Stream a text file line by line with Nim streams

import std/[streams, strutils]

proc eachLine(path: string; onLine: proc(line: string) {.closure.}) =
  var fs = newFileStream(path, fmRead)
  if fs == nil:
    raise newException(IOError, "cannot open " & path)
  defer: fs.close()
  var line = ""
  while fs.readLine(line):
    onLine(line.strip(leading = false, chars = {'\r'}))

var count = 0
eachLine("data.txt", proc(line: string) = inc count)
echo count