It's not necessarily 1:1 file:module.

`#lang foo ....` in name.rkt is (in part) a shorthand for `(module name foo ....)`.

A single Racket file can have 1 or more modules.

Each module can also have sub-modules.

Modules generalize runtime vs. compile-time to many kinds of time, including but not limited to "test time", "doc time", etc. Also they enable reproducible compiles by clarifying what "compile-time" actually means relative to other modules. It's more than "paste these s-expressions at the top-level prompt and auto-prefix some names."

Racket has a wonderful module system and sometimes I miss that in Clojure, although I enjoy Clojure very much in other respects.