F＃：尝试在VS Code上运行简单的F＃程序时出现路径错误

Question

我刚刚在另一台笔记本电脑上安装了Visual Studio Code，然后继续获取Ionide-fsharp扩展名。然后，我尝试运行以下简单代码：

open System

let rec factorial n =
    if n = 0
    then 1
    else n * factorial (n - 1)

factorial 5

但是随后出现此错误，我似乎无法解决它：

 open: the term 'open' is not recognized as the name of a cmdlet,
 function, script file, or operable program. Check the spelling on the name, 
 of if a path was included, verify that the path is correct and try again.

然后它继续向我扔很多废话，然后对我以后编写的每一行代码重复上述错误。请帮忙。