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From Charles Joynt <Charles.Jo...@gresearch.co.uk>
Subject RE: [DISCUSS] Treating null as false in boolean expressions in Stellar
Date Tue, 19 Jun 2018 11:57:50 GMT
I'd welcome both of these on the grounds that they'll make life easier writing short(er) Stellar
code AND deciphering what someone else has written.

-----Original Message-----
From: Casey Stella [mailto:cestella@gmail.com] 
Sent: 16 June 2018 18:33
To: dev@metron.apache.org
Subject: Re: [DISCUSS] Treating null as false in boolean expressions in Stellar

I created a PR for the empty collection falseyness as well:
https://github.com/apache/metron/pull/1064 so we can choose either of them if we so desire.

On Sat, Jun 16, 2018 at 1:10 PM Casey Stella <cestella@gmail.com> wrote:

> I created a PR for this functionality, in case we decided for it:
> https://github.com/apache/metron/pull/1063
>
> Also, while we're talking, perhaps we should treat empty lists as 
> false as well, like javascript and python.
> So, for instance, if [] then 'blah' else 'foo' would return foo.
>
> Thoughts?
>
> On Sat, Jun 16, 2018 at 10:17 AM Casey Stella <cestella@gmail.com> wrote:
>
>> Right now, because fields may not exist, users can have an awkward time.
>> For instance, checking for is_alert, you end up having to preface 
>> checks with exists(is_alert).
>>
>> For instance, in one of our use-cases:
>> https://github.com/apache/metron/tree/master/use-cases/geographic_log
>> in_outliers
>> we use
>>
>> "is_alert := exists(is_alert) && is_alert", "is_alert := is_alert || 
>> (geo_outlier != null && geo_outlier == true)",
>>
>>  instead of :
>>
>> "is_alert := is_alert || geo_outlier == true",
>>
>> I suggest that we adopt a convention from javascript whereby we 
>> assume a field not existing or being null should act as false in 
>> boolean expressions.  This will simplify stellar's use and hopefully 
>> result in less awkwardness.
>>
>> Thoughts?
>>
>

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