Copyright | (c) David Himmelstrup 2005 Bjorn Bringert 2007 Duncan Coutts 2008-2009 |
---|---|

Maintainer | cabal-devel@haskell.org |

Portability | portable |

Safe Haskell | None |

Language | Haskell2010 |

An index of packages whose primary key is `UnitId`

. Public libraries
are additionally indexed by `PackageName`

and `Version`

.
Technically, these are an index of *units* (so we should eventually
rename it to `UnitIndex`

); but in the absence of internal libraries
or Backpack each unit is equivalent to a package.

While `PackageIndex`

is parametric over what it actually records,
it is in fact only ever instantiated with a single element:
The `InstalledPackageIndex`

(defined here) contains a graph of
`InstalledPackageInfo`

s representing the packages in a
package database stack. It is used in a variety of ways:

- The primary use to let Cabal access the same installed
package database which is used by GHC during compilation.
For example, this data structure is used by 'ghc-pkg'
and
`Cabal`

to do consistency checks on the database (are the references closed). - Given a set of dependencies, we can compute the transitive closure of dependencies. This is to check if the versions of packages are consistent, and also needed by multiple tools (Haddock must be explicitly told about the every transitive package to do cross-package linking; preprocessors must know about the include paths of all transitive dependencies.)

This `PackageIndex`

is NOT to be confused with
`PackageIndex`

, which indexes packages only by
`PackageName`

(this makes it suitable for indexing source packages,
for which we don't know `UnitId`

s.)

## Synopsis

- type InstalledPackageIndex = PackageIndex InstalledPackageInfo
- data PackageIndex a
- fromList :: [InstalledPackageInfo] -> InstalledPackageIndex
- merge :: InstalledPackageIndex -> InstalledPackageIndex -> InstalledPackageIndex
- insert :: InstalledPackageInfo -> InstalledPackageIndex -> InstalledPackageIndex
- deleteUnitId :: UnitId -> InstalledPackageIndex -> InstalledPackageIndex
- deleteSourcePackageId :: PackageId -> InstalledPackageIndex -> InstalledPackageIndex
- deletePackageName :: PackageName -> InstalledPackageIndex -> InstalledPackageIndex
- lookupUnitId :: PackageIndex a -> UnitId -> Maybe a
- lookupComponentId :: PackageIndex a -> ComponentId -> Maybe a
- lookupSourcePackageId :: PackageIndex a -> PackageId -> [a]
- lookupPackageId :: PackageIndex a -> PackageId -> Maybe a
- lookupPackageName :: PackageIndex a -> PackageName -> [(Version, [a])]
- lookupDependency :: InstalledPackageIndex -> PackageName -> VersionRange -> [(Version, [InstalledPackageInfo])]
- lookupInternalDependency :: InstalledPackageIndex -> PackageName -> VersionRange -> LibraryName -> [(Version, [InstalledPackageInfo])]
- searchByName :: PackageIndex a -> String -> SearchResult [a]
- data SearchResult a
- = None
- | Unambiguous a
- | Ambiguous [a]

- searchByNameSubstring :: PackageIndex a -> String -> [a]
- allPackages :: PackageIndex a -> [a]
- allPackagesByName :: PackageIndex a -> [(PackageName, [a])]
- allPackagesBySourcePackageId :: HasUnitId a => PackageIndex a -> [(PackageId, [a])]
- allPackagesBySourcePackageIdAndLibName :: HasUnitId a => PackageIndex a -> [((PackageId, LibraryName), [a])]
- brokenPackages :: PackageInstalled a => PackageIndex a -> [(a, [UnitId])]
- dependencyClosure :: InstalledPackageIndex -> [UnitId] -> Either InstalledPackageIndex [(InstalledPackageInfo, [UnitId])]
- reverseDependencyClosure :: PackageInstalled a => PackageIndex a -> [UnitId] -> [a]
- topologicalOrder :: PackageInstalled a => PackageIndex a -> [a]
- reverseTopologicalOrder :: PackageInstalled a => PackageIndex a -> [a]
- dependencyInconsistencies :: InstalledPackageIndex -> [(DepUniqueKey, [(UnitId, [InstalledPackageInfo])])]
- dependencyCycles :: PackageInstalled a => PackageIndex a -> [[a]]
- dependencyGraph :: PackageInstalled a => PackageIndex a -> (Graph, Vertex -> a, UnitId -> Maybe Vertex)
- moduleNameIndex :: InstalledPackageIndex -> Map ModuleName [InstalledPackageInfo]

# Package index data type

type InstalledPackageIndex = PackageIndex InstalledPackageInfo #

The default package index which contains `InstalledPackageInfo`

. Normally
use this.

data PackageIndex a #

The collection of information about packages from one or more `PackageDB`

s.
These packages generally should have an instance of `PackageInstalled`

Packages are uniquely identified in by their `UnitId`

, they can
also be efficiently looked up by package name or by name and version.

## Instances

# Creating an index

fromList :: [InstalledPackageInfo] -> InstalledPackageIndex #

Build an index out of a bunch of packages.

If there are duplicates by `UnitId`

then later ones mask earlier
ones.

# Updates

merge :: InstalledPackageIndex -> InstalledPackageIndex -> InstalledPackageIndex #

Merge two indexes.

Packages from the second mask packages from the first if they have the exact
same `UnitId`

.

For packages with the same source `PackageId`

, packages from the second are
"preferred" over those from the first. Being preferred means they are top
result when we do a lookup by source `PackageId`

. This is the mechanism we
use to prefer user packages over global packages.

deleteUnitId :: UnitId -> InstalledPackageIndex -> InstalledPackageIndex #

Removes a single installed package from the index.

deleteSourcePackageId :: PackageId -> InstalledPackageIndex -> InstalledPackageIndex #

Removes all packages with this source `PackageId`

from the index.

deletePackageName :: PackageName -> InstalledPackageIndex -> InstalledPackageIndex #

Removes all packages with this (case-sensitive) name from the index.

NB: Does NOT delete internal libraries from this package.

# Queries

## Precise lookups

lookupUnitId :: PackageIndex a -> UnitId -> Maybe a #

Does a lookup by unit identifier.

Since multiple package DBs mask each other by `UnitId`

,
then we get back at most one package.

lookupComponentId :: PackageIndex a -> ComponentId -> Maybe a #

Does a lookup by component identifier. In the absence
of Backpack, this is just a `lookupUnitId`

.

lookupSourcePackageId :: PackageIndex a -> PackageId -> [a] #

lookupPackageId :: PackageIndex a -> PackageId -> Maybe a #

Convenient alias of `lookupSourcePackageId`

, but assuming only
one package per package ID.

lookupPackageName :: PackageIndex a -> PackageName -> [(Version, [a])] #

Does a lookup by source package name.

lookupDependency :: InstalledPackageIndex -> PackageName -> VersionRange -> [(Version, [InstalledPackageInfo])] #

Does a lookup by source 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.

This does NOT work for internal dependencies, DO NOT use this
function on those; use `lookupInternalDependency`

instead.

INVARIANT: List of eligible `InstalledPackageInfo`

is non-empty.

lookupInternalDependency :: InstalledPackageIndex -> PackageName -> VersionRange -> LibraryName -> [(Version, [InstalledPackageInfo])] #

Does a lookup by source 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.

INVARIANT: List of eligible `InstalledPackageInfo`

is non-empty.

## Case-insensitive searches

searchByName :: PackageIndex a -> String -> SearchResult [a] #

Does a case-insensitive search by package name.

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

If however several match case-insensitively 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.

data SearchResult a #

None | |

Unambiguous a | |

Ambiguous [a] |

searchByNameSubstring :: PackageIndex a -> String -> [a] #

Does a case-insensitive substring search by package name.

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

## Bulk queries

allPackages :: PackageIndex a -> [a] #

Get all the packages from the index.

allPackagesByName :: PackageIndex a -> [(PackageName, [a])] #

Get all the packages from the index.

They are grouped by package name (case-sensitively).

(Doesn't include private libraries.)

allPackagesBySourcePackageId :: HasUnitId a => PackageIndex a -> [(PackageId, [a])] #

Get all the packages from the index.

They are grouped by source package id (package name and version).

(Doesn't include private libraries)

allPackagesBySourcePackageIdAndLibName :: HasUnitId a => PackageIndex a -> [((PackageId, LibraryName), [a])] #

Get all the packages from the index.

They are grouped by source package id and library name.

This DOES include internal libraries.

## Special queries

brokenPackages :: PackageInstalled a => PackageIndex a -> [(a, [UnitId])] #

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

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

dependencyClosure :: InstalledPackageIndex -> [UnitId] -> Either InstalledPackageIndex [(InstalledPackageInfo, [UnitId])] #

Tries to take the transitive closure of the package dependencies.

If the transitive 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`PackageId`

s do not occur in the index.

reverseDependencyClosure :: PackageInstalled a => PackageIndex a -> [UnitId] -> [a] #

Takes the transitive closure of the packages reverse dependencies.

- The given
`PackageId`

s must be in the index.

topologicalOrder :: PackageInstalled a => PackageIndex a -> [a] #

reverseTopologicalOrder :: PackageInstalled a => PackageIndex a -> [a] #

dependencyInconsistencies :: InstalledPackageIndex -> [(DepUniqueKey, [(UnitId, [InstalledPackageInfo])])] #

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.

dependencyCycles :: PackageInstalled a => PackageIndex a -> [[a]] #

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.

dependencyGraph :: PackageInstalled a => PackageIndex a -> (Graph, Vertex -> a, UnitId -> Maybe Vertex) #

Builds a graph of the package dependencies.

Dependencies on other packages that are not in the index are discarded.
You can check if there are any such dependencies with `brokenPackages`

.

moduleNameIndex :: InstalledPackageIndex -> Map ModuleName [InstalledPackageInfo] #

A rough approximation of GHC's module finder, takes a
`InstalledPackageIndex`

and turns it into a map from module names to their
source packages. It's used to initialize the `build-deps`

field in ```
cabal
init
```

.