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


-- | Reify a recursive data structure into an explicit graph.
--   
--   'data-reify' provided the ability to turn recursive structures into
--   explicit graphs. Many (implicitly or explicitly) recursive data
--   structure can be given this ability, via a type class instance. This
--   gives an alternative to using <a>Ref</a> for observable sharing.
--   
--   Observable sharing in general is unsafe (hence the module path name
--   Data.Unsafe.Reify), but can be used safely if some simple conditions
--   are met. Typically this package will be used to tie the knot with
--   DSL's that depend of observable sharing, like Lava.
--   
--   Providing an instance for <a>MuRef</a> is the mechanism for allowing a
--   structure to be reified into a graph, and four examples of this are
--   provided.
--   
--   Version 0.2 of data-reify uses <a>StableName</a>s, and is much faster.
--   
--   © 2009 Andy Gill; BSD3 license.
@package data-reify
@version 0.2

module Data.Unsafe.Reify

-- | <a>MuRef</a> is a class that provided a way to reference into a
--   specific type, and a way to map over the deferenced internals.
class MuRef a where { type family DeRef a :: * -> *; }
deRef :: (MuRef a) => a -> (DeRef a) a
mapDeRef :: (MuRef a, Monad m) => (a -> m Unique) -> (DeRef a) a -> m (DeRef a Unique)
data Graph e
Graph :: [(Unique, e Unique)] -> Unique -> Graph e

-- | <a>reifyGraph</a> takes a data structure that admits <a>MuRef</a>, and
--   returns a <a>Graph</a> that contains the dereferenced nodes, with
--   their children as <a>Unique</a> rather than recursive values.
reifyGraph :: (MuRef s) => s -> IO (Graph (DeRef s))
instance (Functor e, Show (e Int)) => Show (Graph e)