4 Organizing Racket Code

Functional languages, such as Racket, often give you more freedom in organizing your code base than you might be used to, but this freedom can make it hard to know how to keep your code base orderly. Languages like Java force a correspondence between classes and files, almost forcing you to organize your code. Racket doesn’t care about how functions are organized into files. While you can put all your code in a single file, this makes browsing the code hard, complicates version control and merge conflicts, defeats separate compilation, and just feels gross.

Typically, a Racket program organizes groups of functions that are conceptually related into a file. We might gather all functions related to register allocation into a single file. But maybe that file is too big (a subjective experience, not a clear dividing line), so we divide further: all functions related to conflict analysis in one file, all functions related to undead analysis in another. Often, we have a few functions that are needed in various placed, but don’t fit in any conceptual group. It’s common to stick these functions in a miscellaneous file, perhaps named utils.rkt.

We can emulate anything we would do with files by using module. The below examples demonstrate organizing code into separate modules, which we could store in separate files.

Tests are not commonly placed in-line with code, the way you were taught in 110, but split out in to separate files. The Racket testing framework can automatically scan all files for (module+ test ...) and run the test suites it finds. It’s common to split tests into conceptually related files, too. For example, I might group all tests related to register allocation into one file, and tests that check the interpreter against the compiler into another.

It’s common to put all the test files in a separate test directory.

Of course, your assignments dictates that there be a particular file that exports particular names; thankfully, Racket’s module system allows reproviding definitions you’ve imported from elsewhere. For example, Assignment 3 requires there be a file called a3.rkt in which you define certain functions.

4.1 Organizing your code to keep your graders sane

The above is a stylistic discussion about Racket best practices, some of which applies to other functional languages. However, you’re also students, and we have to grade your code.