OT: array_accum equivalent in Oracle

WARNING: The rest of this post is for somebody who has worked with Oracle and
has migrated to PG, or for some other reason has good experience with Oracle.

I know this is off-topic for this list and should be asked in an Oracle
support-forum, but I don't have access to that, and Uncle Google didn't
return any obvious results, so here it goes...

Anybody knows if Oracle has an equivalent of PG's array_accum or
ARRAY(subselect) construct?

I need a way to accomplish this in Oracle:
select ARRAY(select t.id from table t where t.user_id = u.id) as
id_array, ....

Any hints on where to look in Oracle-docs are welcome.

--
Andreas Joseph Krogh <andreak(at)officenet(dot)no>
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