Added nix-shell-ghci support.

Author: alexanderkjeldaas

haskell-process.el

@@ -78,6 +78,19 @@
   :group 'haskell-interactive
   :type '(choice string (repeat string)))
 
+(defcustom haskell-process-path-nix-shell
+  "nix-shell"
+  "The path for starting nix-shell."
+  :group 'haskell-interactive
+  :type '(choice string (repeat string)))
+
+(defcustom haskell-process-args-nix-shell
+  '("nix/devel.nix")
+  "The path for starting nix-shell."
+  :group 'haskell-interactive
+  :type '(choice string (repeat string)))
+
+
 (defcustom haskell-process-args-ghci
   '("-ferror-spans")
   "Any arguments for starting ghci."
@@ -106,7 +119,8 @@ See `haskell-process-do-cabal' for more details."
 (defcustom haskell-process-type
   'ghci
   "The inferior Haskell process type to use."
-  :type '(choice (const ghci) (const cabal-repl) (const cabal-dev) (const cabal-ghci))
+  :type '(choice (const ghci) (const cabal-repl) (const cabal-dev)
+                 (const cabal-ghci) (const nix-shell-ghci))
   :group 'haskell-interactive)
 
 (defcustom haskell-process-log
@@ -504,7 +518,8 @@ for various things, but is optional."
   "Add <cabal-project-dir>/dist/build/autogen/ to the ghci search
 path. This allows modules such as 'Path_...', generated by cabal,
 to be loaded by ghci."
-  (unless (eq 'cabal-repl haskell-process-type) ;; redundant with "cabal repl"
+  (unless (or (eq 'cabal-repl haskell-process-type)  ;; redundant with "cabal repl"
+              (eq 'nix-shell-ghci haskell-process-type))
     (let*
         ((session       (haskell-session))
          (cabal-dir     (haskell-session-cabal-dir session))
@@ -527,13 +542,20 @@ to be loaded by ghci."
          (cadr state)
          (format haskell-process-do-cabal-format-string
                  (haskell-session-cabal-dir (car state))
-                 (format "%s %s"
+                 (format "%s %s %s"
                          (ecase haskell-process-type
                            ('ghci haskell-process-path-cabal)
                            ('cabal-repl haskell-process-path-cabal)
                            ('cabal-ghci haskell-process-path-cabal)
-                           ('cabal-dev haskell-process-path-cabal-dev))
-                         (caddr state)))))
+                           ('cabal-dev haskell-process-path-cabal-dev)
+                           ('nix-shell-ghci (concat haskell-process-path-nix-shell
+                                                    " "
+                                                    haskell-process-args-nix-shell
+                                                    " --command '")))
+                         (caddr state)
+                         (case haskell-process-type
+                           ('nix-shell-ghci "'")
+                           (t ""))))))
 
       :live
       (lambda (state buffer)
@@ -575,7 +597,8 @@ to be loaded by ghci."
                            ('ghci haskell-process-path-cabal)
                            ('cabal-repl haskell-process-path-cabal)
                            ('cabal-ghci haskell-process-path-cabal)
-                           ('cabal-dev haskell-process-path-cabal-dev))
+                           ('cabal-dev haskell-process-path-cabal-dev)
+                           ('nix-shell-ghci haskell-process-path-nix-shell))
                :app-icon haskell-process-logo
                )))))))))
 
@@ -1050,7 +1073,25 @@ now."
                            haskell-process-path-cabal-dev
                            "ghci"
                            "-s"
-                           dir))))))
+                           dir)))
+         ('nix-shell-ghci
+          (haskell-process-log
+           (propertize
+            (format "Starting inferior nix-shell (ghci) process using %s %s %s %s..."
+                    haskell-process-path-nix-shell
+                    haskell-process-args-nix-shell
+                    "--command"
+                    haskell-process-path-ghci)
+            'face font-lock-comment-face))
+          (apply #'start-process
+                 (append (list (haskell-session-name session)
+                               nil
+                               haskell-process-path-nix-shell)
+                         haskell-process-args-nix-shell
+                         '("--command")
+                         (list haskell-process-path-ghci)
+                         (let ((target (haskell-session-target session)))
+                           (if target (list target) nil))))))))
     (progn (set-process-sentinel (haskell-process-process process) 'haskell-process-sentinel)
            (set-process-filter (haskell-process-process process) 'haskell-process-filter))
     (haskell-process-send-startup process)