Commit 1690bf71 authored by bbr's avatar bbr
Browse files

added library global

- external functions implemented
- but to work more help from compiler is needed: constants of type global must not get state argument
parent 0e2aef0b
......@@ -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)
......
------------------------------------------------------------------------------
--- 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
------------------------------------------------------------------------
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