One little throwaway thing I learned was that Racket has named list extract methods for first, second, third, up to tenth. Perhaps that's not super-useful, but I wanted it in my Scala toolbox nonetheless.
So I implemented them in a Scala implicit class and put them on Github as well as here for your enjoyment:
It's just about the simplest possible implicit class implementation I can think of -- ten repetitive one-liners. Nonetheless, if you're having trouble structuring an implicit class, perhaps this helps you.
Also, I took the opportunity to try something new -- FunSuite from ScalaTest -- for unit testing. (Keep in mind that ScalaTest actually supports a few different unit testing styles. Here is a snippet of the test code: