Re: [Haskell-cafe] Pointless functors

For most functors, that is equivalent to point x = undefined But by that logic, everything is a member of every typeclass... -- Robin On Fri, 13 Mar 2009 17:35:31 +0300 Eugene Kirpichov wrote:

'An arbitrary element' means 'undefined will suffice'

point x = fmap (const x) undefined

2009/3/13 Ross Paterson :

...

On Fri, Mar 13, 2009 at 03:18:15PM +0100, Martijn van Steenbergen wrote:

...

Are there any functors f for which no point/pure/return :: a -> f a exists?

No.  Choose an arbitrary element shape :: f () and define

       point x = fmap (const x) shape _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe