diff --git a/README.md b/README.md
index ab88dbe..eceac8b 100644
--- a/README.md
+++ b/README.md
@@ -6,9 +6,8 @@
 
 ```
 print_range = λ(a, b) if a <= b {
-                        print(a);
+                        println(a);
                         if a + 1 <= b {
-                          print(", ");
                           print_range(a + 1, b);
                         } 
                         else 
@@ -18,7 +17,16 @@ print_range(1, 10);
 ```
 output:
 ```
-1, 2, 3, 4, 5, 6, 7, 8, 9, 10
+1
+2
+3
+4
+5
+6
+7
+8
+9 
+10
 ***Result: false
 ```
 
diff --git a/bin/lambda b/bin/lambda
new file mode 100644
index 0000000..9cd6a46
--- /dev/null
+++ b/bin/lambda
@@ -0,0 +1,22 @@
+#!/usr/bin/env node
+
+let InputStream = require('../src/InputStream')
+let TokenStream = require('../src/TokenStream')
+let parser = require('../src/parser')
+let Environment = require('../src/Environment')
+
+const fs = require('fs')
+
+let args = process.argv
+code = fs.readFileSync(args[2]).toString()
+
+let globalEnv = new Environment()
+ast = parser(TokenStream(InputStream(code)))
+
+globalEnv.def('println', (val) => {
+    console.log(val)
+})
+
+// globalEnv.def('readFileSync', ())
+
+Environment.evaluate(ast, globalEnv)
\ No newline at end of file
diff --git a/demo b/demo
new file mode 100644
index 0000000..9e3bcd5
--- /dev/null
+++ b/demo
@@ -0,0 +1,21 @@
+print_range = λ(a, b) if a <= b {
+                        println(a);
+                        if a + 1 <= b {
+                          print_range(a + 1, b);
+                        } 
+                        else 
+                          println("");
+                      };
+print_range(1, 10);
+
+cons = λ(a, b) λ(f) f(a, b);
+car = λ(cell) cell(λ(a, b) a);
+cdr = λ(cell) cell(λ(a, b) b);
+NIL = λ(f) f(NIL, NIL);
+
+x = cons(1, cons(2, cons(3, cons(4, cons(5, NIL)))));
+println(car(x));                      # 1
+println(car(cdr(x)));                 # 2
+println(car(cdr(cdr(x))));            # 3
+println(car(cdr(cdr(cdr(x)))));       # 4
+println(car(cdr(cdr(cdr(cdr(x))))));  # 5
\ No newline at end of file
diff --git a/package.json b/package.json
index eada0af..ac5823e 100644
--- a/package.json
+++ b/package.json
@@ -1,10 +1,10 @@
 {
   "name": "implement-a-pl",
-  "version": "0.0.1",
+  "version": "0.1.0",
   "description": "compiler",
   "main": "index.js",
   "scripts": {
-    "test": "test"
+    "test": "node ./bin/lambda ./demo"
   },
   "keywords": [
     "compiler"
diff --git a/src/Environment.js b/src/Environment.js
index 6ae3122..b383092 100644
--- a/src/Environment.js
+++ b/src/Environment.js
@@ -96,6 +96,7 @@ class Environment {
     }
 }
 
+Environment.evaluate = evaluate
 
 
 
@@ -292,41 +293,5 @@ function makeLambda(expr, env) {
     }
 }
 
-// Primitive functions
-
-// let code = 'sum = λ(x, y) x + y; println(sum(2, 3.5));'
-let code = 
-`
-# demo1
-print_range = λ(a, b) if a <= b {
-                        println(a);
-                        if a + 1 <= b {
-                          print_range(a + 1, b);
-                        } 
-                        else 
-                            println("");
-                      };
-print_range(1, 100);
-
-# demo2
-cons = λ(a, b) λ(f) f(a, b);
-car = λ(cell) cell(λ(a, b) a);
-cdr = λ(cell) cell(λ(a, b) b);
-NIL = λ(f) f(NIL, NIL);
-
-x = cons(1, cons(2, cons(3, cons(4, cons(5, NIL)))));
-println(car(x));                      # 1
-println(car(cdr(x)));                 # 2
-println(car(cdr(cdr(x))));            # 3
-println(car(cdr(cdr(cdr(x)))));       # 4
-println(car(cdr(cdr(cdr(cdr(x))))));  # 5
-`
-let ast = parser(TokenStream(InputStream(code)))
-
-let globalEnv = new Environment()
-
-globalEnv.def('println', (val) => {
-    console.log(val)
-})
-
-evaluate(ast, globalEnv)
\ No newline at end of file
+module.exports = Environment
+// Primitive functions
\ No newline at end of file