I think that would be the case. Although, I'd imagine I'd be using 
dictionaries in this situation once I get to the point of having "Maybe" 
data in this particular example.

I am beginning to understand the value of flattening data structures in 
this context.


On Tuesday, August 2, 2016 at 12:01:01 PM UTC-7, Duane Johnson wrote:
>
> I like the syntax. It's intent is clear. However, correct me if I'm wrong, 
> but it would only work for records of records, correct? No way to deal with 
> a "Maybe Forecast", right?
>
> On Tue, Aug 2, 2016 at 12:53 PM, Ambrose Laing <[email protected] 
> <javascript:>> wrote:
>
>> Correction: what I should have written is:
>>
>> { model | primaryForecast.parameters.q = ... }
>>
>> instead of 
>>
>> { model | model.primaryForecast.parameters.q = ... }
>>
>> because the former is more consistent with the notion that the field 
>> between the | and the = must exist inside the record to the left of the |, 
>> which one of the requirements of the the current syntax.
>>
>> Again.  Wishful.
>>
>>
>> On Tuesday, August 2, 2016 at 2:44:25 PM UTC-4, Ambrose Laing wrote:
>>>
>>> When you say 
>>>
>>> { model.primaryForecast.parameters | q = ... }
>>>
>>> it seems to me that the type of the argument to the left of the '|'  is 
>>> of the same type as model.primaryForecast.parameters, so to me,
>>> this means something whose type and value is the same as 
>>> model.primaryForecast.parameters, except that q has been changed.
>>>
>>> My suggestion:
>>>
>>> { model | model.primaryForecast.parameters.q = ... }
>>>
>>> makes it clearer, I think, that what you want is of type the same as 
>>> model, but for which the sub sub sub field called q is changed.
>>> At least that is what I meant, if I didn't mention that.
>>>
>>> Then if I want something whose type is the same as a primaryForecast, 
>>> but whose q value has changed, one could write:
>>>
>>> { model.primaryForecast | parameters.q = ... }
>>>
>>> And if I want something of same type as 
>>> model.primaryForecast.parameters, but with q changed, one could write:
>>>
>>> { model.primaryForecast.parameters | q = ... }
>>>
>>> Anyway, this remains wishful, ... I am yet to grok the appeal of lenses.
>>>
>>> On Tuesday, August 2, 2016 at 12:34:24 PM UTC-4, Robin Heggelund Hansen 
>>> wrote:
>>>>
>>>> As far as I know, there is nothing against such a syntax, though I 
>>>> think the preferred syntax would be `{ model.primaryForecast.parameters | 
>>>> q 
>>>> = ...}`
>>>> It just haven't been implemented yet.
>>>>
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