The set of parameters to the dependency resolver. These parameters are relatively low level but many kinds of high level policies can be implemented in terms of adjustments to the parameters.

Run the dependency solver.

Since this is potentially an expensive operation, the result is wrapped in a a Progress structure that can be unfolded to provide progress information, logging messages and the final result or an error.

A type to represent the unfolding of an expensive long running calculation that may fail. We may get intermediate steps before the final result which may be used to indicate progress and/or logging messages.

Consume a Progress calculation. Much like foldr for lists but with two base cases, one for a final result and one for failure.

Eg to convert into a simple Either result use:

foldProgress (flip const) Left Right

A simplistic method of resolving a list of target package names to available packages.

Specifically, it does not consider package dependencies at all. Unlike resolveDependencies, no attempt is made to ensure that the selected packages have dependencies that are satisfiable or consistent with each other.

It is suitable for tasks such as selecting packages to download for user inspection. It is not suitable for selecting packages to install.

Note: if no installed package index is available, it is OK to pass mempty. It simply means preferences for installed packages will be ignored.

A package property is a logical predicate on packages.

A package constraint consists of a scope plus a property that must hold for all packages within that scope.

Constructor for a common use case: the constraint applies to the package with the specified name when that package is a top-level dependency in the default namespace.

Global policy for all packages to say if we prefer package versions that are already installed locally or if we just prefer the latest available.

A package selection preference for a particular package.

Preferences are soft constraints that the dependency resolver should try to respect where possible. It is not specified if preferences on some packages are more important than others.

A basic solver policy on which all others are built.

The policy used by all the standard commands, install, fetch, freeze etc (but not the v2-build and related commands).

It extends the basicInstallPolicy with a policy on setup deps.

A fully or partially resolved reference to a package.

Dual of removeUpperBounds

Remove upper bounds in dependencies using the policy specified by the AllowNewer argument (allsomenone).

Note: It's important to apply removeUpperBounds after addSourcePackages. Otherwise, the packages inserted by addSourcePackages won't have upper bounds in dependencies relaxed.

Supply defaults for packages without explicit Setup dependencies

Note: It's important to apply addDefaultSetupDepends after addSourcePackages. Otherwise, the packages inserted by addSourcePackages won't have upper bounds in dependencies relaxed.

If a package has a custom setup then we need to add a setup-depends on Cabal.

Variant of addSetupCabalMinVersionConstraint which sets an upper bound on setup.Cabal labeled with ConstraintSetupCabalMaxVersion.