[Nix-dev] Concatenation of values

[Shea Levy]

Hi Arseniy,

The ordering of the concatenation is by default unspecified. You can 
put constraints on it with 'mkOrder', see 
https://github.com/NixOS/nixpkgs/blob/a2aab3a224939cc7c24e88984c5f5ab169aee271/lib/modules.nix#L464-L470 
for the details. So you can for example have the line that sets 
'sessionCommands = "new lines of cfg";' instead set 'sessionCommands = 
mkAfter "new lines of cfg";'

~Shea

On 2015-11-21 19:09, Arseniy Seroka wrote:
> Hello!
> For example we have 
> `services.xserver.displayManager.sessionCommands`.
> If we enable slim then we have some lines added to it.
> If we add something there in our `configuration.nix` then it appears
> that our value is added before the value added by slim's config.
> So the question is how does this mechanism works (concatenation of 
> values)
> and how I can tell nix to do smth like "${old} + new lines of cfg"?
>
> --
>
> Sincerely,
> Arseniy Seroka
>
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