presto-main/src/main/java/io/prestosql/type/TinyintOperators.java/TinyintOperators/castToBoolean
class TinyintOperators:    @ScalarOperator(CAST)
    @SqlType(StandardTypes.BOOLEAN)
    public static boolean castToBoolean(@SqlType(StandardTypes.TINYINT) long value)
    {
        return value != 0;
    }