[commit: ghc] wip/nfs-locking: Simplify using firstJustM (8933a3a)

[git at git.haskell.org]

Repository : ssh://git@git.haskell.org/ghc

On branch  : wip/nfs-locking
Link       : http://ghc.haskell.org/trac/ghc/changeset/8933a3a8235a642638ef8e7e5e7c91777829535b/ghc

>---------------------------------------------------------------

commit 8933a3a8235a642638ef8e7e5e7c91777829535b
Author: Andrey Mokhov <andrey.mokhov at gmail.com>
Date:   Sun May 22 02:10:55 2016 +0100

    Simplify using firstJustM


>---------------------------------------------------------------

8933a3a8235a642638ef8e7e5e7c91777829535b
 src/Oracles/Dependencies.hs | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/Oracles/Dependencies.hs b/src/Oracles/Dependencies.hs
index d6cdbd3..a458b6d 100644
--- a/src/Oracles/Dependencies.hs
+++ b/src/Oracles/Dependencies.hs
@@ -24,8 +24,7 @@ fileDependencies :: Context -> FilePath -> Action (FilePath, [FilePath])
 fileDependencies context obj = do
     let path = buildPath context -/- ".dependencies"
     -- If no dependencies found, try to drop the way suffix (for *.c sources).
-    deps <- listToMaybe . catMaybes <$>
-            mapM (askOracle . ObjDepsKey . (,) path) [obj, obj -<.> "o"]
+    deps <- firstJustM (askOracle . ObjDepsKey . (,) path) [obj, obj -<.> "o"]
     case deps of
         Nothing -> error $ "No dependencies found for file " ++ obj
         Just [] -> error $ "No source file found for file " ++ obj