[Haskell-cafe] Object-oriented programming, Haskell and existentials

[David Menendez]

On Wed, Oct 15, 2008 at 6:05 AM,  <oleg at okmij.org> wrote:
>
> Regarding existentials, the web page
>        http://okmij.org/ftp/Computation/Existentials.html
>
> demonstrates how to systematically eliminate existentials. In fact,
> the object encoding via existentials can be easily transformed into
> the encoding that uses only simple, first-order types. The web page
> begs a question if there is ever any real need for existentials.

We might justify existential types on performance grounds. Stream
fusion, for example, uses existentials to replace recursive types and
functions with non-recursive types and functions, which are simpler to
optimize.

-- 
Dave Menendez <dave at zednenem.com>
<http://www.eyrie.org/~zednenem/>