Javascript scope is hard

fizzbuzz.mc

-(include str)
-(def fizzbuzz
-  (assign i 1)
-  (repeat $1
-    (assign result "")
-    (if (eq (modulo i 3) 0) (assign result (str::concat result "Fizz")))
-    (if (eq (modulo i 5) 0) (assign result (str::concat result "Buzz")))
-    (if (eq result "") (assign result i))
-    (log result)
-    (assign i (add i 1))
-  )
-)
-
-(fizzbuzz 100)

fizzbuzz.mc.js

+var _ = require("./lib/stdlib.js")(this)
+var _str = require("./lib/str.js")(this);
+_.def(_.ref('fizzbuzz'), function() { 
+_.assign(_.ref('i'), {value: 1});
+_.repeat(arguments[0], function() { 
+_.assign(_.ref('result'), { value: '' });
+_.if(_.eq(_.modulo(_.ref('i'), {value: 3}), {value: 0}), function() { 
+_.assign(_.ref('result'), _str.concat(_.ref('result'), { value: 'Fizz' }));
+});
+_.if(_.eq(_.modulo(_.ref('i'), {value: 5}), {value: 0}), function() { 
+_.assign(_.ref('result'), _str.concat(_.ref('result'), { value: 'Buzz' }));
+});
+_.if(_.eq(_.ref('result'), { value: '' }), function() { 
+_.assign(_.ref('result'), _.ref('i'));
+});
+_.log(_.ref('result'));
+_.assign(_.ref('i'), _.add(_.ref('i'), {value: 1}));
+});
+});
+_.fizzbuzz({value: 100});

lib/stdlib.js

     function_defs[prop.name] = body;
   },
   repeat: function (amount, body) {
-    for (ii = 0 ; ii < amount.value; ii++) {
+    for (let i = 0 ; i < amount.value; i++) {
         body.bind(_)() 
     }
   },

lib/str.js

 const builtins = {
   concat: function () {
     let str = ""
-    for (i = 0; i < arguments.length; i++) {
+    for (let i = 0; i < arguments.length; i++) {
       str += arguments[i].value
     }
     return {