It's very easy to resort to lib.take + lib.drop to accomplish this, but it's not obvious that it actually performs quite badly.
Replacing an item in a list should be a relative common operation.
The before and after of
nix-instantiate --eval -A lib.teams --strict --json | jq 'walk(if type == "array" then sort else . end)'
has been ensured to be negligible, only consisting of minor team
shortName and scope differences
- `lib.attrsets.cartesianProductOfSets` was deprecated in 228621e42d
- `lib.attrsets.zip` was deprecated in fcbc4fe9ff (2013!)
- `lib.attrsets.zipWithNames` was deprecated in 00127bef3f (2009!)
The time has come.
A Cross Index, short for Cross Platform Pair Index, is the essential
shape of a splice, without the invoking the more mind bending concept
of adding variations of for these 6 pairings to an existing thing so
that it can be switched out for something else.
So the purpose of a Cross Index is to contain the result of `f`\
(which may be reified in code, or just an abstract concept):
- f "build" "build"
- f "build" "host"
- ...
Splicing on the other hand refers not just to these six variants, but
to the idea of tacking them onto one of the variants. (hostTarget,
I believe)
Cross Indexes are a necessity for making cross compilation work, but
splicing is more than necessary.
This patch adds `lib.repoRevToName` function that generalizes away most of the
code used for derivation name generation by `fetch*` functions (`fetchzip`,
`fetchFromGitHub`, etc, except those which are delayed until latter commits
for mass-rebuild reasons).
It's first argument controls how the resulting name will look (see below).
Since `lib` has no equivalent of Nixpkgs' `config`, this patch adds
`config.fetchedSourceNameDefault` option to Nixpkgs and then re-exposes
`lib.repoRevToName config.fetchedSourceNameDefault` expression as
`pkgs.repoRevToNameMaybe` which is then used in `fetch*` derivations.
The result is that different values of `config.fetchedSourceNameDefault` now
control how the `src` derivations produced by `fetch*` functions are to be
named, e.g.:
- `fetchedSourceNameDefault = "source"` (the default):
```
$ nix-instantiate -A fuse.src
/nix/store/<hash>-source.drv
```
- `fetchedSourceNameDefault = "versioned"`:
```
$ nix-instantiate -A fuse.src
/nix/store/<hash>-libfuse-2.9.9-source.drv
```
- `fetchedSourceNameDefault = "full"`:
```
$ nix-instantiate -A fuse.src
/nix/store/<hash>-libfuse-2.9.9-github-source.drv
```
See the documentation of `config.fetchedSourceNameDefault` for more info.
Format all Nix files using the officially approved formatter,
making the CI check introduced in the previous commit succeed:
nix-build ci -A fmt.check
This is the next step of the of the [implementation](https://github.com/NixOS/nixfmt/issues/153)
of the accepted [RFC 166](https://github.com/NixOS/rfcs/pull/166).
This commit will lead to merge conflicts for a number of PRs,
up to an estimated ~1100 (~33%) among the PRs with activity in the past 2
months, but that should be lower than what it would be without the previous
[partial treewide format](https://github.com/NixOS/nixpkgs/pull/322537).
Merge conflicts caused by this commit can now automatically be resolved while rebasing using the
[auto-rebase script](8616af08d9/maintainers/scripts/auto-rebase).
If you run into any problems regarding any of this, please reach out to the
[formatting team](https://nixos.org/community/teams/formatting/) by
pinging @NixOS/nix-formatting.
It creates interoperability issues that can not be reconciled by
`lib` or maintainers of projects that use the Nixpkgs library.
Occasionally, end users may be able to solve the problems they run
into, but most are not prepared to deal with this set of problems,
nor should they be.
Typical conflict:
- User wants to propagate their own lib, because it has some function
they like to use throughout their projects
- Project maintainer requires the project's lib to be used
No sane language uses a single namespace for combining all the things.
(Arguably not even C with its extensive use of prefixing)
Meanwhile, in Nix, all symbols are first class variables. We don't even
have the concept of a global top-level namespace to pour everything into.
With `lib` you can try to approximate that, I get the appeal of its
apparent simplicity, but since `lib` can't be global, we just don't even
get that apparent simplicity.
I apologize for not offering concrete solutions to this in the text.
The manuals are limited to reference documentation.
Alternatives - of which we have multiple - are best provided in
task-oriented documentation, e.g. nix.dev.
