Re: [Haskell-cafe] Are newtypes optimised and how much?

On 10/20/10 4:09 AM, Simon Peyton-Jones wrote:

No, this isn't optimised. The trouble is that you write (map Foo xs), but GHC doesn't know about 'map'. We could add a special case for map, but then you'd soon want (mapTree Foo my_tree).

How about a special case for fmap? That seems like it should handle a lot of cases. Cheers, Greg