[Haskell-cafe] New to Haskell

Henning Thielemann lemming at henning-thielemann.de
Tue Dec 18 11:17:00 EST 2007

On Tue, 18 Dec 2007, Benja Fallenstein wrote:

> Hi Henning,
> On Dec 18, 2007 3:53 PM, Henning Thielemann
> <lemming at henning-thielemann.de> wrote:
> > Since this was discussed already here, I summed it up in:
> >   http://www.haskell.org/haskellwiki/Show_instance_for_functions
> I find the discussion under "theoretical answer" unsatisfying. The
> property that a Show instance for functions would break is
> extensionality, and while extensionality is a desirable trait and
> matches the common mathematical intuitions, a system with intensional
> functions certainly isn't "unmathematical" or impure.

The mathematical definition of "function" I know of, says that functions
are special relations, and relations are sets of pairs. Their is nothing
about intension.

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