[m-rev.] for review: add io.write_array/[56] and array2d.is_empty/1

[Julien Fischer]

On Fri, 18 Mar 2016, Zoltan Somogyi wrote:

>
>
> On Fri, 18 Mar 2016 12:03:26 +1100 (AEDT), Julien Fischer <jfischer at opturion.com> wrote:
>> +do_write_array(Array, Separator, OutputPred, I, Hi, !IO) :-
>> +    ( if I =< Hi then
>> +        array.unsafe_lookup(Array, I, E),
>> +        OutputPred(E, !IO),
>> +        ( if I < Hi
>> +        then io.write_string(Separator, !IO)
>> +        else true
>> +        ),
>> +        do_write_array(Array, Separator, OutputPred, I + 1, Hi, !IO)
>> +    else
>> +        true
>> +    ).
>
> We want to write N elements but only N-1 separators.
> It would be better to write the first element in write_array,
> and to always write a separator/element pair in do_write_array.
> This would allow us to do only one test in each loop
> iteration.

Done -- thanks for the review.

Julien.