prompt.lua

local uv = require 'uv'

local buffer = ""
local waiting = {}

process.stdin:on("data", function(data)
  if not data then return end

  buffer = buffer .. data

  local n = string.find(buffer, '\n', 1, true)
  while n and waiting[1] do
    local data = string.sub(buffer, 1, n - 1)
    buffer = buffer:sub(n + 1)

    assert(coroutine.resume(table.remove(waiting, 1), data)

    n = string.find(buffer, '\n', 1, true)
  end

  if not waiting[1] then
    process.stdin:pause()
  end
end)

return function(prompt)
  if prompt then
    process.stdout:write(prompt)
  end

  local n = string.find(buffer, '\n', 1, true)
  if n then
    local data = string.sub(buffer, 1, n - 1)
    buffer = buffer:sub(n + 1)

    return data
  end

  process.stdin:resume()

  table.insert(waiting, coroutine.running())
  return coroutine.yield()
end