[Nix-dev] Fwd: Re: Displaying package parameters

[Fabian Schmitthenner]

huh? what's the problem?

To be clear, when clicking on a package, some parameters will be shown,
e. g. asciidoc, qtbase.base have quite some parameters.
For some packages, "error" "some error happened" is displayed, that
means that the parameters couldn't be determined because callPackage
wasn't used in the normal way. Also, currently packages that don't
succeed are currently shown and the error is displayed in the long
description.

On 02/29/2016 04:14 AM, Roger Qiu wrote:
> Demo doesn't seem to be working atm.
> 
> On 29/02/2016 2:59 PM, Fabian Schmitthenner wrote:
>> Hi!
>>
>> I just wanted to share that I tried displaying package parameters on the
>> nixos homepage and the current result can be seen here:
>> http://schmitthenner.eu/nixos-homepage/nixos/packages.html.
>>
>> When you click on a package, you hopefully see its parameter. This uses
>> a heruristic to try to figure out which parameters are packages (and
>> thus not displayed) and which are not (and thus displayed) that goes
>> roughly as follows:
>>
>> - If the parameter is instantiated - either implicitly or explicitly -
>> by callPackage, we look at the value and if it's a derivation, or a list
>> or attrset set of derivations, or a function it's not displayed
>> - Otherwise, it's displayed
>>
>> I think there was a discussion about this a short while ago, but I
>> couldn't find it.
>>
>> Please let me know what you think and if we might want a (more elaborate
>> version, e. g. also displaying the value of default arguments that
>> aren't changed by callPackage, which requires an other change to nix
>> because this info is currently not available, we only know if the
>> argument is optional or not afaik) of this on our official website.
>>
>> Source code can be found on
>> https://github.com/NixOS/nixos-homepage/compare/master...fkz:master
>> Technically, I patched nixpkgs customization, so we not only get the
>> override... functions, but also the original parameters and the original
>> function.
>> Furthermore, this uses a patched version of nix which allows catching
>> errors inside nix (added a primop __catch) that also seems useful more
>> generally (when polished) (see
>> https://github.com/fkz/nix/tree/catch-throw).
>>
>> Fabian
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>