我怎样才能重构出所需要的其他条款？ [英] How can I refactor out the required else clause?

问题描述

我有一个看起来有点像这样一个C＃方法：

I have a C# method that looks a bit like this:

bool Eval() {
  // do some work
  if (conditionA) {
     // do some work
     if (conditionB) {
       // do some work
       if (conditionC) {
         // do some work
         return true;
       }
     }
  }
  return false;
}

在F＃这结束了，因为强制else分支的看着颇有几分丑陋

In F# this ends up looking quite a bit uglier because of the mandatory else branches:

let eval() =
  // do some work
  if conditionA then
    // do some work
    if conditionB then
      // do some work
      if conditionC then
        // do some work
        true
      else
        false
    else
      false
  else
    false

什么是F＃中写这篇的更清洁的方式？

What would be a cleaner way of writing this in F#?

推荐答案

那么，既然做一些工作已是势在必行（大概），那么我认为

Well, since 'do some work' is already imperative (presumably), then I think that

let eval() =
    let mutable result = false
    ... // ifs
        result <- true
    ... // no more elses
    result

较短合理。 （换句话说，其他仅供如果返回值的表达式强制性的;因为你正在做的工作势在必行，使用不需要其他）

is shorter and reasonable. (In other words, else is only mandatory for if expressions that return values; since you're doing imperative work, use if statements that don't need an else.)

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