simulate a FULL OUTER JOIN in edgeql

full_outer_join_1.edgeql

# Do a FULL OUTER JOIN on User.name[0] = Card.name[0]
# (the seed computable is to demonstrate that it works with computed data)
WITH
    L := User { seed := random() },
    R := Card,
    joined := DISTINCT {
        (FOR l IN {L} UNION ([l.id], [(SELECT R FILTER l.name[0] = R.name[0]).id] ?? <array<uuid>>[])),
        (FOR r IN {R} UNION (([(SELECT L FILTER L.name[0] = r.name[0]).id] ?? <array<uuid>>[]), [r.id])),
    },
FOR row in {joined} UNION (
    {
        l := (SELECT L { name, seed } FILTER .id = array_unpack(row.0) LIMIT 1),
        r := (SELECT R { name, cost, element } FILTER .id = array_unpack(row.1) LIMIT 1),
    }
);