Lisp Tokenizer

import std/os
import std/streams
import std/deques

var strm = newFileStream(paramStr(1), fmRead)
var stack = initDeque[string]()
var arr = newSeq[string]()

proc startEnclosure(token: string) {.discardable.} =
  echo token
  stack.addFirst(token)
  arr.insert(token, 0)

proc endEnclosure(token: string) {.discardable.} =
  echo token
  discard stack.popFirst
  arr.insert(token, 0)

if not isNil(strm):
  while true:
    var s = strm.readChar()

    if s == '(':
      startEnclosure("<LIST START>")

    elif s == '#':
      if strm.peekChar() == '(':
        startEnclosure("<LAMBDA START>")
      elif strm.peekChar() == '{':
        startEnclosure("<SET START>")

    elif s == ')':
      if stack.peekFirst == "<LIST START>":
        endEnclosure("<LIST END>")
      elif stack.peekFirst == "<LAMBDA START>":
        endEnclosure("<LAMBDA END>")

    elif s == '[':
      startEnclosure("<VECTOR START>")

    elif s == ']':
      endEnclosure("<VECTOR END>")

    elif s == '{':
      startEnclosure("<MAP START>")

    elif s == '}':
      if stack.peekFirst == "<SET START>":
        endEnclosure("<SET END>")
      elif stack.peekFirst == "<MAP START>":
        endEnclosure("<MAP END>")

    else:
      echo s

    if strm.peekChar() == '\x00':
      break

  strm.close()