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Checks if a query returns at least one row.

Produce the empty query if the given query returns no rows. present is equivalent to WHERE EXISTS in SQL.

with is similar to filter, but allows the predicate to be a full query.

with f a = a <$ present (f a), but this form matches filter.

Like with, but with a custom membership test.

Produce the empty query if the given query returns rows. absent is equivalent to WHERE NOT EXISTS in SQL.

Filter rows where a -> Query b yields no rows.

Like without, but with a custom membership test.