throwIfNot sends our error message through a function call, even if the
error condition doesn't trigger. This requires a lot of thunk allocation
that can be easily avoided.
assertMsg sends our error message through a function call, even if the
error condition doesn't trigger. This requires a lot of thunk allocation
that can be easily avoided.
Thanks to moving the existing let variable out, this should have
identical performance for non-memoised calls, and improved performance
when caching the separator.
Meaningful if these functions are partially applied. Saves 16% primops,
12% thunks, and 6% memory bytes when recursively importing all the nix
files in nixpkgs. Slightly increases memory usage when partial function
application isn't done, but I think the benefits outweigh the losses
here.
If these functions are called with partial function application (like
`lib.hasPrefix ".nix"`), then we can avoid performing the isPath check
multiple times, and only confirm it once. This gives 12% less primops
when recursively importing all nix files in nixpkgs.
- concrete types start with uppercase: Int, String, Bool, Derivation,
etc.
- type variables start with lowercase: a, b, etc.
- list:
- use `[x]` for homogeneous lists instead of `List x` or `[ x ]`
- use `List` for heterogeneous lists (not that common in `lib`)
- attr:
- use `AttrSet` for a generic attribute set type
- use `{ key1 :: Type1; key2 :: Type2; ... }` for adding signatures
for known attribute names and types
- use `{ key1 = value1; key2 = value2; ... }` for adding attributes
with known literals
- end with an ellipsis (`...`) if the set can contain unknown
attributes
- use `{ [String] :: x }` if all the attributes has the same type `x`
- prefer `Any` over `a` if the latter is not reused
Previously `lib.strings.escapeNixIdentifier "assert"` would return `"assert"`; This is wrong, `assert` is not a valid identifier unless quoted.\
This also fixes `lib.generators.toPretty`: `toPretty {} { "assert" = false; }` would previously return an invalid expression.
lib.strings.escapeC produces single‐digit hexadecimal strings for
character values ≤ 15, which results in an ambiguity. If the following
character is a hex digit, it will be interpreted as being part of the
escape sequence.
systemd, which also relies on C‐style escape sequences, does not
decode single‐digit sequences at all, even if unambiguous.
Padding the hexadecimal string with "0" avoids this problem.
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.
