[erlang-questions] Maps branch and disclaimers

Chris King <>
Wed Oct 30 15:03:59 CET 2013


On Wed, 30 Oct 2013 09:51:27 -0400, Björn-Egil Dahlberg <>  
wrote:

>
>>
>> I don't get this use case.  Why do you need syntax support for a  
>> key-value map where you don't know a priori >>what the keys and values  
>> are?  Why don't dict() and friends suffice?
>>
>> To me this is akin to iterating through a record/tuple.
>
> Actually these functions are needed, at least one is needed internally,  
> I think.
>
> It should be covered in comprehensions with Maps generators. Maps  
> generators needs next(Key, Map).
>
>  But for small Maps and record like behaviour they are not needed. =)

Mm, I think I disagree about the need for map-generators as well.   
Couldn't that be equally well served by implementing a qlc dict() source?

Well I shouldn't complain too much.  Richard O'Keefe and I both argued  
strenuously against conflating heterogeneous (record-like) and homogeneous  
(dict-like) maps months ago but I guess that ship has sailed.

I will just avoid using the dict-like features of these maps in my code,  
and hope that I am not forced to do so by the standard library or by  
popular applications.

BTW, is there a plan for a type notation for these new maps, or for how to  
get Dialyzer to usefully type-check them?
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