I found this difficult to follow since it requires you to learn Haskell, but luckily typeclasses.com is a paid service to learn Haskell.
[1] B. C. Oliveira, A. Moors, and M. Odersky. Type classes as objects and implicits. https://ropas.snu.ac.kr/~bruno/papers/TypeClasses.pdf
[2] O. Kieselyov, Implementing, and Understanding Type Classes. http://okmij.org/ftp/Computation/typeclass.html
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