diff --git a/lib/imbecile.rb b/lib/imbecile.rb
index 4110a7a..2580b3c 100644
--- a/lib/imbecile.rb
+++ b/lib/imbecile.rb
@@ -1,2 +1,15 @@
 require_relative "imbecile/cli"
+require_relative "imbecile/grammar_parser"
 require_relative "imbecile/version"
+
+module Imbecile
+
+  class << self
+
+    def run(input_file)
+      gp = GrammarParser.new(input_file)
+    end
+
+  end
+
+end
diff --git a/lib/imbecile/cli.rb b/lib/imbecile/cli.rb
index 444f9f1..55350f0 100644
--- a/lib/imbecile/cli.rb
+++ b/lib/imbecile/cli.rb
@@ -36,6 +36,11 @@ EOF
           $stderr.puts "Error: must specify input file"
           return 1
         end
+        unless File.readable?(input_file)
+          $stderr.puts "Error: cannot read #{input_file}"
+          return 2
+        end
+        Imbecile.run(input_file)
       end
 
     end
diff --git a/lib/imbecile/grammar_parser.rb b/lib/imbecile/grammar_parser.rb
new file mode 100644
index 0000000..b187c2c
--- /dev/null
+++ b/lib/imbecile/grammar_parser.rb
@@ -0,0 +1,8 @@
+module Imbecile
+  class GrammarParser
+
+    def initialize(input_file)
+    end
+
+  end
+end