diff --git a/build.gradle b/build.gradle
index 8b113a8..c6bd69c 100644
--- a/build.gradle
+++ b/build.gradle
@@ -1,34 +1,23 @@
-/*
- * This file was generated by the Gradle 'init' task.
- *
- * This generated file contains a sample Java project to get you started.
- * For more details take a look at the Java Quickstart chapter in the Gradle
- * User Manual available at https://docs.gradle.org/6.0.1/userguide/tutorial_java_projects.html
- */
-
 plugins {
-    // Apply the java plugin to add support for Java
     id 'java'
-
-    // Apply the application plugin to add support for building a CLI application.
     id 'application'
 }
 
 repositories {
-    // Use jcenter for resolving dependencies.
-    // You can declare any Maven/Ivy/file repository here.
     jcenter()
 }
 
 dependencies {
-    // This dependency is used by the application.
     implementation 'com.google.guava:guava:28.0-jre'
-
-    // Use JUnit test framework
     testImplementation 'junit:junit:4.12'
 }
 
 application {
-    // Define the main class for the application.
-    mainClassName = 'serene.simple.App'
+    mainClassName = 'serene.simple.Main'
+}
+
+jar {
+    manifest {
+        attributes 'Main-Class': 'serene.simple.Main'
+    }
 }
diff --git a/src/main/java/serene/simple/App.java b/src/main/java/serene/simple/App.java
deleted file mode 100644
index c83116c..0000000
--- a/src/main/java/serene/simple/App.java
+++ /dev/null
@@ -1,14 +0,0 @@
-/*
- * This Java source file was generated by the Gradle 'init' task.
- */
-package serene.simple;
-
-public class App {
-    public String getGreeting() {
-        return "Hello world.";
-    }
-
-    public static void main(String[] args) {
-        System.out.println(new App().getGreeting());
-    }
-}
diff --git a/src/main/java/serene/simple/Main.java b/src/main/java/serene/simple/Main.java
new file mode 100644
index 0000000..bfbcfff
--- /dev/null
+++ b/src/main/java/serene/simple/Main.java
@@ -0,0 +1,46 @@
+/*
+ * This Java source file was generated by the Gradle 'init' task.
+ */
+package serene.simple;
+
+import java.io.IOException;
+import java.io.ByteArrayInputStream;
+import java.io.Console;
+import java.io.FileInputStream;
+
+
+public class Main {
+    public static void main(String[] args) throws IOException {
+        if (args.length == 0) {
+            startRepl();
+        }
+        runSerene(args[0]);
+    }
+
+    private static void startRepl() {
+        Environment rootEnv = Environment.getBaseEnvironment();
+
+        Console console = System.console();
+
+        while(true) {
+            String inputData = console.readLine("serene-> ");
+
+            if (expr == null) break;
+
+            ByteArrayInputStream inputStream = new ByteArrayInputStream(inputData.getBytes());
+            ListNode<Node> nodes = Reader.read(inputStream);
+            ...
+        }
+
+    }
+
+    private static void runSerene(String filePath) throws IOException {
+        Environment rootEnv = Environment.getBaseEnvironment();
+
+        ListNode<Node> nodes = Reader.read(new FileInputStream(filePath));
+
+        for (Node n : nodes) {
+            n.eval(rootEnv);
+        }
+    }
+}
diff --git a/src/test/java/serene/simple/AppTest.java b/src/test/java/serene/simple/MainTest.java
similarity index 58%
rename from src/test/java/serene/simple/AppTest.java
rename to src/test/java/serene/simple/MainTest.java
index d2bcdf4..1b419ea 100644
--- a/src/test/java/serene/simple/AppTest.java
+++ b/src/test/java/serene/simple/MainTest.java
@@ -6,9 +6,8 @@ package serene.simple;
 import org.junit.Test;
 import static org.junit.Assert.*;
 
-public class AppTest {
+public class MainTest {
     @Test public void testAppHasAGreeting() {
-        App classUnderTest = new App();
-        assertNotNull("app should have a greeting", classUnderTest.getGreeting());
+        Main classUnderTest = new Main();
     }
 }