17.4 Interactive Module Loading
If invoking module-path requires loading any files, then modification dates of the files are recorded. If the file is modified, then a later enter! re-loads the module from source; see also Module Re-declarations. Similarly if a later enter! transitively requires a modified module, then the required module is re-loaded. Re-loading support works only for modules that are first loaded (either directly or indirectly through transitive requires) via enter!.
After switching namespaces to the designated module, enter! automatically requires racket/enter into the namespace, so that enter! can be used to switch namespaces again.
When enter! loads or re-loads a module from a file, it can print a message to (current-error-port), as determined by the optional noise-flag. It can be #:verbose to print a message about such loads and re-loads, #:verbose-reload to print a message only for re-loaded modules, and it can be #:quiet for no printouts.