[m-rev.] for review: Deprecate string.append(out, out, in) mode.

[Mark Brown]

Hi Peter,

This looks fine.

On Thu, Oct 24, 2019 at 2:58 PM Peter Wang <novalazy at gmail.com> wrote:
>
> Mark pointed out that the string.append(out, out, in) mode does not
> match the forward modes. The simplest solution is to deprecate and
> eventually remove it.
>
> library/string.m:
>     Deprecate string.append(out, out, in) mode.
>
>     Add string.nondet_append/3 as its replacement.
>
>     Add more documentation.
>
> NEWS:
>     Announce changes.
>
> --------
>
> Or should the replacement be called multi_append?

The name nondet_append/3 works for me (named after the execution model
not the determinism category).

Mark