Props.Internal.PropT

Documentation

type Prop a = PropT Identity a

Pure version of PropT

data PropT m a

A monad transformer for setting up constraint problems.

Instances

MonadTrans PropT

Defined in Props.Internal.PropT

Methods

lift :: Monad m => m a -> PropT m a

Monad m => Monad (PropT m)

Defined in Props.Internal.PropT

Methods

(>>=) :: PropT m a -> (a -> PropT m b) -> PropT m b

(>>) :: PropT m a -> PropT m b -> PropT m b

return :: a -> PropT m a

fail :: String -> PropT m a

Functor m => Functor (PropT m)

Defined in Props.Internal.PropT

Methods

fmap :: (a -> b) -> PropT m a -> PropT m b

(<$) :: a -> PropT m b -> PropT m a

Monad m => Applicative (PropT m)

Defined in Props.Internal.PropT

Methods

pure :: a -> PropT m a

(<*>) :: PropT m (a -> b) -> PropT m a -> PropT m b

liftA2 :: (a -> b -> c) -> PropT m a -> PropT m b -> PropT m c

(*>) :: PropT m a -> PropT m b -> PropT m b

(<*) :: PropT m a -> PropT m b -> PropT m a

MonadIO m => MonadIO (PropT m)

Defined in Props.Internal.PropT

Methods

liftIO :: IO a -> PropT m a

newPVar :: (Monad m, MonoFoldable f, Typeable f, Typeable (Element f)) => f -> PropT m (PVar f)

Used to create a new propagator variable within the setup for your problem.

f is any MonoFoldable container which contains each of the possible states which the variable could take. In practice this most standard containers make a good candidate, it's easy to define a your own instance if needed.

E.g. For a sudoku solver you would use newPVar to create a variable for each cell, passing a Set Int or IntSet containing the numbers [1..9].

constrain :: (Monad m, Typeable g, Typeable (Element f)) => PVar f -> PVar g -> (Element f -> g -> g) -> PropT m ()

constrain the relationship between two PVars. Note that this is a ONE WAY relationship; e.g. constrain a b f will propagate constraints from a to b but not vice versa.

Given PVar f and PVar g as arguments, provide a function which will filter/alter the options in g according to the choice.

For a sudoku puzzle f and g each represent cells on the board. If f ~ Set Int and g ~ Set Int, then you might pass a constraint filter:

constrain a b $ \elementA setB -> S.delete elementA setB)

Take a look at some linking functions which are already provided: disjoint, equal, require

solve :: (Functor f, Typeable (Element g)) => Prop (f (PVar g)) -> Maybe (f (Element g))

Pure version of solveT

solveAll :: (Functor f, Typeable (Element g)) => Prop (f (PVar g)) -> [f (Element g)]

Pure version of solveAllT

readPVar :: Typeable (Element f) => Graph -> PVar f -> Element f

data PVar f

A propagator variable where the possible values are contained in the MonoFoldable type f.

Instances

Eq (PVar f)

Nominal equality, Ignores contents

Defined in Props.Internal.PropT

Methods

(==) :: PVar f -> PVar f -> Bool

(/=) :: PVar f -> PVar f -> Bool

Ord (PVar f)

Nominal ordering, Ignores contents.

Defined in Props.Internal.PropT

Methods

compare :: PVar f -> PVar f -> Ordering

(<) :: PVar f -> PVar f -> Bool

(<=) :: PVar f -> PVar f -> Bool

(>) :: PVar f -> PVar f -> Bool

(>=) :: PVar f -> PVar f -> Bool

max :: PVar f -> PVar f -> PVar f

min :: PVar f -> PVar f -> PVar f

Show (PVar f)

Defined in Props.Internal.PropT

Methods

showsPrec :: Int -> PVar f -> ShowS

show :: PVar f -> String

showList :: [PVar f] -> ShowS