> "Any sufficiently large test suite will contain an ad-hoc, informally-specified, bug-ridden, slow implementation of half of the Haskell type system" -- Smith's Law
http://lucacardelli.name/Papers/OnUnderstanding.A4.pdf
See Section 1.3 "Kinds of Polymorphism" (there is a typo in the paper and section 1.4 is mislabeled as "1.3" as well.)
> "Any sufficiently large test suite will contain an ad-hoc, informally-specified, bug-ridden, slow implementation of half of the Haskell type system" -- Smith's Law