jonmmease opened a new issue #1092:
URL: https://github.com/apache/arrow-datafusion/issues/1092


   **Is your feature request related to a problem or challenge? Please describe 
what you are trying to do.**
   
   Currently, the elements of `ScalarValue::List` are restricted to be 
primitive values (e.g. `ScalarValue::iter_to_array` only supports primitive 
list element types).
   
   In particular, lists cannot be nested inside other lists.
   
   **Describe the solution you'd like**
   I would like to be able to create scalar lists of any homogeneous 
ScalarValue instances.  This would include nested lists, and lists of structs 
when ScalarValue struct support is added 
(https://github.com/apache/arrow-datafusion/issues/602).
   
   This would make it possible to represent scalar elements of Arrow arrays 
consisting of deeply nested `ListArrays` and `StructArrays`.
   
   If the general idea is acceptable, I plan to open a PR for this.  From what 
I can tell, the main thing that is needed is a fallback case in 
`ScalarValue::iter_to_array` that handles any list element type.  I would 
expect that, for performance, we would want to keep all of the existing 
specialized cases and just add a more general fallback case.
   


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