-----------------------------------------------------------------------------
-- |
-- Module      :  Generics.MultiRec.Rewriting
-- Copyright   :  (c) 2008 Universiteit Utrecht
-- License     :  BSD3
--
-- Maintainer  :  generics@haskell.org
-- Stability   :  experimental
-- Portability :  non-portable
--
-- By importing this module, the user is able to use all the rewriting
-- machinery. The user is only required to provide an instance of 
-- @Ix@ for each datatype and @Rewrite@ for each system of datatypes.
--
-- Consider a system of datatypes representing the abstract syntax tree 
-- of a simple language:
--
-- @
--  data Expr   =  Const  Int
--              |  Add    Expr  Expr
--              |  Mul    Expr  Expr
--              |  EVar   Var
--              |  Let    Decl  Expr
--    deriving Show
--
--  data Decl   =  Var := Expr
--              |  Seq    Decl  Decl
--              |  None
--    deriving Show
--
--  type Var   =  String
-- @
--
-- The instances of @Ix@ could be manually written (see examples/ASTUse.hs).
-- Fortunately, there is some Template Haskell code to help generate them.
-- The easiest way is then to write:
--
-- @
--  data AST :: * -> * where
--    Expr  ::  AST Expr
--    Decl  ::  AST Decl
--    Var   ::  AST Var
--
--  $(deriveConstructors [''Expr, ''Decl, ''Var])
--
--  $(deriveSystem ''AST [''Expr, ''Decl, ''Var] "PFAST")
--  type instance PF AST = PFAST
-- @
--
-- Additionally, the instance @Rewrite@ would look like:
--
-- @
--   instance Rewrite AST
-- @
--
-- Build rules like this:
--
-- @
--   inlineRule :: Var -> Expr -> RuleSpec Expr
--   inlineRule var expr = Let (var := expr) (EVar var) :~> expr
-- @
--
-- And apply them as follows:
--
-- @
--   test :: Expr
--   test = rewrite (rule Expr inlineRule)
--                  (Let ("x" := Mul (Const 6) (Const 9)) (EVar "x"))
-- @
--

-----------------------------------------------------------------------------

module Generics.MultiRec.Rewriting (
    module Generics.MultiRec.Rewriting.Rewriting
  , module Generics.MultiRec.Rewriting.Rules
  , module Generics.MultiRec.Rewriting.Strategies
  )
  
  where

import Generics.MultiRec.Rewriting.Rewriting
import Generics.MultiRec.Rewriting.Rules
import Generics.MultiRec.Rewriting.Strategies