The locate-dominating-file function using a lambda doesn't work.

The function is applied to the directory name, thus string= looking
for .cabal-sandbox is not going to work.

Author: alexanderkjeldaas

haskell-process.el

@@ -535,15 +535,10 @@ to be loaded by ghci."
 (defun haskell-process-type ()
   "Return `haskell-process-type', or a guess if that variable is 'auto."
   (if (eq 'auto haskell-process-type)
-      (let ((nix-shell-found (locate-dominating-file default-directory
-                                               (lambda (f)
-                                                 (string= "shell.nix" f))))
-            (cabal-found (locate-dominating-file default-directory
-                                                 (lambda (f)
-                                                   (or (string= ".cabal-sandbox" f)
-                                                       (string-match-p "\\.cabal\\'" f))))))
-        (cond ((and cabal-found nix-shell-found) 'nix-shell-cabal-repl)
-              (cabal-found 'cabal-repl)
+      (let ((nix-shell-found (locate-dominating-file default-directory "shell.nix"))
+            (cabal-sandbox-found (locate-dominating-file default-directory ".cabal-sandbox")))
+        (cond ((and cabal-sandbox-found nix-shell-found) 'nix-shell-cabal-repl)
+              (cabal-sandbox-found 'cabal-repl)
               (nix-shell-found 'nix-shell-ghci)
               (t 'ghci)))
     haskell-process-type))