On 13 Mar 2009, at 14:32, Ross Paterson wrote:

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

Correspondingly, consider the functor Const Void.

Cheers

Conor

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