@ScalarOperator(CAST)
    @LiteralParameters("x")
    @SqlType("varchar(x)")
    public static Slice castToVarchar(@SqlType(StandardTypes.BOOLEAN) boolean value)
    {
        return value ? TRUE : FALSE;
    }
@Test
    public void testCastToVarchar()
    {
        assertFunction("cast(true as varchar)", VARCHAR, "true");
        assertFunction("cast(false as varchar)", VARCHAR, "false");
    }