diff --git a/bin/keisan b/bin/keisan
index 374b0d4..ba25fce 100755
--- a/bin/keisan
+++ b/bin/keisan
@@ -2,6 +2,17 @@
 
 require "bundler/setup"
 require "keisan"
-require "keisan/repl"
+require "keisan/interpreter"
 
-Keisan::Repl.new.start
+file_name = nil
+allow_recursive = false
+
+ARGV.each do |arg|
+  if arg == "--allow_recursive"
+    allow_recursive = true
+  else
+    file_name = arg
+  end
+end
+
+Keisan::Interpreter.new(allow_recursive: allow_recursive).run(file_name)
diff --git a/lib/keisan/interpreter.rb b/lib/keisan/interpreter.rb
new file mode 100644
index 0000000..03f0172
--- /dev/null
+++ b/lib/keisan/interpreter.rb
@@ -0,0 +1,40 @@
+module Keisan
+  class Interpreter
+    attr_reader :calculator
+
+    def initialize(allow_recursive: false)
+      @calculator = Calculator.new(allow_recursive: allow_recursive)
+    end
+
+    def run(file_name)
+      if file_name.nil?
+        run_from_stdin
+      else
+        run_from_file(file_name)
+      end
+    end
+
+    private
+
+    def run_from_stdin
+      run_on_content STDIN.read
+    end
+
+    def run_from_file(file_name)
+      run_on_content(
+        File.exists?(file_name) ? File.open(file_name) do |file|
+          file.read
+        end : ""
+      )
+    end
+
+    def run_on_content(content)
+      content = content.strip
+      if content.nil? || content.empty?
+        Repl.new.start
+      else
+        calculator.evaluate(content)
+      end
+    end
+  end
+end
diff --git a/lib/keisan/repl.rb b/lib/keisan/repl.rb
index a06fb6d..c2e4b48 100644
--- a/lib/keisan/repl.rb
+++ b/lib/keisan/repl.rb
@@ -1,4 +1,4 @@
-require "pry"
+require "coderay"
 require "readline"
 
 module Keisan