Control.Monad.Weighted.Class

Documentation

class (Semiring w, Monad m) => MonadWeighted w m | m -> w where

A class for computations which carry a weight with them. It is analogous to Writer over the Product Monoid.

Methods

weighted :: (a, w) -> m a

weighted (a,w) embeds a simple weighted action.

weight :: w -> m ()

weight w is an action that produces the output w.

weigh :: m a -> m (a, w)

weigh m is an action that executes the action m and adds its output to the value of the computation.

scale :: m (a, w -> w) -> m a

scale m is an action that executes the action m, which returns a value and a function, and returns the value, applying the function to the output.

Instances

MonadWeighted w m => MonadWeighted w (MaybeT m)

Methods

weighted :: (a, w) -> MaybeT m a

weight :: w -> MaybeT m ()

weigh :: MaybeT m a -> MaybeT m (a, w)

scale :: MaybeT m (a, w -> w) -> MaybeT m a

MonadWeighted w m => MonadWeighted w (StateT s m)

Methods

weighted :: (a, w) -> StateT s m a

weight :: w -> StateT s m ()

weigh :: StateT s m a -> StateT s m (a, w)

scale :: StateT s m (a, w -> w) -> StateT s m a

MonadWeighted w m => MonadWeighted w (StateT s m)

Methods

weighted :: (a, w) -> StateT s m a

weight :: w -> StateT s m ()

weigh :: StateT s m a -> StateT s m (a, w)

scale :: StateT s m (a, w -> w) -> StateT s m a

MonadWeighted w m => MonadWeighted w (IdentityT * m)

Methods

weighted :: (a, w) -> IdentityT * m a

weight :: w -> IdentityT * m ()

weigh :: IdentityT * m a -> IdentityT * m (a, w)

scale :: IdentityT * m (a, w -> w) -> IdentityT * m a

MonadWeighted w m => MonadWeighted w (ExceptT e m)

Methods

weighted :: (a, w) -> ExceptT e m a

weight :: w -> ExceptT e m ()

weigh :: ExceptT e m a -> ExceptT e m (a, w)

scale :: ExceptT e m (a, w -> w) -> ExceptT e m a

(DetectableZero w, Monad m, Alternative m) => MonadWeighted w (FilterT w m)

Methods

weighted :: (a, w) -> FilterT w m a

weight :: w -> FilterT w m ()

weigh :: FilterT w m a -> FilterT w m (a, w)

scale :: FilterT w m (a, w -> w) -> FilterT w m a

(Semiring w, Monad m) => MonadWeighted w (WeightedT w m)

Methods

weighted :: (a, w) -> WeightedT w m a

weight :: w -> WeightedT w m ()

weigh :: WeightedT w m a -> WeightedT w m (a, w)

scale :: WeightedT w m (a, w -> w) -> WeightedT w m a

MonadWeighted w m => MonadWeighted w (ReaderT * r m)

Methods

weighted :: (a, w) -> ReaderT * r m a

weight :: w -> ReaderT * r m ()

weigh :: ReaderT * r m a -> ReaderT * r m (a, w)

scale :: ReaderT * r m (a, w -> w) -> ReaderT * r m a

collect :: (Foldable m, MonadWeighted w m) => m a -> w

Collect the total weight of a computation.

toCovector :: (Foldable m, MonadWeighted w m) => m a -> (a -> w) -> w

Transform a weighted computation to a covector.