Go 1.8 Release Notes

Re:Go 1.8 Release Notes by junke on Thursday February 16, 2017 @06:50PM (#13664727)

But apart from reversing the resulting slice, how do you sort according to ">"? The current approach is more general and might be used with custom comparators. For example, it might be possible to implement the sort you have in mind with it.

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Re:Go 1.8 Release Notes by justinsaccount on Thursday February 16, 2017 @07:25PM (#13664912)

Sort could have a reverse option, but for that to work well go would need overloaded functions, or at least types that you could define an ordering on, which would let you do

  a := ReverseOrder(10)
  b := ReverseOrder(20)
  
  a < b // false

  sort.Slice(people, func(p Person) string { return ReverseOrder(p.Name) })

Comparison functions are just not very user friendly when what you really want to do is just sort naturally based on a list of fields.

  sort.Slice(people, func(p Person) (string, string, string, int) { return p.Country, P.Gender, p.Name, p.Age })

turns into a pretty messy comparison function.

Not to mention, the key func aka DSU[1] approach is much faster when the comparison function is expensive to call.. imagine something like

  sort.Slice(numbers, func(i, j int) bool { return num_factors(numbers[i]) < num_factors(numbers[j]) })

vs.

  sort.Slice(numbers, func(n int) int { return num_factors(n) })

One needs manual memoizing or caching of this function call, the other can do it internally in a much simpler manor.

[1] https://en.wikipedia.org/wiki/Schwartzian_transform

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