use prompt proc arity instead of to_ary. God this is boring

Rakefile

@@ -44,7 +44,7 @@ task :default => [:test]
 desc "Run tests"
 task :test do
   check_dependencies unless ENV['SKIP_DEP_CHECK']
-  sh "bacon -Itest -rubygems -a -q"
+  sh "bacon -Itest -rubygems"
 end
 
 desc "Run pry"

lib/pry/pry_instance.rb

@@ -645,14 +645,23 @@ class Pry
 
     # If input buffer is empty then use normal prompt
     if eval_string.empty?
-      Array(prompt).first.call(c)
+      generate_prompt(Array(prompt).first, c)
 
     # Otherwise use the wait prompt (indicating multi-line expression)
     else
-      Array(prompt).last.call(c)
+      generate_prompt(Array(prompt).last, c)
     end
   end
 
+  def generate_prompt(prompt_proc, conf)
+    if prompt_proc.arity == 1
+      prompt_proc.call(conf)
+    else
+      prompt_proc.call(conf.object, conf.nesting_level, conf._pry_)
+    end
+  end
+  private :generate_prompt
+
   # the array that the prompt stack is stored in
   def prompt_stack
     @prompt_stack ||= Array.new