Inserting instance initial body now works :)

Language/Haskell/GhcMod/Rewrite.hs

@@ -252,7 +252,7 @@ initialBody fname args =
     arglist -> if isSymbolName fname
                then (head arglist) ++ " " ++ fname ++ " " ++ (intercalate " " (tail arglist))
                else fname ++ " " ++ (intercalate " " arglist)
-  ++ " = _" ++ fname ++ "_body"
+  ++ " = " ++ (if isSymbolName fname then "" else '_':fname) ++ "_body"
 
 initialBodyArgs :: [FnArg] -> [String] -> [String] -> [String]
 initialBodyArgs [] _ _ = []

elisp/ghc-rewrite.el

@@ -39,4 +39,31 @@
 	 (cmd (format "split %s %s %s\n" file ln cn)))
     (ghc-sync-process cmd)))
 
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+;;;
+;;; Initial code from signature
+;;;
+
+(defun ghc-initial-code-from-signature ()
+  (interactive)
+  (let ((info (ghc-obtain-initial-code-from-signature)))
+    (if (null info)
+	(message "Cannot obtain initial code")
+	(let* ((ln-current (line-number-at-pos))
+	       (pos (car info))
+	       (ln-end (ghc-sinfo-get-end-line pos))
+	       (ln-diff (+ 1 (- ln-end ln-current)))
+	       (fns-to-insert (cadr info)))
+	  (goto-char (line-end-position ln-diff))
+	  (dolist (fn-to-insert fns-to-insert)
+	    (newline-and-indent)
+	    (insert fn-to-insert))))))
+
+(defun ghc-obtain-initial-code-from-signature ()
+  (let* ((ln (int-to-string (line-number-at-pos)))
+	 (cn (int-to-string (1+ (current-column))))
+	 (file (buffer-file-name))
+	 (cmd (format "sig %s %s %s\n" file ln cn)))
+    (ghc-sync-process cmd)))
+
 (provide 'ghc-rewrite)

elisp/ghc.el

@@ -74,6 +74,7 @@
 (defvar ghc-shallower-key   "\C-c<")
 (defvar ghc-deeper-key      "\C-c>")
 (defvar ghc-case-split-key  "\C-c\C-p")
+(defvar ghc-initial-sig-key "\C-c\C-s")
 
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 ;;;
@@ -107,6 +108,7 @@
     (define-key haskell-mode-map ghc-shallower-key   'ghc-make-indent-shallower)
     (define-key haskell-mode-map ghc-deeper-key      'ghc-make-indent-deeper)
     (define-key haskell-mode-map ghc-case-split-key  'ghc-case-split)
+    (define-key haskell-mode-map ghc-initial-sig-key 'ghc-initial-code-from-signature)
     (ghc-comp-init)
     (setq ghc-initialized t))
   (ghc-import-module)