Spin out libfetchers into stand-alone project about nix HOT 4 OPEN

I believe it is feasible once we've narrowed down the interfaces. I wouldn't exclude the possibility that a truly different project wants to use it, although I am not aware of an example. I could see Lix or Tvix use it though. I haven't been in touch with them about this yet, but I believe the concept of reproducible fetching has a better chance of success when there's a serious project that has this as its single purpose. Specifically, it allows for more collaboration, and it is the cheapest way to have consensus about what any fetchable source should evaluate to. The alternative, competing implementations that converge on a standard, takes much more effort, and neither team seems particularly excited to work on fetchers, from what I can tell.
Without a suitable standard implementation, the only remaining choices for them are to either: give up on the concept of lazy reproducible fetching, or work on an alternate implementation that diverges (such as stabilizing the buggy 2.18 implementation in an incompatible way).

from nix.

I would say

1. Meson build
2. Use Meson subproject to build each library in own derivation
3. Move fetchTree primop and libfetchers -> libexpr to additional library (primops can be registered downstream in plugin fashion)

Step 4 would be making that additional library work as plugin, but we'll have to untangle some CLI stuff.

Future work could be be ABI stability and actually moving things out of tree, but I don't feel so urgent about that.

I do think having the core SourceAccessor stuff remaining in libutil and be used by libexpr is good, however.

from nix.

Yes, whether something is in the tree doesn't matter, it's all about strong boundaries in interfaces and ownership. Namespaces merely help with delineating responsibilities.

Side note: shouldn't libutil become a library for file system handling then?

from nix.

The use case for this is unclear to me. What other project would use libfetchers? It's extremely Nix-specific. Meanwhile it would make hacking on Nix much more painful.

from nix.