不理解这段函数式编程，看不懂

Question

const TOKEN = '123'

const ROOT = '//www.baidu.com'

const root = createAPI => (...args) => {

  const result = createAPI(...args)

  return {...result, url: `${ROOT}${result.url}`}

}

const auth = createAPI => (...args) => {

  const result = createAPI(...args)

  return {

    ...result,

    headers: {...result.headers, authorization: `Bearer ${TOKEN}`},

  }

}

const projects = team => {

  return {

    url: `/api/0/teams/${team}/projects/`,

  }

}

root(auth(projects))('fe')

// 返回值如下

{

   headers: {authorization: "Bearer 123"}

   url: "//www.baidu.com/api/0/teams/fe/projects/"

}

不理解这段函数式编程，看不懂,谁能详细解释下？

### 你期待的结果是什么？实际看到的错误信息又是什么？