Add formatter configuration

Author: notogawa

README.md

@@ -79,6 +79,9 @@ exposed via a set of interactive functions.
 - `lsp-haskell-set-completion-snippets-on` /
   `lsp-haskell-set-completion-snippets-off` Whether completion should
   return plain text or snippets.
+- `lsp-haskell-set-formatter-brittany` /
+  `lsp-haskell-set-formatter-floskell` /
+  `lsp-haskell-set-formatter-ormolu` Set code formatter.
 
 There are also non-interactive versions that do not actually send the
 settings to the live server, but are suitable for use in `.dir-locals`
@@ -88,3 +91,4 @@ for a specific project.
 - `lsp-haskell-set-max-problems`
 - `lsp-haskell-set-liquid`
 - `lsp-haskell-set-completion-snippets`
+- `lsp-haskell-set-formatter`

lsp-haskell.el

@@ -290,6 +290,29 @@ These are assembled from the customizable variables
   (lsp-haskell-set-completion-snippets :json-false)
   (lsp-haskell--set-configuration))
 
+;; -------------------------------------
+
+(defun lsp-haskell-set-formatter (val)
+  "Set code formatter."
+  (lsp-haskell-set-config "formattingProvider" val))
+
+(defun lsp-haskell-set-formatter-brittany ()
+  "Use brittany."
+  (interactive)
+  (lsp-haskell-set-formatter :brittany)
+  (lsp-haskell--set-configuration))
+
+(defun lsp-haskell-set-formatter-floskell ()
+  "Use floskell."
+  (interactive)
+  (lsp-haskell-set-formatter :floskell)
+  (lsp-haskell--set-configuration))
+
+(defun lsp-haskell-set-formatter-ormolu ()
+  "Use ormolu."
+  (interactive)
+  (lsp-haskell-set-formatter :ormolu)
+  (lsp-haskell--set-configuration))
 
 ;; ---------------------------------------------------------------------