-- Hoogle documentation, generated by Haddock
-- See Hoogle, http://www.haskell.org/hoogle/


-- | Dependency resolution for package management
--   
--   A library for resolving dependencies; uses a topological sort to
--   construct a build plan and then allows choice between all compatible
--   plans.
@package dependency
@version 0.1.0.10

module Data.Dependency

-- | Heuristics:
--   
--   <ol>
--   <li>Always use a newer version when possible</li>
--   <li>Obey constraints</li>
--   <li>Specify an error for circular dependencies</li>
--   <li>Specify an error for overconstrained builds</li>
--   <li>Specify an error if a package is not present</li>
--   </ol>
--   
--   This doesn't do any package resolution beyond versioning.
resolveDependencies :: PackageSet Dependency -> [Dependency] -> DepM [[Dependency]]
buildSequence :: [Dependency] -> [[Dependency]]

-- | Check a given dependency is compatible with in-scope dependencies.
check :: Dependency -> [Dependency] -> Bool

-- | A generic dependency, consisting of a package name and version, as
--   well as dependency names and their constraints.
data Dependency
Dependency :: String -> [(String, Constraint Version)] -> Version -> Dependency
[_libName] :: Dependency -> String
[_libDependencies] :: Dependency -> [(String, Constraint Version)]
[_libVersion] :: Dependency -> Version

-- | A package set is simply a map between package names and a set of
--   packages.
newtype PackageSet a
PackageSet :: Map String (Set a) -> PackageSet a
[_packageSet] :: PackageSet a -> Map String (Set a)
newtype Version
Version :: [Integer] -> Version
type DepM = Either ResolveError

-- | An error that can occur during package resolution.
data ResolveError
InternalError :: ResolveError
NotPresent :: String -> ResolveError
Conflicts :: [String] -> String -> ResolveError

-- | Monoid/functor for representing constraints.
data Constraint a
LessThanEq :: a -> Constraint a
GreaterThanEq :: a -> Constraint a
Eq :: a -> Constraint a
Bounded :: (Constraint a) -> (Constraint a) -> Constraint a
None :: Constraint a

-- | We use a tardis monad here to give ourselves greater flexibility
--   during dependency solving.
newtype ResolveStateM m a
ResolveStateM :: TardisT Mod ResMap m a -> ResolveStateM m a
[unResolve] :: ResolveStateM m a -> TardisT Mod ResMap m a
type ResolveState = ResolveStateM (Either ResolveError)
type ResMap = Map String Dependency