No More Orphans
This is a sample project that defines a couple optional typeclass instances using No More Orphans trick. More details are in the accompanying blog post.
Use SBT to run the test suite:
git clone https://github.com/7mind/no-more-orphans.git cd no-more-orphans sbt test
Tested on Scala 2.12.8, 2.13.0-M5, 2.11.8 and dotty-0.16.0-RC3