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


-- | Non-Determinism Monad for Level-Wise Search
--   
--   This Haskell library provides an implementation of the MonadPlus type
--   class that enumerates the levels of the search space and allows to
--   implement breadth-first search.
@package level-monad
@version 0.2


-- | This library provides an implementation of the MonadPlus type class
--   that enumerates the levels of the search space and allows to implement
--   breadth-first search.
--   
--   The implementation is inspired by Mike Spivey and Silvija Seres: cf.
--   Chapter 9 of the book 'The Fun of Programming'.
--   
--   Warning: <tt>Levels</tt> is only a monad when the results of the
--   enumeration functions are interpreted as a multiset, i.e., a valid
--   transformation according to the monad laws may change the order of the
--   results.
module Control.Monad.Levels

-- | Non-Deterministic computations of type <tt>Levels a</tt> can be
--   searched level-wise.
data Levels a

-- | The function <tt>levels</tt> yields the results of a non-deterministic
--   computation grouped in levels.
levels :: Levels a -> [[a]]

-- | The function <tt>breadthFirstSearch</tt> enumerates the results of a
--   non-deterministic computation in breadth-first order.
breadthFirstSearch :: Levels a -> [a]

-- | The function <tt>levelDiagonalisation</tt> enumerates the results of a
--   non-deterministic computation by diagonally interleaving the results
--   of all levels.
levelDiagonalisation :: Levels a -> [a]
instance MonadPlus Levels
instance Monad Levels