added library global

- external functions implemented
- but to work more help from compiler is needed: constants of type global must not get state argument

src/lib/ExternalFunctionsIOExts.hs

@@ -48,7 +48,7 @@ prim_getAssoc key _ = C_IO (\_ -> do
          as <- getAssocs
          return (IOVal (maybe C_Nothing C_Just (lookup key as))))
 
-
+ 
 
 newIORef :: Curry t0 => t0 -> Result (C_IO (C_IORef t0))
 newIORef x = ioFunc0 (Ref.newIORef x) 

src/lib/Global.curry

+------------------------------------------------------------------------------
+--- Library for handling global entities.
+--- A global entity has a name declared in the program.
+--- Its value can be accessed and modified by IO actions.
+--- Furthermore, global entities can be declared as persistent so that
+--- their values are stored across different program executions.
+---
+--- Currently, it is still experimental so that its interface might
+--- be slightly changed in the future.
+---
+--- A global entity <code>g</code> with an initial value <code>v</code>
+--- of type <code>t</code> must be declared by:
+--- 
+--- <code>g :: Global t</code><br/>
+--- <code>g = global v spec</code>
+---
+--- Here, the type <code>t</code> must not contain type variables and
+--- <code>spec</code> specifies the storage mechanism for the
+--- global entity (see type <code>GlobalSpec</code>).
+---
+---
+--- @author Michael Hanus
+--- @version June 2007
+------------------------------------------------------------------------------
+
+module Global(Global,GlobalSpec(..),global,readGlobal,writeGlobal) where
+
+----------------------------------------------------------------------
+
+--- The general type of dynamic predicates.
+data Global a -- = GlobalDef a GlobalSpec
+
+--- <code>global</code> is only used for the declaration of a global value
+--- and should not be used elsewhere. In the future, it might become a keyword.
+global :: a -> GlobalSpec -> Global a
+global external --v s = GlobalDef v s
+
+--- The storage mechanism for the global entity.
+--- @cons Temporary - the global value exists only during a single execution
+---                   of a program
+--- @cons Persistent f - the global value is stored persisently in file f
+---                     (which is created and initialized if it does not exists)
+data GlobalSpec = Temporary  | Persistent String
+
+
+--- Reads the current value of a global.
+readGlobal :: Global a -> IO a
+readGlobal g = prim_readGlobal $# g
+
+prim_readGlobal :: Global a -> IO a
+prim_readGlobal external
+
+
+--- Updates the value of a global.
+--- The value is evaluated to a ground constructor term before it is updated.
+writeGlobal :: Global a -> a -> IO ()
+writeGlobal g v = (prim_writeGlobal $# g) $## v
+
+prim_writeGlobal :: Global a -> a -> IO ()
+prim_writeGlobal external
+
+
+------------------------------------------------------------------------