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.
The deprecation warnings in lib were wildly inconsistent. Different
formulations were used in different places for the same meaning. Some warnings
used builtins.trace instead of lib.warn, which prevents silencing; one even
only had a comment instead. Make everything more uniform.
A more efficient sort in some cases, and often convenient.
This exposes `lib.lists.sortOn` immediately on `lib`, because it is
a sibling of `sort`, which is already present there.
Omitting it would lead to more confusion, and worse outcomes.
There's no confusion about the types `sort` or `sortOn` operate on.
Haskell agrees about the type for `sortOn`, and it is in its `base`.
To maintain backwards compatibility, this can't be changed in the Nix language.
We can however ensure that the version Nixpkgs has the more intuitive behavior.
There are a number of different syntaxes used for attrset type
signatures in our doc strings, this change standardises upon one that
uses :: for specifying attribute type, and ; terminators to be
consistent with nix syntax. There are no bugs in the functions
themselves, just that different syntaxes may confuse new users.
The current implementation of `mutuallyExclusive` builds a new list with
length subtracted by one on every recursive call which is expensive. When
b is empty, the function still traverses a in its entirety before returning
a result.
The new implementation uses `any` to check if each element of list b is in
list a using `elem`. This maintains short circuiting when list a or b is empty
and has a worst case time complexity of O(nm).
Nix can perform static scope checking, but whenever code is inside
a `with` expression, the analysis breaks down, because it can't
know statically what's in the attribute set whose attributes were
brought into scope. In those cases, Nix has to assume that
everything works out.
Except it doesnt. Removing `with` from lib/ revealed an undefined
variable in an error message.
If that doesn't convince you that we're better off without `with`,
I can tell you that this PR results in a 3% evaluation performance
improvement because Nix can look up local variables by index.
This adds up with applications like the module system.
Furthermore, removing `with` makes the binding site of each
variable obvious, which helps with comprehension.
