Thanks. You said what, but not why. When would this be used? See also https://go.dev/doc/faq#x_in_std .

I've used shuffle a few times but only ever with slices.

This feels like it should be a method on *rand.Rand though that would need to wait for some language changes.

One option to simplify using Shuffle today would be a generic version of reflect.Swapper:

package slices
func Swapper[S ~[]E, E any](slice S) func(i, j int) {
  return func(i, j int) {
    s[i], s[j] = s[j], s[i]
  })
}

But since package slices will have all those handy sorting functions the only real place that I can think of using this is with Shuffle.

@ianlancetaylor Updated the issue. I tried to submit this issue to https://github.com/golang/exp because I thought that place is for experimental things, but I saw that the golang.org/exp/slices package is about to move into std so I put the issue here.
@jimmyfrasche Thanks, I never knew that there's reflect.Swapper. But in my opinion your version of Swapper is not much related to reflect and I don't expect reflect package will have that function in near future..

This proposal has been added to the active column of the proposals project
and will now be reviewed at the weekly proposal review meetings.
— rsc for the proposal review group

It seems like a level inversion to me to have slices import rand. Perhaps rand/v2 (#61716) should be handling this instead. There is an active discussion about that over there.

This proposal is a duplicate of a previously discussed proposal, as noted above,
and there is no significant new information to justify reopening the discussion.
The issue has therefore been declined as a duplicate.
— rsc for the proposal review group