Talk:Haskell/The Functor class

Etymology
I wish there was something about the etymology of the name "Functor" but I don't know what it is, so I can't write it myself.Backfromquadrangle (discuss • contribs) 18:28, 1 May 2014 (UTC)


 * It is probably less interesting than you expect :) It's just that the pioneer category theorists, when faced with the problem of naming the implausibly general concepts they had defined, chose to borrow evocative terms from philosophy ("category" from Aristotle and Kant; "functor" from Carnap; "monad" from Leibniz). There is no real technical connection though. [This page http://jeff560.tripod.com/f.html] mentions a few more historical details. --Duplode (discuss • contribs) 16:33, 2 May 2014 (UTC)

enforcement of functor laws
I'm a beginner and just read through this section for the first time. The section on functor laws immediately prompts the question: Are these laws enforced? After all, functions are not in the Eq class. A quick search suggests the answer is no. Given that, I think it would be helpful to have a little more detail on what goes wrong if the functor laws are not obeyed. I'm sure it's more than just a stylistic difference, where others will not be able to make sense of your code easily, but it's difficult to gleam that just from what's written in this section.


 * On "what goes wrong": In a nutshell, a class like  expresses some concept, and the laws make sure the instances actually match the concept. If   is a , we expect that   will use the   function to change the   values found in the  , and that it won't do anything else -- the laws guarantee that is the case. Later I will try to figure out a way to say a little more about that in the book text. Thanks, and cheers, Duplode (discuss • contribs) 15:28, 14 August 2018 (UTC)