functional programming efficiency vs imperative

Question

I'm new to functional programming and I just ran into something and was wondering if there was a way around this.

Suppose I have

myArray = [
  { a : 1 }
  { a : 4 }
  { a : 5 }
  { a : 6 }
  { a : 7 }
  { a : 8 }
]

Let say I need to do statistical operations on this data set such as

const median = myArray[ Math.ceil( myArray.length / 2 ) ]['a'] // Math.ceil .. Side Effect?
const fiveOrMore = myArray.filter( value => value.a >= 5 )
const lessThanFive = myArray.filter( value => value.a < 5 )

Some arbitrary examples. The problem with this as of right now is that with increasing amount of statistical operations I need to do, the efficiency decreases.

With imperative style, I could do everything in ONE for loop. Is this the wrong approach to functional programming that I am taking or is it a trade off of functional programming paradigm itself?

Answer 1

这当然性能较差。性能影响是您选择的风格的权衡。

有人可能会说这没什么大不了的，因为时间复杂度是O(n)，唯一的区别是常数。我想说的是，请确保对您的应用程序进行性能测试。如果速度很慢，那么就该优化某些代码块了。

过早的优化是邪恶的。在很多情况下，命令式代码的运行速度比函数式代码更快或快得多，并且根据具体情况，您可能会也可能不会接受。

此外，还有多种技术可以提高性能。您不一定想改变风格。比如说，在某些情况下，记忆可以极大地提高函数的速度，同时保持代码的功能。跳出框框思考。