问题描述
说我有以下单个案例区分的工会:
Say I have the following single case discriminated union:
type OrderId = OrderId of string
在某些时候，我需要实际的字符串.我找到的提取方法是:
At some point I need the actual string. The way I've found for extracting it is:
let id = match orderId with OrderId x -> x
是否有更简洁的方法?
我知道我的用法是一种特殊情况，为了确保您已经涵盖了所有可能性，这场比赛很有意义，只是想知道是否有一种方法可以做到:
I understand that my use is a special case and the match makes sense in order to make sure you've covered the possibilities, just wondering if there's a way of doing something like:
let OrderId id = orderId
推荐答案
您快到了.为了使编译器将let-bound解释为模式匹配，必须加括号:
You're almost there. Parentheses are required in order that the compiler interprets a let-bound as pattern matching:
let (OrderId id) = orderId
如果orderId是函数的参数，则也可以直接在其中使用模式匹配:
If orderId is a parameter of a function, you can also use pattern matching directly there:
let extractId (OrderId id) = id
这篇关于F#中单例区分工会的简明模式匹配的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！