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### Additions and Improvements {#sec-release-24.05-lib-additions-improvements}
New functions:
-[`lib.asserts.assertEachOneOf`](https://nixos.org/manual/nixpkgs/unstable#function-library-lib.asserts.assertEachOneOf): Check that each value is one of the allowed ones.
-[`lib.attrsets.longestValidPathPrefix`](https://nixos.org/manual/nixpkgs/unstable#function-library-lib.attrsets.longestValidPathPrefix): The longest prefix of an attribute path that refers to an existing attribute in a nesting of attribute sets.
-[`lib.attrsets.mapCartesianProduct`](https://nixos.org/manual/nixpkgs/unstable#function-library-lib.attrsets.mapCartesianProduct): Apply a function to the cartesian product of attribute set value combinations.
-[`lib.lists.ifilter0`](https://nixos.org/manual/nixpkgs/unstable#function-library-lib.lists.ifilter0): Filter a list for elements that satisfy a predicate function. The predicate function is called with both the index and value for each element.
-[`lib.lists.sortOn`](https://nixos.org/manual/nixpkgs/unstable#function-library-lib.lists.sortOn): Sort a list based on the default comparison of a derived property.
-[`lib.path.hasStorePathPrefix`](https://nixos.org/manual/nixpkgs/unstable#function-library-lib.path.hasStorePathPrefix): Whether a [path](https://nixos.org/manual/nix/stable/language/values.html#type-path) has a [store path](https://nixos.org/manual/nix/stable/store/store-path.html#store-path) as a prefix.
-[`lib.filesystem.packagesFromDirectoryRecursive`](https://nixos.org/manual/nixpkgs/unstable#function-library-lib.filesystem.packagesFromDirectoryRecursive): Transform a directory tree containing package files suitable for `callPackage` into a matching nested attribute set of derivations.
-[`lib.fileset.toList`](https://nixos.org/manual/nixpkgs/unstable#function-library-lib.fileset.toList): The list of file paths contained in a given file set.
-[`lib.fileset.maybeMissing`](https://nixos.org/manual/nixpkgs/unstable#function-library-lib.fileset.maybeMissing): Create a file set from a path that may or may not exist.
-[`lib.derivations.optionalDrvAttr`](https://nixos.org/manual/nixpkgs/unstable#function-library-lib.derivations.optionalDrvAttr): Conditionally set a derivation attribute.
-[`lib.strings.makeIncludePath`](https://nixos.org/manual/nixpkgs/unstable#function-library-lib.strings.makeIncludePath): Construct an include search path (such as `C_INCLUDE_PATH`) containing the header files for a set of packages or paths.
-[`lib.derivations.lazyDerivation`](https://nixos.org/manual/nixpkgs/unstable#function-library-lib.derivations.lazyDerivation): Now supports multiple outputs with an `outputs` argument
-[`lib.gvariant`](https://nixos.org/manual/nixpkgs/unstable#sec-functions-library-gvariant): Better error message for integers and attribute set values
-[`lib.filesets.gitTracked`](https://nixos.org/manual/nixpkgs/unstable#function-library-lib.fileset.gitTracked): Now works within store paths
Misc:
- The [`lib/` directory](https://github.com/NixOS/nixpkgs/tree/release-24.05/lib) is a self-contained flake now, including a working [`lib.trivial.version`](https://nixos.org/manual/nixpkgs/unstable/#function-library-lib.trivial.version)(but note that fetching a subtree by itself is not supported in Nix yet)
-[Various minor performance improvements](https://github.com/NixOS/nixpkgs/issues?q=author%3Aadisbladis+label%3A%226.topic%3A+lib%22+created%3A%3C2024-05-31+)
Module System:
- New types:
-[`types.attrTag`](https://nixos.org/manual/nixos/unstable/#sec-option-types-sums): A tagged union type
-[`lib.options.mdDoc`](https://nixos.org/manual/nixpkgs/unstable#function-library-lib.options.mdDoc) is obsolete and now emits a warning. The core ecosystem has completely migrated to markdown, so marking markdown as markdown is redundant.
-`lib.attrsets.zipWithNames` is now a deprecated alias of [`lib.attrsets.zipAttrsWithNames`](https://nixos.org/manual/nixpkgs/unstable/#function-library-lib.attrsets.zipAttrsWithNames)
-`lib.attrsets.cartesianProductOfSets` has been renamed to [`lib.attrsets.cartesianProduct`](https://nixos.org/manual/nixpkgs/unstable/#function-library-lib.attrsets.cartesianProduct)
### Internal {#sec-release-24.05-lib-internal}
-`lib` now has [Readme for contributing](https://github.com/NixOS/nixpkgs/tree/master/lib#readme).
- Some function's documentation is now written using the [accepted doc comment syntax](https://github.com/NixOS/rfcs/pull/145).