1 files changed, 22 insertions, 0 deletions
diff --git a/src/Hakyll/Core/Store.hs b/src/Hakyll/Core/Store.hs
index 1208c84..eb2d742 100644
--- a/src/Hakyll/Core/Store.hs
+++ b/src/Hakyll/Core/Store.hs
@@ -9,6 +9,7 @@ module Hakyll.Core.Store
     , new
     , set
     , get
+    , isMember
     , delete
     , hash
     ) where
@@ -101,6 +102,16 @@ cacheLookup (Store _ (Just lru)) key = do
 
 
 --------------------------------------------------------------------------------
+cacheIsMember :: Store -> String -> Bool
+cacheIsMember (Store _ Nothing) _ =  False
+cacheIsMember (Store _ (Just lru)) key =
+    let res = Lru.lookup key lru in
+        case Just res of
+            Nothing -> False
+            _       ->  True
+
+
+--------------------------------------------------------------------------------
 -- | Auxiliary: delete an item from the in-memory cache
 cacheDelete :: Store -> String -> IO ()
 cacheDelete (Store _ Nothing)    _   = return ()
@@ -152,6 +163,17 @@ get store identifier = do
 
 
 --------------------------------------------------------------------------------
+-- | Strict function
+isMember :: Store -> [String] -> IO Bool
+isMember store identifier
+    | cacheIsMember store key = return True
+    | otherwise               = doesFileExist path
+
+    where
+        key = hash identifier
+        path = storeDirectory store </> key
+
+--------------------------------------------------------------------------------
 -- | Delete an item
 delete :: Store -> [String] -> IO ()
 delete store identifier = do