json encode in starlark

json-encode.py

# In a Starlark context that doesn't support json or recursion,
# you might become desperate enough to do something crazy like this...

def quoteIfString(obj):
  if type(obj) == "string":
    return '"' + obj + '"'
  else:
    return obj

def jsonEncode(obj):
  stack = [obj]
  json = ""

  for i in range(10000):
    if i >= len(stack):
      # empty stack!
      break
    item = stack[i]

    if type(item) == "list":
      x = []
      x.append("[")
      for j, elem in enumerate(item):
        if j > 0:
          x.append(",")
        x.append(quoteIfString(elem))
      x.append("]")
      stack = stack[:i+1] + x + stack[i+1:]
      continue

    if type(item) == "dict":
      x = []
      x.append("{")
      for j, elem in enumerate(item.items()):
        if j > 0:
          x.append(",")
        x.append(quoteIfString(elem[0]))
        x.append(":")
        x.append(quoteIfString(elem[1]))
      x.append("}")
      stack = stack[:i+1] + x + stack[i+1:]
      continue

    t = type(item)
    if t == "string":
      json += item # already quoted
    elif t == "bool":
      json += "true" if item else "false"
    elif t == "int":
      json += str(item)
    elif t == None:
      json += "null"
    else:
      return fail("Error: unsupported json type: " + t)

  return json

# P.S. This code is embarasingly bad. Please don't make me code it again in an interview.
# P.P.S. Yes, it works... for the limitted set of inputs I needed it to...