How to combine the Module Dependencies with the Dependencies of its parent Module with Mill

Question

I want to combine the Module Dependencies with the ones from the parent Module.

I have the following in my build.sc:

  trait ExampleModule extends ModuleWithTests {
    override def moduleDeps = Seq(camunda, cli)
  }    
  object twitter extends ExampleModule {
    override def moduleDeps = super.moduleDeps ++ Seq(twitterApi)
  }

This gives me:

build.sc:222: type mismatch;
 found   : Seq[build.this.ModuleWithTests]
 required: Seq[build.this.ModuleWithTests{def moduleDeps: Seq[build.this.ModuleWithTests]}]
    override def moduleDeps = super.moduleDeps ++ Seq(twitterApi)
                                               ^
build.sc:222: `T.command` definitions must have 1 parameter list
    override def moduleDeps = super.moduleDeps ++ Seq(twitterApi)
                 ^
Compilation Failed

Is there a way to achieve this, or do I have to list the module dependencies in each child module?

score 1 · Accepted Answer · answered May 02 '20 at 10:03

Your example is almost right, but because you omitted the explicit return type of ExampleModule.moduleDeps it seems the compiler inferred a more specific type of Seq[ModuleWithTests] in this case. Looks like all your modules camunda and cli also implement this trait. Whereas twitterApi seems to not implement it.

To fix the compile error, you might try to add the explicit return type Seq[JavaModule] to ExampleModule.moduleDeps.

How to combine the Module Dependencies with the Dependencies of its parent Module with Mill

1 Answers1