adds if and filter

desktop/sources/scripts/library.js

@@ -66,6 +66,10 @@ function Library (ronin) {
     return arr.map(fn)
   }
 
+  this.filter = (fn, arr) => {
+    return arr.filter(fn)
+  }
+
   this.first = (arr) => {
     return arr[0]
   }
@@ -155,7 +159,12 @@ function Library (ronin) {
   this.mul = function (a, b) {
     return a * b
   }
+
   this.div = function (a, b) {
     return a / b
   }
+
+  this.mod = function (a, b) {
+    return a % b
+  }
 }

desktop/sources/scripts/lisp.js

@@ -35,6 +35,13 @@ function Lisp (input, lib) {
 
         return interpret(input[2], new Context(lambdaScope, context))
       }
+    },
+
+    if: function (input, context) {
+      if (interpret(input[1], context)) {
+        return interpret(input[2], context)
+      }
+      return interpret(input[3], context)
     }
   }