[Nix-dev] Re: Attribute selection with default

[Ludovic Courtès]

Hi,

Eelco Dolstra <e.dolstra at tudelft.nl>
writes:

> Nicolas Pierron wrote:

>>> The next question is how to handle multiple level like `attrByPath
>>> ["a" "b" "c"] default as', one possible way is to attribute selections
>>> inside the name of the selected attribute.
>>>
>>> as.{a.b.c ? default}
>
> I don't find this more intuitive than "as.a.b.c or default".

IIUC Nicolas’ proposal is more flexible than ‘or’, because
“as.a.b.c or default” could mean any one of:

  - as.{a.b.c ? default}
  - as.a.{b.c ? default}
  - as.a.b.{c ? default}

I.e., it provides finer control.

Thanks,
Ludo’.