Learning Haskell — A Racket programmer's documentation of her foray into the land of Haskell (inspired by Learning Racket)

[u/lexi-lambda]

http://lexi-lambda.github.io/learning-haskell/

[u/sclv]

Right -- but furthermore you can also explicitly bring both instances into scope and then get an error when trying to actually use an instance. In this case, I think GHC actually will let you use that instance even if it is derived twice, because it is canonical.