MonkeyPatch jruby's Array#pretty_inspect [Fixes #568]

lib/pry/core_extensions.rb

@@ -51,3 +51,24 @@ class Object
     __binding_impl__
   end
 end
+
+# There's a splat bug on jruby in 1.9 emulation mode, which breaks the
+# pp library.
+#
+# * http://jira.codehaus.org/browse/JRUBY-6687
+# * https://github.com/pry/pry/issues/568
+#
+# Until that gets fixed upstream, let's monkey-patch here:
+if [[1, 2]].pretty_inspect == "[1]\n"
+  class Array
+    def pretty_print(q)
+      q.group(1, '[', ']') {
+        i = 0
+        q.seplist(self) { |*|
+          q.pp self[i]
+          i += 1
+        }
+      }
+    end
+  end
+end