See many previous discussions: Pros & Cons of using modules vs plain include? and Single module vs. submodules in a project and Large programs: structuring modules & include such that to increase performance and readability and What is the preferred way to use multiple files?
TLDR: Start with a single module in a single package, split into as many files as you want, and refactor as needed later on.
- Create at least one package for any major project, so that you can benefit from the Julia package system and the tooling around it.
- The most common pattern is a single module per package, but split up the implementation into as many files as you want, and just
includethem from the top-levelMyPackage.jlfile. (Each file is included once. It is no problem to call code from one file in another file of the same module.)- The reason to use submodules within a package is if you are running into namespace collisions from different parts of your implementation, but you can always introduce submodules later if this becomes an issue.
- Generally, split your project into multiple packages once you have functionality that could reasonably be used on its own. You can always do this later.
(Use Revise.jl during development, so that you can edit the package and execute the new code without having to re-load the whole package.)