Catlang: A New Programming Language Compiles to a Single SQL SELECT Statement

Introduction to Catlang

Catlang is a newly developed programming language designed to compile directly into a single SQL SELECT statement. When this generated SQL query is executed in a PostgreSQL database, it produces the output of the original Catlang program. This approach differs from traditional query languages by treating SQL as a compilation target for a full programming language.

Motivation and Core Features

The primary motivation behind Catlang was to create a unique compilation target to test its core feature: an intermediary language built upon abstract category theory concepts. The language's syntax incorporates elements reminiscent of arrow notation, allowing for constructs such as loops and conditional logic within the program that are then translated into the SQL output.

Example: A Looping Function

An example function named 'count' demonstrates Catlang's capabilities. This function, which always returns 100 regardless of input, implements its logic using a loop construct. The loop iteratively modifies a variable 'n' until it reaches 100, showcasing how control flow is expressed in Catlang before its transformation into SQL.

Intermediary Language and Compilation

After desugaring the source code, Catlang programs are converted into an intermediary representation based on category theory. This abstract representation is then used to generate the final SQL SELECT statement. The compiler also includes an arrow desugarer, which processes the arrow-like syntax used in Catlang's source code.