haskell-hoogle command's *hoogle* window results are not clickable

[dmich2]

When I get haskell-hoogle results in the *hoogle* window (as opposed to opening hoogle results in browser), I am unable to get any further details on the choices shown. I can't select an entry and hit <Return> for example to see the details on the chosen function.

[geraldus]

@dmich2, thanks. However, now I'm thinking about what that further details should actually be, I mean what information you expect to see and where to get it from?

[dmich2]

For example, if in a haskell buffer I type he, company-mode pops up a list that shows head Prelude. If I then hit <F1> it shows in *company-documentation* buffer:

Prelude head :: [a] -> a

Extract the first element of a list, which must be non-empty. 

From package base
head :: [a] -> a

See https://github.com/iquiw/company-ghc#34display-hoogle-document-as-doc-buffer for a screen-shot.

[dmich2]

Possibly related to issue #215

[geraldus]

@dmich2 good, I ask because I'm not using hoodle in Emacs, so I do not know what it can. Maybe this is a time to get used. So, we can get some detailed documentation from hoogle indeed.

@gracjan What will you say, it looks like reasonable addition to functionality? I vote for clickable search results in hoogle buffer, it should not be hard to implement this I guess.

[gracjan]

Can either of you or both write a more detailed specification how this should be implemented?

We need a spec that is detailed enough so it deserves 'well-defined-task' label.

[geraldus]

@gracjan I did some research.

First,

If prefix argument INFO is given, then `haskell-hoogle-command' is asked to show extra info for the items matching QUERY..

But it shows extra documentation only for single entry, not for whole list, e.g.
(haskell-hoogle "map") gives long list of matching results,
while (haskell-hoogle "map" t) shows documentation only for Prelude.map.

This function relies on external hoogle executable.

So, we can achieve our goal only if:

• we'll write some hoogle output parsing
• if there is an easy way to find identifiers in output, then we can make them clickable. The easiest way to implement navigation is to execute same haskell-hoogle command with clicked item as QUERY argument and prefix argument set to t, e.g.

haskell-hoogle "map":
Prelude map :: (a -> b) -> [a] -> [b]
Data.List map :: (a -> b) -> [a] -> [b]
…

when clicked on Data.List map execute (haskell-hoogle "Data.List.map" t). One caveat is [back] button. Hoogle command provide results in its own buffer, maybe if we can post output to Help buffer, Emacs will manage back and forward buttons manually.