for(M->)_; add traverse_, for_ into Utils

Author: Anton-Latukha

main/Main.hs

@@ -17,7 +17,6 @@ import           Control.Monad
 import           Control.Monad.Catch
 import           Control.Monad.Free
 import           Control.Monad.IO.Class
-import           Data.Foldable                  ( traverse_ )
 import qualified Data.HashMap.Lazy             as M
 import qualified Data.Map                      as Map
 import           Data.List                      ( sortOn )
@@ -180,7 +179,7 @@ main = do
               )
               (\ v -> pure (k, pure (Free v)))
               nv
-          forM_ xs $ \(k, mv) -> do
+          for_ xs $ \(k, mv) -> do
             let path              = prefix <> Text.unpack k
                 (report, descend) = filterEntry path k
             when report $ do

main/Repl.hs

@@ -102,7 +102,7 @@ main' iniVal = initState iniVal >>= \s -> flip evalStateT s
 
   rcFile = do
     f <- liftIO $ Data.Text.IO.readFile ".hnixrc" `catch` handleMissing
-    forM_ (fmap (words . Data.Text.unpack) $ Data.Text.lines f) $ \case
+    for_ (words . Data.Text.unpack <$> Data.Text.lines f) $ \case
       ((prefix:command) : xs) | prefix == commandPrefix -> do
         let arguments = unwords xs
         optMatcher command options arguments
@@ -269,7 +269,7 @@ browse :: (MonadNix e t f m, MonadIO m)
        -> Repl e t f m ()
 browse _ = do
   st <- get
-  forM_ (Data.HashMap.Lazy.toList $ replCtx st) $ \(k, v) -> do
+  for_ (Data.HashMap.Lazy.toList $ replCtx st) $ \(k, v) -> do
     liftIO $ putStr $ Data.Text.unpack $ k <> " = "
     printValue v
 
@@ -298,7 +298,7 @@ typeof args = do
     Nothing  -> do
       exec False line
 
-  forM_ mVal $ \val -> do
+  for_ mVal $ \val -> do
     s <- lift . lift . showValueType $ val
     liftIO $ putStrLn s
 
@@ -525,7 +525,7 @@ help :: (MonadNix e t f m, MonadIO m)
      -> Repl e t f m ()
 help hs _ = do
   liftIO $ putStrLn "Available commands:\n"
-  forM_ hs $ \h ->
+  for_ hs $ \h ->
     liftIO .
       Data.Text.IO.putStrLn .
         Prettyprinter.Render.Text.renderStrict .

src/Nix/Type/Assumption.hs

@@ -15,7 +15,7 @@ import           Prelude                 hiding ( lookup )
 
 import           Nix.Type.Type
 
-import           Data.Foldable
+import           Data.Foldable                  ( foldl' )
 
 newtype Assumption = Assumption { assumptions :: [(Name, Type)] }
   deriving (Eq, Show)

src/Nix/Type/Env.hs

@@ -18,7 +18,7 @@ import           Prelude                 hiding ( lookup )
 
 import           Nix.Type.Type
 
-import           Data.Foldable           hiding ( toList )
+import           Data.Foldable                  ( foldl' )
 import qualified Data.Map                      as Map
 
 ---------------------------------------------------------------------------------

src/Nix/Type/Infer.hs

@@ -41,7 +41,10 @@ import           Control.Monad.Ref
 import           Control.Monad.ST
 import           Control.Monad.State.Strict
 import           Data.Fix                       ( foldFix )
-import           Data.Foldable
+import           Data.Foldable                  ( foldl'
+                                                , foldrM
+                                                , find
+                                                )
 import qualified Data.HashMap.Lazy             as M
 import           Data.List                      ( delete
                                                 , nub

src/Nix/Utils.hs

@@ -265,3 +265,15 @@ ifPure f =
   free
     f
     mempty
+
+-- From @base@ @Data.Foldable@
+traverse_ :: (Foldable t, Applicative f) => (a -> f b) -> t a -> f ()
+traverse_ f = foldr c (pure ())
+  -- See Note [List fusion and continuations in 'c']
+  where c x k = f x *> k
+        {-# inline c #-}
+
+-- From @base@ @Data.Foldable@
+for_ :: (Foldable t, Applicative f) => t a -> (a -> f b) -> f ()
+for_ = flip traverse_
+{-# inline for_ #-}

src/Nix/Value/Equal.hs

@@ -56,7 +56,7 @@ alignEqM eq fa fb = fmap (either (const False) (const True)) $ runExceptT $ do
   pairs <- forM (Data.Align.align fa fb) $ \case
     These a b -> pure (a, b)
     _         -> throwE ()
-  forM_ pairs $ \(a, b) -> guard =<< lift (eq a b)
+  for_ pairs $ \(a, b) -> guard =<< lift (eq a b)
 
 alignEq :: (Align f, Traversable f) => (a -> b -> Bool) -> f a -> f b -> Bool
 alignEq eq fa fb = runIdentity $ alignEqM (\x y -> Identity (eq x y)) fa fb

tests/Main.hs

@@ -23,6 +23,7 @@ import           Nix.Options
 import           Nix.Parser
 import           Nix.Standard
 import           Nix.Value
+import           Nix.Utils
 import qualified NixLanguageTests
 import qualified ParserTests
 import qualified PrettyTests
@@ -68,7 +69,7 @@ ensureNixpkgsCanParse =
         when (null files) $
           errorWithoutStackTrace $
             "Directory " <> show dir <> " does not have any files"
-        forM_ files $ \file -> do
+        for_ files $ \file -> do
           unless ("azure-cli/default.nix" `isSuffixOf` file ||
                   "os-specific/linux/udisks/2-default.nix"  `isSuffixOf` file) $ do
             -- Parse and deepseq the resulting expression tree, to ensure the

tests/ParserTests.hs

@@ -22,7 +22,7 @@ import Prettyprinter.Render.Text
 import Test.Tasty
 import Test.Tasty.HUnit
 import Test.Tasty.TH
-import Data.Foldable (traverse_)
+import Nix.Utils
 
 case_constant_int = assertParseText "234" $ mkInt 234