Use Promise constructor instead of Promise.defer. Fix #110.

lib/ex.coffee

@@ -4,11 +4,10 @@ fs = require 'fs-plus'
 VimOption = require './vim-option'
 
 trySave = (func) ->
-  deferred = Promise.defer()
-
+  new Promise (resolve) ->
     try
       func()
-    deferred.resolve()
+      resolve()
     catch error
       if error.message.endsWith('is a directory')
         atom.notifications.addWarning("Unable to save file: #{error.message}")
@@ -30,7 +29,6 @@ trySave = (func) ->
       else
         throw error
 
-  deferred.promise
 
 saveAs = (filePath) ->
   editor = atom.workspace.getActiveTextEditor()
@@ -150,7 +148,7 @@ class Ex
     if filePath.indexOf(' ') isnt -1
       throw new CommandError('Only one file name allowed')
 
-    deferred = Promise.defer()
+    new Promise (resolve) ->
 
       editor = atom.workspace.getActiveTextEditor()
       saved = false
@@ -158,7 +156,7 @@ class Ex
         fullPath = getFullPath(filePath)
       if editor.getPath()? and (not fullPath? or editor.getPath() == fullPath)
         # Use editor.save when no path is given or the path to the file is given
-      trySave(-> editor.save()).then(deferred.resolve)
+        trySave(-> editor.save()).then(resolve)
         saved = true
       else if not fullPath?
         fullPath = atom.showSaveDialogSync()
@@ -166,9 +164,7 @@ class Ex
       if not saved and fullPath?
         if not force and fs.existsSync(fullPath)
           throw new CommandError("File exists (add ! to override)")
-      trySave(-> saveAs(fullPath)).then(deferred.resolve)
-
-    deferred.promise
+        trySave(-> saveAs(fullPath)).then(resolve)
 
   w: (args...) =>
     @write(args...)