possible. We present a framework which implements this concept of type safe embedded queries in Scala without any modifications to the language itself. The entire framework is implemented by leveraging existing language features (particularly for-comprehensions).