Implement TypeDefinitionRequest

[alanz]

Implement TypeDefinitionRequest so that we can go to the definition of the type of a variable etc.

[fendor]

I would be interested in implementing this feature, but I require a little guidance.

[lukel97]

You'll probably want to start by adding in a handler for ReqTypeDefinition inside LspStdio.hs, somewhere near here:

haskell-ide-engine/src/Haskell/Ide/Engine/Transport/LspStdio.hs

Lines 696 to 705 in e1aeb18

	ReqDefinition req -> do
	liftIO $ U.logs $ "reactor:got DefinitionRequest:" ++ show req
	let params = req ^. J.params
	doc = params ^. J.textDocument . J.uri
	pos = params ^. J.position
	callback = reactorSend . RspDefinition . Core.makeResponseMessage req
	let hreq = IReq tn (req ^. J.id) callback
	$ fmap J.MultiLoc <$> Hie.findDef doc pos
	makeRequest hreq

And from then you can probably try seeing how ReqDefinition plugs into GhcMod to gather information. Hopefully this helps

[fendor]

I finally have the time to work on this issue, but I have to ask, due to the lack of documentation, what is this Request supposed to do?
My gut feeling is that it shows me the definition of a Type.
When I press ctrl+left click on a type in VSCode it already sends me to the Definition of that type, so it seems the TypeDefinitionRequest does something else?

[lukel97]

The go to type definition request is sent from the client to the server to resolve the type definition location of a symbol at a given text document position.

The specification is pretty vague I agree, from what I can grok from it I think its for jumping to the definition of a type for an expression/value. i.e. it looks up the type of what was just clicked, and then jumps to that type