[Haskell-beginners] why is there no typeclass common to all containers?

Jeffrey Brown jeffbrown.the at gmail.com
Tue May 31 22:57:04 UTC 2016

In Haskell typeclasses are based on what you want to do with something. If,
for instance, you want to be able to map over a container, you can make it
an instance of class Functor -- which all the standard containers (List,
Map, Set, Tree, Maybe ...) already are.

On Tue, May 31, 2016 at 3:26 PM, Silent Leaf <silent.leaf0 at gmail.com> wrote:

> In fact it all comes down to trying to add partially a feature absent from
> the Haskell language, which is the ability to distinguish values both on
> name *and* on type --thus allowing two variables of the same name if they
> have different types.
> Honestly i don't see the drawback of that name system, but i guess there
> must be one otherwise it'd have been chosen by default instead of the
> typeblind current name system.
> Le mercredi 1 juin 2016, Silent Leaf <silent.leaf0 at gmail.com> a écrit :
> > All in the title. I haven't used them much, but I saw Map or Vector
> types were forcing the user to use qualified functions unless you want
> nameclash with the more basic, typically list-oriented functions.
> > So, why not have a massive, general purpose interface so the type only
> can separate between containers --which would allow for cross-container
> polymorphism, i suppose, more easily, even though it's not necessarily the
> most widespread need.
> > So, do i miss something? Is there in fact a class of that kind? If so
> why not?
> > Thanks in advance! :)
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Jeffrey Benjamin Brown
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