我是新手我已經在此鏈接中下載了一些源 https://github.com/the-road-to-learn-react/react-redux-example 我在文件 src/app.js 第 4 行中有一些問題const applyFilter = searchTerm => article =>  article.title.toLowerCase().includes(searchTerm.toLowerCase());為什么這不能與const applyFilter = searchTerm => article =>{  article.title.toLowerCase().includes(searchTerm.toLowerCase());} 或者const applyFilter = searchTerm => {article =>  article.title.toLowerCase().includes(searchTerm.toLowerCase());}并在第 14 行調用函數時articles.filter(applyFilter(searchTerm))const applyFilter = searchTerm => article =>  article.title.toLowerCase().includes(searchTerm.toLowerCase());這在我看來是在箭頭函數內調用箭頭函數？他們怎么能把 var 'article' 放進去？