This blogpost explains and argues the claim that Ad-hoc polymorphism (Type-classes in Haskell/Scala/Purescript, Traits in Rust, Interfaces in Go/Java) makes code less type-safe.In other words: ad-hoc polymorphism makes it so that sometimes, after a refactor, code that is wrong and would not type-check without it, now still type-checks.
Plus the issue remains if the author replaced Vec with Vec of Vec instead of Option of Vec, or if iter().count() meant something completely different than “count # of iterated elements” (both pointed out in HN comments).
Plus the issue remains if the author replaced
VecwithVecofVecinstead ofOptionofVec, or ifiter().count()meant something completely different than “count # of iterated elements” (both pointed out in HN comments).