Why is Haskell missing “obvious” Typeclasses

Question

Consider the Object-Oriented Languages:

Most people coming from an object-oriented programming background, are familiar with the common and intuitiv

Answer 1

Such typeclasses exist in standard Haskell, but they don't have the same name as their equivalent OO counterparts. The Collection typeclass, for example, is called Foldable in Haskell. You can use it to test if a structure is empty (foldr (const False) True x) or to count the number of elements (foldMap (const 1) x), or to test for set membership (foldr (\e' present -> (e==e') || present) False x for some e).

For operations like element lookup, you have the Array typeclass which might work for sequential data. For more flexibility, you can write your own Indexable class, like this for example (beware of lenses) :

class Indexable m k a where
  at :: k -> Lens' m (Maybe a)

The null element and set union belong to the Monoid typeclass (where mappend == union). In this light, set difference could also be implemented in its own typeclass Differentiable (which I'm sure already exists in dozens of Haskell libraries) and we would have total compatibility with imperative languages.

Haskell, by virtue of being designed by mathematicians and the like, doesn't employ the same vocabulary as most other languages, but rest assured, it doesn't mean that it's not a practical language in addition to being an awesome one :-)