Guess a project's setting from it's .cabal file

A generalised version of what I proposed in haskell#464.

Author: ivan-m

haskell-cabal.el

@@ -179,6 +179,20 @@
               (setq val (replace-match "" t t val))))
           val)))))
 
+;;;###autoload
+(defun haskell-guess-setting (name)
+  "Guess the specified setting of this project.
+If there is no valid .cabal file to get the setting from (or
+there is no corresponding setting with that name in the .cabal
+file), then this function returns nil."
+  (interactive)
+  (when (and name buffer-file-name)
+    (let ((cabal-file (haskell-cabal-find-file (file-name-directory buffer-file-name))))
+      (when (and cabal-file (file-readable-p cabal-file))
+        (with-temp-buffer
+          (insert-file-contents cabal-file)
+          (haskell-cabal-get-setting name))))))
+
 ;;;###autoload
 (defun haskell-cabal-get-dir ()
   "Get the Cabal dir for a new project. Various ways of figuring this out,