1 files changed, 30 insertions, 0 deletions
diff --git a/pkgs/build-support/emacs/elpa2nix.el b/pkgs/build-support/emacs/elpa2nix.el
new file mode 100644
index 00000000000..7eef81b9e7a
--- /dev/null
+++ b/pkgs/build-support/emacs/elpa2nix.el
@@ -0,0 +1,30 @@
+(require 'package)
+(package-initialize)
+
+(defun elpa2nix-install-package ()
+  (if (not noninteractive)
+      (error "`elpa2nix-install-package' is to be used only with -batch"))
+  (pcase command-line-args-left
+    (`(,archive ,elpa)
+     (progn (setq package-user-dir elpa)
+            (elpa2nix-install-file archive)))))
+
+(defun elpa2nix-install-from-buffer ()
+  "Install a package from the current buffer."
+  (let ((pkg-desc (if (derived-mode-p 'tar-mode)
+                      (package-tar-file-info)
+                    (package-buffer-info))))
+    ;; Install the package itself.
+    (package-unpack pkg-desc)
+    pkg-desc))
+
+(defun elpa2nix-install-file (file)
+  "Install a package from a file.
+The file can either be a tar file or an Emacs Lisp file."
+  (let ((is-tar (string-match "\\.tar\\'" file)))
+    (with-temp-buffer
+      (if is-tar
+          (insert-file-contents-literally file)
+        (insert-file-contents file))
+      (when is-tar (tar-mode))
+      (elpa2nix-install-from-buffer))))