[Haskell-cafe] Trouble defining `instance Arrow SF'
dmbarbour at gmail.com
Fri Oct 28 06:46:08 CEST 2011
On Thu, Oct 27, 2011 at 7:07 PM, Captain Freako <capn.freako at gmail.com>wrote:
> Thanks for the reply, David.
> I tried implementing your suggestions, such that my code now looks like
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`.
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