Added support for user configuration

[colbyn]

This is something I added a little while ago and thought others may find this useful (includes a doc file ./docs/hie-yaml-file.md).

The primary feature is to just simply disable interactive (as you type) analysis, as mentioned in the ./docs/hie-yaml-file.md file. For a reference the RLS project has a similar option called build_on_save (https://github.com/rust-lang/rls#configuration).

[lukel97]

Could these options be added to the LSP configuration settings, instead of creating a new file/format?

haskell-ide-engine/hie-plugin-api/Haskell/Ide/Engine/Config.hs

Lines 21 to 29 in 7dd6fd7

	data Config =
	Config
	{ hlintOn :: Bool
	, maxNumberOfProblems :: Int
	, diagnosticsDebounceDuration :: Int
	, liquidOn :: Bool
	, completionSnippetsOn :: Bool
	, formatOnImportOn :: Bool
	} deriving (Show,Eq)

[colbyn]

Certainly.

I’ve just implemented the necessary changes for using the preexisting settings format, and updated the README.md file. I’m not sure how it’s supposed to work in general. Perhaps it’s editor specific, yet for the life of me I couldn’t figure out how the json value/file is exchanged (from looking at the getConfigFromNotification function)…

So as a workaround if the value isn’t available it defaults to checking for a settings.json file that then defaults to the Default instance, i.e. configVal (onSaveOnly configFile) onSaveOnly >>= \case.

I suppose the name of this branch doesn’t make any sense now. I wasn’t sure what to rename it to so I left it as is.

[alanz]

@colbyn

The settings.json format is described so that LSP clients can know what options to provide when sending the configuration message through. So strictly speaking managing settings is a client issue, not a server issue.

It is also not clear to my whether the onSaveOnly mechanism is the right one to use for this, the flag makes sense, but I am not sure whether it should rather be implemented via the TextDocumentSyncKind setting for TextDocumentSyncOptions from the server, to switch it from incremental to full.

[lukel97]

@colbyn The settings.json location depends on the client, for LanguageClient-neovim it should be in .vim/settings.json. For VS Code you need to expose it via the extension, which is done in javascript. I recently created a PR to add a new option to it here