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https://issues.apache.org/jira/browse/TINKERPOP-968?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15126856#comment-15126856
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pieter martin commented on TINKERPOP-968:
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Ok great,

The {{coalesce}} indeed does what I am looking for.
All that remains is whether its a good idea to add the {{optional}} keyword 
anyways and compile that to a {{coalesce}}

I would argue that it is worth it as I certainly have read the {{coalesce}} 
docs before without understanding it. Considering the TinkerPop crew also 
forgot that {{coalesce}} together with {{identity}}  is equivalent to 
{{optional}} perhaps it would make life easier if {{optional}} gets first class 
status?
Its also somewhat shorter as there would be no need for the {{identity}} 
traversal.

Thanks
Pieter

> Add first class support for an optional traversal
> -------------------------------------------------
>
>                 Key: TINKERPOP-968
>                 URL: https://issues.apache.org/jira/browse/TINKERPOP-968
>             Project: TinkerPop
>          Issue Type: Improvement
>          Components: process
>    Affects Versions: 3.1.0-incubating
>            Reporter: pieter martin
>
> Both SparQL and Cypher use the "Optional" keyword to indicate an optional 
> traversal. SQL uses the "left join".
> Gremlin has no first class support for an optional traversal. It can be 
> achieved with the choose step but it is verbose, unintuitive and not what the 
> choose step is intended for.
> The benefits of optional traversals are many. In particular it makes it 
> trivial to load complete subgraphs/trees with one easy to read intuitive 
> gremlin statement.



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