[Haskell-beginners] Heterogeneous Lists

[Ozgur Akgun]

Hi.

On 28 May 2013 18:07, Frerich Raabe <raabe at froglogic.com> wrote:

>
> On May 28, 2013, at 12:36 AM, harry <voldermort at hotmail.com> wrote:
>
> > Every OO language which supports generics allows a declaration such as
> > List<Show> alist, where Show is an interface. Any type implementing Show
> can
> > be put in alist, and any Show operation can be performed on the alist's
> > members. No casts, wrappers, or other special types and plumbing are
> needed.
> >
> > Why isn't it possible to do this directly in Haskell?
>
> My impression is that you often don't have this requirement, since
> functions are first-class values and you can treat them as closures.
>

This might also be relevant:
http://okmij.org/ftp/Computation/Existentials.html

Hope this helps,
Ozgur.
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