将 Scala 列表转换为元组? [英] Convert a Scala list to a tuple?
问题描述
如何将包含(例如)3 个元素的列表转换为大小为 3 的元组?
How can I convert a list with (say) 3 elements into a tuple of size 3?
例如,假设我有 val x = List(1, 2, 3)
并且我想将其转换为 (1, 2, 3)
.我该怎么做?
For example, let's say I have val x = List(1, 2, 3)
and I want to convert this into (1, 2, 3)
. How can I do this?
推荐答案
您无法以类型安全的方式执行此操作.为什么?因为通常我们直到运行时才能知道列表的长度.但是元组的长度"必须以其类型编码,因此在编译时就知道了.例如,(1,'a',true)
的类型为 (Int, Char, Boolean)
,它是 Tuple3[Int, Char,布尔]
.元组有这个限制的原因是它们需要能够处理非同构类型.
You can't do this in a typesafe way. Why? Because in general we can't know the length of a list until runtime. But the "length" of a tuple must be encoded in its type, and hence known at compile time. For example, (1,'a',true)
has the type (Int, Char, Boolean)
, which is sugar for Tuple3[Int, Char, Boolean]
. The reason tuples have this restriction is that they need to be able to handle a non-homogeneous types.
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