[commit: ghc] master: Minor refactoring (461c831)

[git at git.haskell.org]

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

On branch  : master
Link       : http://ghc.haskell.org/trac/ghc/changeset/461c83162d70eaf1ab6cb2c45bc590ddee2a9147/ghc

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

commit 461c83162d70eaf1ab6cb2c45bc590ddee2a9147
Author: Simon Peyton Jones <simonpj at microsoft.com>
Date:   Thu Oct 5 15:02:45 2017 +0100

    Minor refactoring
    
    I'm trying to understand Check.hs.  This patch is a very
    minor refactoring.  No change in behaviour.


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

461c83162d70eaf1ab6cb2c45bc590ddee2a9147
 compiler/deSugar/Check.hs | 32 ++++++++++++++++----------------
 1 file changed, 16 insertions(+), 16 deletions(-)

diff --git a/compiler/deSugar/Check.hs b/compiler/deSugar/Check.hs
index 23e4f0e..8fb9553 100644
--- a/compiler/deSugar/Check.hs
+++ b/compiler/deSugar/Check.hs
@@ -109,20 +109,20 @@ liftD m = ListT $ \sk fk -> m >>= \a -> sk a fk
 -- users' guide. If you update the implementation of this function, make sure
 -- to update that section of the users' guide as well.
 getResult :: PmM PmResult -> DsM PmResult
-getResult ls = do
-  res <- fold ls goM (pure Nothing)
-  case res of
-    Nothing -> panic "getResult is empty"
-    Just a -> return a
+getResult ls
+  = do { res <- fold ls goM (pure Nothing)
+       ; case res of
+            Nothing -> panic "getResult is empty"
+            Just a  -> return a }
   where
     goM :: PmResult -> DsM (Maybe PmResult) -> DsM (Maybe PmResult)
-    goM mpm dpm = do
-      pmr <- dpm
-      return $ go pmr mpm
+    goM mpm dpm = do { pmr <- dpm
+                     ; return $ Just $ go pmr mpm }
+
     -- Careful not to force unecessary results
-    go :: Maybe PmResult -> PmResult -> Maybe PmResult
-    go Nothing rs = Just rs
-    go old@(Just (PmResult prov rs (UncoveredPatterns us) is)) new
+    go :: Maybe PmResult -> PmResult -> PmResult
+    go Nothing rs = rs
+    go (Just old@(PmResult prov rs (UncoveredPatterns us) is)) new
       | null us && null rs && null is = old
       | otherwise =
         let PmResult prov' rs' (UncoveredPatterns us') is' = new
@@ -130,8 +130,8 @@ getResult ls = do
                 `mappend` (compareLength is is')
                 `mappend` (compareLength rs rs')
                 `mappend` (compare prov prov') of
-              GT  -> Just new
-              EQ  -> Just new
+              GT  -> new
+              EQ  -> new
               LT  -> old
     go (Just (PmResult _ _ (TypeOfUncovered _) _)) _new
       = panic "getResult: No inhabitation candidates"
@@ -281,9 +281,9 @@ instance Monoid PartialResult where
 --
 data PmResult =
   PmResult {
-      pmresultProvenance :: Provenance
-    , pmresultRedundant :: [Located [LPat GhcTc]]
-    , pmresultUncovered :: UncoveredCandidates
+      pmresultProvenance   :: Provenance
+    , pmresultRedundant    :: [Located [LPat GhcTc]]
+    , pmresultUncovered    :: UncoveredCandidates
     , pmresultInaccessible :: [Located [LPat GhcTc]] }
 
 -- | Either a list of patterns that are not covered, or their type, in case we