f# - 有没有办法在 F# 中封装模式？

Question

有没有办法在 F# 中封装模式？

例如，而不是写这个......

let stringToMatch = "example1"

match stringToMatch with
| "example1" | "example2" | "example3" -> ...
| "example4" | "example5" | "example6" -> ...
| _ -> ...

有什么方法可以沿着这些方向完成某些事情......

let match1to3 = | "example1" | "example2" | "example3"
let match4to6 = | "example4" | "example5" | "example6"

match stringToMatch with
| match1to3 -> ...
| match4to6 -> ...
| _ -> ...

Answer 1

你可以用 Active Patterns 做到这一点:

let (|Match1to3|_|) text = 
    match text with
    | "example1" | "example2" | "example3" -> Some text
    | _ -> None

let (|Match4to6|_|) text = 
    match text with
    | "example4" | "example5" | "example6" -> Some text
    | _ -> None

match stringToMatch with
| Match1to3 text -> ....
| Match4to6 text -> ....
| _ -> ...