Re: [Haskell-cafe] Functor and Haskell

Daryoush Mehrtash-2 wrote:

...

singleton :: a -> [a] singleton x = [x]

Here F is the identity functor, and G is the list functor. And yes, C=D= category of (a subset of) Haskell types.

Are you saying the function that goes from list functor to singleton funtor is a natural transformation?

Here *singleton* is the natural transformation from the identity functor to the list functor. Daryoush Mehrtash-2 wrote:

But aren't they functors to different subset of Haskell Types?

They're usually treated as endofunctors on Hask, for reasons Ross Paterson has given. -- View this message in context: http://www.nabble.com/Functor-and-Haskell-tp23166441p23189784.html Sent from the Haskell - Haskell-Cafe mailing list archive at Nabble.com.