Add support for cabal-fmt to haskell mode

nix/modules/haskell/default.nix

@@ -48,6 +48,7 @@ in
 
     fg42.paths = (with pkgs;[
       haskell-language-server
+      haskellPackages.cabal-fmt
       ghc
     ]);
 

nix/modules/haskell/lisp/fg42/haskell-support.el

@@ -78,7 +78,8 @@
   (haskell-mode . turn-on-haskell-doc-mode)
   (haskell-mode . haskell-indentation-mode)
   (haskell-mode . haskell-setup-outline-mode)
-
+  (haskell-mode . (lambda ()
+                    (require 'haskell-commands)))
   :bind
   (:map haskell-mode-map
         ("M-n" . haskell-goto-next-error)
@@ -86,9 +87,18 @@
         ("C-c c" . haskell-compile)))
 
 
+(cl-defmethod fg42/format-buffer-for ((mode (eql haskell-cabal-mode)))
+  "Use `cabal-fmt' to format the buffer whenever `haskell-cabal-mode' MODE is active."
+  (message "hehehehehehe")
+  (haskell-mode-buffer-apply-command "cabal-fmt"))
+
+
 (use! haskell-cabal-mode
   "Cabal integration."
-  :mode ("\\.cabal\\'"))
+  :mode ("\\.cabal\\'")
+  :hook (haskell-cabal-mode . (lambda ()
+                                (require 'haskell-commands))))
+
 
 
 (provide 'fg42/haskell-support)