Hi Felipe,
On Wed, Apr 7, 2010 at 3:09 PM, Felipe Lessa
On Wed, Apr 07, 2010 at 11:13:02AM +0200, Bas van Dijk wrote:
I would like to propose adding a flipped variant of <$> to Data.Functor:
(<$$>) ∷ Functor f ⇒ f α → (α → β) → f β (<$$>) = flip (<$>)
+1
I've needed <$$> many times and had to use 'flip fmap' instead.
In my opinion this is not a good criteria for including a function. For any function composition you can find a subset of the community that uses that particular composition. Yet, if we add all the function compositions that some group of people use in their code our APIs get much more complicated. To make matters worse, the incentives for arguing for and against any particular addition are somewhat perverse: The people who use the particular composition think it's a great idea, they can make their own code a bit more beautiful. The people who don't use it would perhaps prefer to not see it added but it's time consuming to argue against every single proposal and the benefit to get any particular proposal rejected is small. This is how many APIs at [work] got more complicated. Someone argues very strongly that they need this particular addition and the maintainer gets many addition proposals. Eventually he/she gives in. After some time someone rewrites the library from scratch as it's to hard to understand anymore. -- Johan