CodeAction to create Haddock comments

[spacekitteh]

This would be super useful.

[ndmitchell]

What do you imagine it doing? Just inserting -- |? I wouldn't have thought that was that helpful - do you think it is? Or were you thinking of something more? When would this code action appear?

[spacekitteh]

Well, let's take a function definition. It should create a comment for the overall definition; further, it should create a comment for each argument. I wish Haddock had more expressive markup, because I would quite like to automatically insert a bunch of metadata tags too.

[cocreature]

So you would like a code action to turn:

f :: Int -> Int
f = …

into the following

-- | 
f :: Int {- ^ -} -> Int

That sounds doable although I’m not entirely sure it’s super useful since compared to writing the actual docs, inserting the comments seems trivial.

[hazelweakly]

Turning

data A = A { a :: T, b :: T }

into

data A = A
  { a :: T
    -- ^ ____
  , b :: T
    -- ^ ____
  }

and

f :: ( A a , B b , C c) => a -> b -> c -> (a,b,c)

into

f
  :: ( A a
     , B b
     , C c
     )
  => a -- ^ ____
  -> b -- ^ ____
  -> c -- ^ ____
  -> (a,b,c) -- ^ ____

would save a non trivial amount of typing and would be quite convenient, I think.
Sure writing the docs is effort, but this reduces the inital setup, especially for "trivial" docs.

(The underscores are denoting snippet placeholders that the language server can use to jump you to each spot where comments can be added)

[spacekitteh]

In addition to what @jared-w said, it would also help provide motivation to write docs. Who wants to see a bunch of useless comments? :D

[jneira]

I think this could be a plugin in hls, @ndmitchell @cocreature what do you think about translate this to hls?

[ndmitchell]

Definitely agreed - one for HLS. We should move most suggestions that can be implemented as HLS plugins, and don't reflect things already in Ghcide, over to HLS.