vic / mill-buildr

An small Mill module that lets you define big project structures as a regular scala project itself.

Mill buildr module.

An small mill module that lets you define big project structures as a regular scala project itself.

Forget about large build.sc files or magic-importing lots of different .sc files, and use a normal .scala project you and your favorite IDE can understand and navigate easily.

Build History

Motivation

Splitting large build.sc files into different re-usable modules should be easy, and IDE navigation and code-completion should just work as with any other regular scala project.

One of the cool things about Mill is that its build definitions are loaded from ammonite-magic-infused build.sc file.

However when projects innevitably grow big you might find the need to split that huge build.sc of yours into smaller .sc files.

Perhaps some .sc files for shared settings (eg, versions/ivyDeps/mvnRepos, scalac-options, common tasks, reusable mill-modules) and maybe others for the many components that make your big project (eg, models, daos, service-ifaces, web-server, etc).

However some IDEs/editors have difficulties finding code references between .sc files and not providing code-completion can hurt developer experience specially for those who still need the IDE to help with completions and moving around files.

This tiny project was a hack we found thanks to ammonite magic imports that allowed us to split the build definition into a scala project on its own right. So that anyone who knows a little of scala can edit the project definition comfortably from their IDE.

Usage

All you need from this repo is a single file: BuildrModule.sc. You can either download it alongside your build.sc file. Or choose to import it directly from github - if doing so, please ensure to reference it on a particular commit -.

Then, define a buildr project where all your project modules will live as .scala files. And finally load the buildr runtime so you can define top-level objects in mill.

The following is annotated example, you might remove all comments once you are up and running.

// This is build.sc file.

// 1) If you downloaded `BuildrModule.sc` locally:
import $file.{BuildrModule => bm}

// 1) If loading from github, be sure to reference a commit instead of main branch:
// import $url.{`https://raw.githubusercontent.com/vic/mill-buildr/main/BuildrModule.sc` => bm}

// 2) Define a mill module as usual, in this example `buildr/src/*.scala`
object buildr extends bm.BuildrModule {
   // customize as any other ScalaModule, define custom coursierRepos, add ivyDeps, etc.
}

// 3) Finally compile and load your build definition into the mill runtime.
buildr.loadRuntime(build) // `build` here is the root-module since this file is named `build.sc`

@ // This ammonite marker is *very important* as it separate compilation units.

// All set. Now you can import your compiled mill-modules and
// (for this example see code at `buildr/src/buildr/ProjectOne.scala`)
import _root_.buildr.{ProjectOne, ProjectTwo, ProjectThree}

// That's it. All your `build.sc` file does is define the top level objects.
object one extends ProjectOne
object two extends ProjectTwo
object three extends ProjectThree

See the full example on this repository's build.sc file. Try running mill '__.{one,two}'