How to select one element from a group?

I have a table t with columns foo and bar:

foo bar
a   x
a   y
b   z

I want to write something like

select foo, count(*) as num, SOMETHING(bar) from t group by foo;

and get

foo num bar
a   2   x    <--- or y, I don't care
b   1   z

I.e., SOMETHING should select an arbitrary value that appeared in a group (first, last, random - I don't care).

Is there a way to do it in sqlite3?