Are `choose` and `shuffle` guaranteed to be the same across versions?

[quadrupleslap]

If not, what's the alternative?

[dhardy]

At the moment, they should be across patch versions but not necessarily the next minor series. We're still pre-1.0 and haven't seen much need to focus on value-stability yet, though see notes in the doc/ subdir.

Post 1.0 these will probably be made value-stable. If you really need the same result each time now, I don't think you have any choice but to implement the algorithms yourself (or use the current Rand, but check compatibility when upgrading and if necessary use a copy of the old algorithm).

[dhardy]

I believe this is now covered by the portability section in the book, albeit implicitly — these functions should be portable and deterministic.

Also FYI we currently have no plans to adjust these algorithms, so there's a good change they will remain stable post 1.0.