The beginner isn't defining the instances. But the experts want the flexibility to define such instances, and that means even beginner code can involve an unhel

The beginner isn't defining the instances. But the experts want the flexibility to define such instances, and that means even beginner code can involve an unhelpful amount of polymorphism. This isn't the case in Rust, where literals are near enough monomorphic. There's a similar situation with the now classic: Prelude> length ['a','b'] 2 Prelude> length ('a','b') 1 Here, beginners are potentially being burned by the fact that "length" is polymorphic with the type: length :: Foldable f => f a -> Int which is not a type I want to explain to beginners. At the same time, as an expert, I want length to be polymorphic and don't want to sacrifice its polymorphism for the sake of beginners.