That's implicit casting at work. ``` sqlite> select 2 is true; ``` is like ``` psql=# select 2::boolean is not distinct from true; ``` In the second example, `true` must be cast to integer first, so: ``` sqlite> select 2 is +true; ``` is equivalent to PostgreSQL's SQL: ``` psql=# select 2 is not distinct from +true::int; ``` And so on. So I stand by my claim above.