Add support to work with yarn workspaces

[matiasfha]

• I have searched the issues of this repository and believe that this is not a duplicate.
  But I think that this issue Add support for transpile packages installed via npm #3319 can be related and maybe solve the problem.

Current Behavior

Based on what I have:
I have a folder estructure working with yarn workspaces with multiple workspaces like:

|-- packages
|-- .babelrc
..
..
..
|----- shared
|-------- components // named @org/components
|-------- utils // named @org/utils
|----- web
|------- app // named @org/mainApp
|--------- src
|------------ next.config.js
|------------ .babelrc
|----------- pages
....
...
|------- otherPackage // named @org/otherPackage

Where app folder is a next.js app that import code from the other components.

The dev mode of next is run from root folder using npm run web that call next packages/web/app/src to allow next to found the pages folder (and next.config.js and .babelrc )

After run and start compiling, and get the "success" mensaje, some errors arise in the console on web loaded.
Errors referring to the use of type and import keywords in the files that comes from the imported modules (modules named as @org/ that lives inside the same repo but (maybe) in other workspaces).

This means that next webpack configuration is not transpiling the imported files. (the babel-plugin-transform-flow-strip-types is installed in packages/web/app and also in the root folder)

Expected Behavior

Should not have any error with the imported files and works as expected (no problem with es6 and flow).

Steps to Reproduce (for bugs)

1. Create a project with yarn workspaces activated
2. Create at least two workspaces
3. Create a package inside a workspace that run with next
4. Import file from other workspaces

Context

Your Environment

Tech	Version
next	4.2.3
node	9.3.0
OS	macosx
browser	safari/chrome
yarn	1.3.2

[bogdansoare]

Any news on this?

[beku8]

webpackDivMiddleware watch options are not working properly. This example is not picking up the changes from bar/ directory. Should we open a new issue?