[m-users.] The new random module(s)

[Julien Fischer]

Hi Mark,

On Thu, 5 Sep 2019, Mark Brown wrote:

> On Thu, Sep 5, 2019 at 4:09 PM Julian Fondren <jfondren at minimaltype.com> wrote:
>>
>> In the permute_array/permute_list future,
>> will permute_X be added for other data structures?
>
> I wasn't planning to. Permutation is (mathematically) usually only
> defined for sets and sequences so I'm not sure what you'd be expecting
> for other library types. I suppose there could be a set permutation
> predicate that returns a randomly ordered list of the elements.
>
> In my view, the reason to put them in the random module is that they
> are more related to each other, and to the other predicates that do
> random stuff, than they are to predicates that merely work on lists or
> arrays. But no matter, I can add list.random_permutation now unless
> anyone else wants to add their opinion?

I disagree: I expect to find generic operations on lists in the list
module and generic operations on arrays in the array module.

> (array.random_permutation ought to wait until the old RNG has been
> sufficiently obsoleted. Note that I have only obsoleted the
> random.init predicate as that is sufficient to produce a warning, and
> declaring all predicates of the old implementation to be obsolete
> would only result in getting multiple warnings for essentially the
> same issue. I'll make that clearer in the docs for random.init.)

...

> So what's the choice?
>
> 1. Add random.permute_* (or whatever) now.
> 2. Add list.random_permutation and make a backwards incompatible
> change to array.random_permutation now.
> 3. Add list.random_permutation now, but wait before changing
> array.random_permutation.

I think we could avoid the namespace issues by naming the new versions
either:


     random.shuffle_list
     random.shuffle_array

or:

     list.random_shuffle
     array.randome_suffle

depending on where they end up (i.e. don't use the word permutation
or permute.)

We can always reclaim the name permutation after the old interface has
been removed.

Julien.