rl.nim

proc linesWithEndings(file: var TFile): seq[string] =
  var line = ""
  var buf: array[8192, char]
  var pendingCR = false
  result = newSeq[string]()
  while not file.endOfFile:
    let n = readChars(file, buf, 0, sizeof(buf))
    for i in 0.. <n:
      let ch = buf[i]
      case ch
      of '\r':
        if pendingCR:
          add(result, line)
          line.setLen(0)
        pendingCR = true
        add(line, ch)
      of '\L':
        pendingCR = false
        add(line, ch)
        add(result, line)
        line.setLen(0)
      else:
        if pendingCR:
          pendingCR = false
          add(result, line)
          line.setLen(0)
        add(line, ch)
  if len(line) > 0:
    add(result, line)