bin/p-lang in p-lang-0.2.0 vs bin/p-lang in p-lang-0.3.0

@@ -12,11 +12,16 @@
     sa = PLang::Parser::SyntaxAnalyser.new(command)
     vm = PLang::VM::Interpreter.new(sa.parse)
     vm.execute!
   end
 
-  opts.on("-i", "-i FILE", "interp a script file.") do |file|
+  opts.on("-i", "-i", "interactive p shell.") do
+    shell = PLang::IPS::Shell.new
+    shell.start
+  end
+
+  opts.on("-f", "-f FILE", "interp a script file.") do |file|
     begin
       program = File.readlines(file).join("")
     rescue
       puts "No such file (LoadError)"
       exit
@@ -33,13 +38,14 @@
 
 argv = ARGV
 begin
   if ARGV.length > 0
     if options.parse!(ARGV).length > 0
-      options.parse!(["-h"])
+      options.parse!(["-f" + ARGV[0]])
     end
   else
-    options.parse!(["-h"])
+    # without arguments
+    options.parse!(["-i"])
   end
 rescue
   puts "p-lang: unrecognized option"
 end