Hack Codegen is a library for easily generating Hack code and writing it into signed files that prevent undesired modifications. The idea behind writing code that writes code is to raise the level of abstraction and reduce coupling. You can use your own way of describing a problem and generate the corresponding code. E.g. see examples/dorm. In this example, we use a schema to describe the structure of the data, and we use Hack Codegen to write the matching code.