Re: [Haskell-cafe] Trouble defining `instance Arrow SF'

On Thu, Oct 27, 2011 at 7:07 PM, Captain Freako wrote:

Thanks for the reply, David. I tried implementing your suggestions, such that my code now looks like this:

While Ross Patterson followed Hughes closely, it was recognized that Category could be separated from Arrow. For `Category`, you must define (.) and id. There is a definition in the Control.Category module: (>>>) = flip (.) Thus, once you instance Category, you you get (>>>) for free. For Arrow, you must define `arr` and `first`. Regards, Dave