Distribution.Configuration

resolveWithFlags :: Monoid a => [(String, [Bool])] -> String -> String -> (String, Version) -> [CondTree ConfVar [d] a] -> ([d] -> DepTestRslt [d]) -> Either [d] ([a], [d], [(String, Bool)])

ignoreConditions :: (Monoid a, Monoid c) => CondTree v c a -> (a, c)

data DepTestRslt d

= DepOk

| MissingDeps d

Documentation

data Flag

A flag can represent a feature to be included, or a way of linking a target against its dependencies, or in fact whatever you can think of.

Constructors

MkFlag

flagName :: String
flagDescription :: String
flagDefault :: Bool

Instances

Show Flag

data ConfVar

A ConfVar represents the variable type used.

Constructors

OS String
Arch String
Flag ConfFlag
Impl String VersionRange

Instances

Eq ConfVar

Show ConfVar

data Condition c

A boolean expression parameterized over the variable type used.

Constructors

Var c
Lit Bool
CNot (Condition c)
COr (Condition c) (Condition c)
CAnd (Condition c) (Condition c)

Instances

Show c => Show (Condition c)

parseCondition :: ReadP r (Condition ConfVar)

Parse a configuration condition from a string.

simplifyCondition

:: Condition c
-> (c -> Either d Bool)	(partial) variable assignment
-> (Condition d, [d])
Simplify the condition and return its free variables.

data CondTree v c a

Constructors

CondNode

condTreeData :: a
condTreeConstraints :: c
condTreeComponents :: [(Condition v, CondTree v c a, Maybe (CondTree v c a))]

Instances

(Show v, Show c) => Show (CondTree v c a)

ppCondTree :: Show v => CondTree v c a -> (c -> Doc) -> Doc

mapTreeData :: (a -> b) -> CondTree v c a -> CondTree v c b

resolveWithFlags

:: Monoid a
=> [(String, [Bool])]	Domain for each flag name, will be tested in order.
-> String	OS name, as returned by System.Info.os
-> String	arch name, as returned by System.Info.arch
-> (String, Version)	Compiler name + version
-> [CondTree ConfVar [d] a]
-> ([d] -> DepTestRslt [d])	Dependency test function.
-> Either [d] ([a], [d], [(String, Bool)])
Try to find a flag assignment that satisfies the constaints of all trees. Returns either the missing dependencies, or a tuple containing the resulting data, the associated dependencies, and the chosen flag assignments. In case of failure, the _smallest_ number of of missing dependencies is returned. [XXX: Could also be specified with a function argument.] XXX: The current algorithm is rather naive. A better approach would be to: Rule out possible paths, by taking a look at the associated dependencies. Infer the required values for the conditions of these paths, and calculate the required domains for the variables used in these conditions. Then picking a flag assignment would be linear (I guess). This would require some sort of SAT solving, though, thus it's not implemented unless we really need it.

ignoreConditions :: (Monoid a, Monoid c) => CondTree v c a -> (a, c)

Flatten a CondTree. This will resolve the CondTree by taking all possible paths into account. Note that since branches represent exclusive choices this may not result in a sane result.

data DepTestRslt d

Result of dependency test. Isomorphic to Maybe d but renamed for clarity.

Constructors

DepOk
MissingDeps d

Instances

Monoid d => Monoid (DepTestRslt d)

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