[m-rev.] for review: bugfix for io.set_environment_var/4

[Julien Fischer]

Hi Zoltan,

On Mon, 18 Apr 2016, Zoltan Somogyi wrote:

> On Mon, 18 Apr 2016 09:49:23 +1000 (AEST), Julien Fischer <jfischer at opturion.com> wrote:
>> W.r.t to Mark's change: I think we also need to add
>>
>>      :- pred have_set_environment_var is semidet.
>>
>> so that programs can test whether the unerlying platfrom supports
>> modifying the environment.
>
> I think that is a good idea, but you need a better name; that one
> suggest you are asking whether you *have* set a *particular* env var,
> not whether you *can* set *any* env var.

That predicate has no argument with which I could specify a particular
environment variable to test.  I agree the name itself is somewhat
ambiguous; I was trying to keep the naming consistent with what we use
elsewhere for similar such "feature test" predicates, e.g. have_fma/0,
have_make_temp_directory/0 etc.

Julien.