diff --git a/desktop/sources/scripts/library.js b/desktop/sources/scripts/library.js
index c962ad5..fb505f9 100644
--- a/desktop/sources/scripts/library.js
+++ b/desktop/sources/scripts/library.js
@@ -265,6 +265,17 @@ function Library (ronin) {
 
   this.TWO_PI = Math.PI * 2
 
+  this.random = (...args) => {
+    if (args.length >= 2) {
+      // (random start end)
+      return args[0] + Math.random() * (args[1] - args[0])
+    } else if (args.length === 1) {
+      // (random max)
+      return Math.random() * args[0]
+    } 
+    return Math.random()
+  }
+
   // Generics
 
   this.echo = (...args) => {
@@ -299,4 +310,8 @@ function Library (ronin) {
   // Livecoding
 
   this.time = Date.now
+
+  // javascript interop
+  this.js = window
+
 }
diff --git a/desktop/sources/scripts/lisp.js b/desktop/sources/scripts/lisp.js
index e308c52..a7c35af 100644
--- a/desktop/sources/scripts/lisp.js
+++ b/desktop/sources/scripts/lisp.js
@@ -38,6 +38,17 @@ function Lisp (input, lib) {
       context.scope[input[1].value] = interpret(input[2], context)
       return input[2]
     },
+    defn: function(input, context) {
+      context.scope[input[1].value] = function() {
+        const lambdaArguments = arguments
+        const lambdaScope = input[2].reduce(function (acc, x, i) {
+          acc[x.value] = lambdaArguments[i]
+          return acc
+        }, {})
+
+        return interpret(input[3], new Context(lambdaScope, context))
+      }
+    },
     lambda: function (input, context) {
       return function () {
         const lambdaArguments = arguments
diff --git a/examples/benchmark.lisp b/examples/benchmark.lisp
index a1be15d..ba1265c 100644
--- a/examples/benchmark.lisp
+++ b/examples/benchmark.lisp
@@ -46,8 +46,13 @@
   (def addOne (lambda (a) (add a 1)))
   (test "def - value" aaa 123)
   (test "def - func" (addOne 4) 5)
+  (defn addTwo (a) (add 2 a))
+  (test "defn" (addTwo 4) 6)
 
 ; Generics
 
   (test "str" (str 1 4 "-" (add 3 4) ".jpg") "14-7.jpg")
+
+; Interop
+  (test "interop" ((of (of js "Math") "max") 2 4) 4)
 )
\ No newline at end of file