GHC.Base.breakpoint isn't vaporware anymore.

[ghc-hetmet.git] / ghc / compiler / ghci / Linker.lhs

diff --git a/ghc/compiler/ghci/Linker.lhs b/ghc/compiler/ghci/Linker.lhs
index 44efac8..3a5ecf8 100644 (file)
--- a/ghc/compiler/ghci/Linker.lhs
+++ b/ghc/compiler/ghci/Linker.lhs
@@ -16,9 +16,9 @@ necessary.
 {-# OPTIONS -optc-DNON_POSIX_SOURCE -#include "Linker.h" #-}
 
 module Linker ( HValue, showLinkerState,
-               linkExpr, unload, extendLinkEnv,
+               linkExpr, unload, extendLinkEnv, withExtendedLinkEnv,
                 extendLoadedPkgs,
-               linkPackages,
+               linkPackages,initDynLinker
        ) where
 
 #include "HsVersions.h"
@@ -54,7 +54,7 @@ import Data.List      ( partition, nub )
 import System.IO       ( putStr, putStrLn, hPutStrLn, stderr, fixIO )
 import System.Directory        ( doesFileExist )
 
-import Control.Exception ( block, throwDyn )
+import Control.Exception ( block, throwDyn, bracket )
 import Maybe           ( isJust, fromJust )
 
 #if __GLASGOW_HASKELL__ >= 503
@@ -137,6 +137,18 @@ extendLinkEnv new_bindings
            new_pls = pls { closure_env = new_closure_env }
        writeIORef v_PersistentLinkerState new_pls
 
+withExtendedLinkEnv :: [(Name,HValue)] -> IO a -> IO a
+withExtendedLinkEnv new_env action
+    = bracket set_new_env
+              reset_old_env
+              (const action)
+    where set_new_env = do pls <- readIORef v_PersistentLinkerState
+                           let new_closure_env = extendClosureEnv (closure_env pls) new_env
+                               new_pls = pls { closure_env = new_closure_env }
+                           writeIORef v_PersistentLinkerState new_pls
+                           return pls
+          reset_old_env pls = writeIORef v_PersistentLinkerState pls
+
 -- filterNameMap removes from the environment all entries except 
 --     those for a given set of modules;
 -- Note that this removes all *local* (i.e. non-isExternal) names too