Control.Monad.Atom

The Atom monad provides functions which convert objects to unique atoms (represented as Ints). Example:

 example = evalAtom $ do
   xs <- mapM toAtom "abcabd"
   zs <- mapM fromAtom xs
   return $ zip zs xs

>>> example
>>> [('a',0),('b',1),('c',2),('a',0),('b',1),('d',3)]

Documentation

data AtomTable a

AtomTable holds the state necessary for converting to and from Ints.

Instances

Generic (AtomTable a)

data Atom a r

Atom is a specialized state monad for converting to and from Ints.

Instances

Monad (Atom a)

Functor (Atom a)

Ord a => MonadAtom (Atom a)

toAtom :: MonadAtom m => Key m -> m Int

toAtom x converts x to a unique Int in the Atom monad

fromAtom :: MonadAtom m => Int -> m (Key m)

fromAtom i converts the Int i to its corresponding object in the Atom monad.

maybeToAtom :: MonadAtom m => Key m -> m (Maybe Int)

maybeToAtom x converts x to a unique Int in the Atom monad only if x already has a corresponding Int

empty :: Ord a => AtomTable a

empty is the initial empty AtomTable

evalAtom :: Ord a => Atom a r -> r

evalAtom c runs computation c in the Atom monad with the empty initial AtomTable.

runAtom :: Ord a => Atom a r -> AtomTable a -> (r, AtomTable a)

runAtom c s runs computation c in the Atom monad with the initial AtomTable s.

mapping :: Ord a => AtomTable a -> Map a Int

The mapping stored in the atom table