"member of " not working with nested table of dates

Question

Can someone explain why this doesn't work. The last select does not return any row. When trying the same with a table of number, it works fine.
drop table test;
drop type date_tab;
create type date_tab as table of date;
create table test(dates date_tab) nested table dates store as dates;
insert into test values (date_tab(to_date('10-jan-2007'),to_date('15-jan-2007'),to_date('15-jan-2007')));
commit;
select * from test where to_date('10-jan-2007') member of dates;
Line above should find the row, but does not return anything.

Answer 1

> With 10G Oracle said that these two engines are now sharing the same source code
Is that documented somewhere? Regarding database versions, it was 9.0.1 that claimed an integrated parser. I don't see any update for 10g.
> So in the old days one had to do a [SELECT sysdate INTO d FROM dual] to assign a function value to a PL/SQL var - as the function did not exist in PL/SQL.
Then (from Oracle 7 onwards?) these functions were also available in PL/SQL. However, the two engines did not share common code. So functions in SQL did not always behave like function in PL/SQL and vice versa.
I don't recall that limitation in PL/SQL v1 (Forms 3 to 4.5, and database v6, though I doubt many people actually used PL/SQL on the database because (1) it was separately licensed, and (2) it didn't have stored procedures) - but then it was a while ago so I could be mistaken.
I know USER, SYSDATE and others used to be implicit queries of dual (i.e. the supplied PL/SQL function was just a wrapper containing SELECT SYSDATE INTO dt FROM dual; RETURN dt;) although that's probably just confusing the issue.