Build an index out of a bunch of Packages.

If there are duplicates, later ones mask earlier ones.

Merge two indexes.

Packages from the second mask packages of the same exact name (case-sensitively) from the first.

Inserts a single package into the index.

This is equivalent to (but slightly quicker than) using mappend or merge with a singleton index.

Does a lookup by package id (name & version).

Since multiple package DBs mask each other case-sensitively by package name, then we get back at most one package.

Does a case-sensitive search by package name and a range of versions.

We get back any number of versions of the specified package name, all satisfying the version range constraint.

Does a case-insensitive search by package name.

If there is only one package that compares case-insentiviely to this name then the search is unambiguous and we get back all versions of that package. If several match case-insentiviely but one matches exactly then it is also unambiguous.

If however several match case-insentiviely and none match exactly then we have an ambiguous result, and we get back all the versions of all the packages. The list of ambiguous results is split by exact package name. So it is a non-empty list of non-empty lists.

Does a case-insensitive substring search by package name.

That is, all packages that contain the given string in their name.

Get all the packages from the index.

They are grouped by package name, case-sensitively.

All packages that have dependencies that are not in the index.

Returns such packages along with the dependencies that they're missing.

Tries to take the transative closure of the package dependencies.

If the transative closure is complete then it returns that subset of the index. Otherwise it returns the broken packages as in brokenPackages.

• Note that if the result is Right [] it is because at least one of the original given PackageIdentifiers do not occur in the index.

Takes the transative closure of the packages reverse dependencies.

• The given PackageIdentifiers must be in the index.

Given a package index where we assume we want to use all the packages (use dependencyClosure if you need to get such a index subset) find out if the dependencies within it use consistent versions of each package. Return all cases where multiple packages depend on different versions of some other package.

Each element in the result is a package name along with the packages that depend on it and the versions they require. These are guaranteed to be distinct.

Find if there are any cycles in the dependency graph. If there are no cycles the result is [].

This actually computes the strongly connected components. So it gives us a list of groups of packages where within each group they all depend on each other, directly or indirectly.

Builds a graph of the package dependencies.

Dependencies on other packages that are in the index are discarded. You can check if there are any such dependencies with brokenPackages.