Re: [Haskell-cafe] New to Haskell

On Tue, 18 Dec 2007, Benja Fallenstein wrote:

Hi Henning,

On Dec 18, 2007 3:53 PM, Henning Thielemann 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.