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authorGravatar Joey Hess <joey@kitenet.net>2011-05-15 02:49:43 -0400
committerGravatar Joey Hess <joey@kitenet.net>2011-05-15 03:38:08 -0400
commitcad0e1c8b7eb21f8dceca8dd9fa3bc1d1aa7eabd (patch)
treeb6be12dc1cc83a35ca7d89a862d85e6d71c38572 /Backend.hs
parentefa7f544050c0d5be6bc1b0fc0125278e475c213 (diff)
simplified a bunch of Maybe handling
Diffstat (limited to 'Backend.hs')
-rw-r--r--Backend.hs29
1 files changed, 10 insertions, 19 deletions
diff --git a/Backend.hs b/Backend.hs
index aec87ce66..6140664ce 100644
--- a/Backend.hs
+++ b/Backend.hs
@@ -76,10 +76,9 @@ list = do
{- Looks up a backend in a list. May fail if unknown. -}
lookupBackendName :: [Backend Annex] -> String -> Backend Annex
-lookupBackendName bs s =
- case maybeLookupBackendName bs s of
- Just b -> b
- Nothing -> error $ "unknown backend " ++ s
+lookupBackendName bs s = maybe unknown id $ maybeLookupBackendName bs s
+ where
+ unknown = error $ "unknown backend " ++ s
maybeLookupBackendName :: [Backend Annex] -> String -> Maybe (Backend Annex)
maybeLookupBackendName bs s =
if 1 /= length matches
@@ -91,23 +90,18 @@ maybeLookupBackendName bs s =
storeFileKey :: FilePath -> Maybe (Backend Annex) -> Annex (Maybe (Key, Backend Annex))
storeFileKey file trybackend = do
bs <- list
- let bs' = case trybackend of
- Nothing -> bs
- Just backend -> backend:bs
+ let bs' = maybe bs (:bs) trybackend
storeFileKey' bs' file
storeFileKey' :: [Backend Annex] -> FilePath -> Annex (Maybe (Key, Backend Annex))
storeFileKey' [] _ = return Nothing
-storeFileKey' (b:bs) file = do
- result <- (B.getKey b) file
- case result of
- Nothing -> nextbackend
- Just key -> do
+storeFileKey' (b:bs) file = maybe nextbackend store =<< (B.getKey b) file
+ where
+ nextbackend = storeFileKey' bs file
+ store key = do
stored <- (B.storeFileKey b) file key
if (not stored)
then nextbackend
else return $ Just (key, b)
- where
- nextbackend = storeFileKey' bs file
{- Attempts to retrieve an key from one of the backends, saving it to
- a specified location. -}
@@ -148,11 +142,8 @@ lookupFile file = do
getsymlink = do
l <- readSymbolicLink file
return $ takeFileName l
- makekey bs l =
- case fileKey l of
- Just k -> makeret k l bs
- Nothing -> return Nothing
- makeret k l bs =
+ makekey bs l = maybe (return Nothing) (makeret bs l) (fileKey l)
+ makeret bs l k =
case maybeLookupBackendName bs bname of
Just backend -> return $ Just (k, backend)
Nothing -> do