feat: show signature(s)

[caspervk]

Adds a checkmark to identify whether or not packages have signatures.

This is useful for inspecting which packages are available in caches and which ones have to be built locally. Debugging cache-misses in this way may be misleading if packages have preferLocalBuild = true. Future work could include visualising this too.

[caspervk]

This probably needs better documentation, and I also don't know anything about Haskell. Consider this a proposal for discussion rather than a production-ready PR.

[utdemir]

Code-wise it looks production ready to me!

I'm just thinking about the documentation, as you suggested. As it's hard to understand what that checkbox means from the UI.

So it's probably worth just adding a note to the bottom panel. I'm happy to do that if you are not familiar with Haskell.

However I'm not as familiar with the signatures - what would be the correct wording to put there? Is it just a phrase like "Signature available", or is it more like "3 signatures available" or like "signed by X" or something?

[caspervk]

I already have a Signatures: ✓ in the bottom panel to link the checkmark indicator to an actual word, but it was intended more as a placeholder until I could get your feedback. For my personal usecase -- identifying cache-misses -- describing the checkmark as a cache miss/hit would make more sense, but it's probably better to stay closer to the Nix data structure for those who are actually familiar with the internals of Nix.

Your "signed by" idea is really good. The checkmark enables quickly identifying cache-misses in the tree, and the Signed by: cache.nixos.org in the bottom panel is a hint that signature => cache hit, while potentially also adding additional useful information for Nix experts. I tried to add it, but it needs some cleanup 😬

Please feel free to make any changes and improvements (such as reimplementing all of it in idiomatic Haskell) as you see fit!

[utdemir]

Thanks for the PR and the followups! I just moved Signature: to a new line, and refactored the parsing part a bit, and pushed it: 42849b0 (I couldn't push it to your branch so I kept your commit separate and added my changes on top so this PR shows up as merged).

I'll fix a couple of things and cut a new release, hopefully today :).