I guess I haven't explained well what I am looking for.

I want to set values deep inside a json structure, no matter if the full structure already exists.

Go into "outer", if it doesn't exist make it an empty object. 

From there go into "inner" and set it to "new-value".

The first part should be arbitrarily deep.

Best

Jan

Benjamin Edwards <edwards.benj@gmail.com> schrieb am Di., 20. Dez. 2016 um 13:42 Uhr:

If the desired function doesn't inspect the input then why not just use const <<thing you want>> ?

As to the lenses part: If you use a prism and it doesn't match, then it's a noop.

On Tue, 20 Dec 2016 at 09:38 Jan von Löwenstein <jan.loewenstein@gmail.com> wrote:

Hi,

I want to have code that produces the following result no matter if input A or B was given:

Result:

{

  "outer" : {

                  "inner" : "new-value"

                }

}

A: 

{

  "outer" : {

                  "inner" : "old-value"

                }

}

B:

{}

`json & key "outer"._Object.key "inner" .~ "new-value"` didn't work.

Is what I want even possible with lenses?

Best

Jan

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