Re: term_expansion/2 with DCG clauses

On Wed, Aug 14, 2013 at 3:24 AM, Jan Wielemaker <[email protected]> wrote:

> On 08/14/2013 04:28 AM, Richard A. O'Keefe wrote:
>
>> If I recall correctly, DCG expansion was done *before* user expansion.
>> With there being no goal_expansion in those days, this was important if
>> you wanted users to be able to plug their own goal_expansion code in and
>> have it apply to the result of DCG expansion.
>> Further, DCG expansion was available as library code, so if you wanted it,
>> you could very easily call it yourself.
>>
>
> So not doing DCG expansion if user expansion is involved seems out of
> date. The idea to chain `translation packages' is also implemented in
> Ciao and ECLiPSe (and Logtalk?), although the way the packages are
> specified there is much more fine-grained.
>

Is there a reason why macro expansions are not all iterated until a fixed
point is reached?  expand_goal/2 behaves that way and I find it quite
practical.  It seems to eliminate some of the problems we get from doing
one kind of expansion always before another.

-- 
Michael
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