Use stack ghci

Author: chrisdone

.dir-locals.el

@@ -2,4 +2,4 @@
                   (hindent-style . "johan-tibell")
                   (haskell-process-type . ghci)
                   (haskell-process-path-ghci . "stack")
-                  (haskell-process-args-ghci . ("exec" "ghci-ng")))))
+                  (haskell-process-args-ghci . ("ghci")))))