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]> 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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