Porting SICStus goal expansion to library(reif)

[triska]

As noted in the recent discussion #974, library(reif) as included in Scryer Prolog does not yet implement the goal expansion that the version for SICStus Prolog already implements. The SICStus version of library(reif) is available from:

http://www.complang.tuwien.ac.at/ulrich/Prolog-inedit/sicstus/reif.pl

In case anyone is interested in porting the goal expansion mechanism, this would be a very welcome contribution to Scryer Prolog! If Scryer needs additional features to make this work, please file them as separate issues. Thank you a lot!

[mthom]

I think all that Scryer is missing is SICStus' imported_from key of predicate_property.

[sblaplace]

Is this still a relevant and good first issue? I've looked over the code and previous commits and it seems to be the case, but I wanted to double check before giving it a shot to make sure that intents haven't changed in the mean time.

[triska]

Yes absolutely, it would be an amazing contribution, and I think a very interesting issue to look into!