英文:
What does this Scala syntax mean ("= something" after a method)?
问题
以下是翻译好的部分：
第一个例子中，该方法返回Try[List[String]]。但是 = Try 是什么？
第二个例子中，= boundary... 这是什么？
英文:
Two examples from the Scala's blog:
def canFail(input: String): Try[List[String]] = Try:
someComputation(input).flatMap: res =>
val partial = moreComputation(res)
andEvenMore(partial)
and this one:
import util.boundary, boundary.break
def sumOfRoots(numbers: List[Double]): Option[Double] = boundary:
val roots = numbers.map: n =>
println(s" * calculating square root for $n*")
if n >= 0 then Math.sqrt(n) else break(None)
Some(roots.sum)
In the first example the method returns Try[List[String]]. But what is = Try?
And in the second example, = boundary... What is it?
答案1
得分: 3
你的第一个示例可以使用大括号语法重写，如下所示，这样可能更清晰：
def canFail(input: String): Try[List[String]] = {
Try {
someComputation(input).flatMap { res =>
val partial = moreComputation(res)
andEvenMore(partial)
}
}
}
= 只是方法主体定义的开始。
在我上面的代码中，第一个大括号是不必要的。可以写成：
def canFail(input: String): Try[List[String]] = Try {
someComputation(input).flatMap { res =>
val partial = moreComputation(res)
andEvenMore(partial)
}
}
然后，如果将大括号更改为缩进语法，就会得到你的第一个代码示例。
至于 Try { ... }，它是 Try.apply { ... } 的语法糖，本身与 Try.apply({ ... }) 相同。
英文:
Your first example could be rewritten with braces syntax as the following which hopefully is more clear:
def canFail(input: String): Try[List[String]] = {
Try {
someComputation(input).flatMap { res =>
val partial = moreComputation(res)
andEvenMore(partial)
}
}
}
= is just the start of method body definition.
In my code above, the first braces are not necessary. Same could be written:
def canFail(input: String): Try[List[String]] = Try {
someComputation(input).flatMap { res =>
val partial = moreComputation(res)
andEvenMore(partial)
}
}
And then, if you changes braces for the indentation syntax, you get your first code example.
As for Try { ... }, it's syntactic sugar for Try.apply { ... }, itself the same as Try.apply({ ... }).
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