只需解析命令行参数即可

Question

我想使用以下代码来限制只有一个参数.但是,我收到以下错误first :: NIL？

Error   1   This expression was expected to have type
    string []    
but here has type
    'a list 

[<EntryPoint>]
let main argv = 

    match argv with 
    | first :: NIL -> 
         .... do something with first
    | _ -> failwith "Must have only one argument."

Answer 1

命令行参数作为数组传递,而不是列表.

如果您只想要一个参数,请执行以下操作:

match argv with 
| [|first|] -> 
     // .... do something with first
| _ -> failwith "Must have only one argument."