The first line sounds like hubris, but amazingly it's actually true. QuickCheck makes extremely good (not over-complex or 'clever') use of return type polymorph

The first line sounds like hubris, but amazingly it's actually true. QuickCheck makes extremely good (not over-complex or 'clever') use of return type polymorphism and applicatives. Property testing is a good idea in any language, but its particularly elegant in Haskell.