Re: Polymorphism in the Prelude

On 06/25/2014 01:10 AM, Edward Kmett wrote:

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On Jun 24, 2014, at 3:08 PM, Daniel Gorín wrote:

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On Tue, Jun 24, 2014 at 3:42 AM, Mateusz Kowalczyk wrote: Do you have anything specific in mind here? At first I was just going to dismiss this as wishful thinking but perhaps we could actually do something about this.

Maybe we could provide ‘alternative’ signatures which would make types more specific with some (which? all of known ones?) instances.

One thing that might help is to list the specific type of methods below instance declarations, in a collapsible view to avoid cluttering. An example rendering (in "expanded view") would be:

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[-] instance Functor ((->) r) where fmap :: (a -> b) -> (r -> a) -> (r -> b)

Being able to "open" an instance line in haddock to see what it means could be quite useful. It'd likely require a fair bit of work in haddock though as it'd have to synthesize that information somehow.

I think that it might not be very hard to get this information from GHC for regular typeclasses although it might be harder for TFs &c. I think presentation is a big problem here and the rest is just figuring out how to use the GHC API to spit out what we need. -- Mateusz K.