Merge #945: Refactors

I've switched to "pre 0.9" type of ChangeLog. *(no logging)*

Huge release `0.13` - tested the waters & showed from reality that we do not need to maintain that kind of open API and so that volume of ChangeLog, as those who use HNix as a library (mainly DHall) - use `Shorthands` module & that is pretty much all, and all others were notified & not showed-up to show any concerns.

People were notified in ChangeLog & the channel & I frequently talk about that we need to close the API to be able to not keep & dump that volume of changelog & "major API (no one uses) functionality breakage releases" on ourselves (me) & users, and there is no other way to make reorganization to form multiple packages, multiple packages - is a major breakage anyway, we would need to untie uncycle all dependencies between created packages & that in itself can be a big effort.

So, in short - do not see need from users, the point or the possibility to keep a changelog during that volume of breakage & reorganization.

As always, if someone would need help - happy to help to migrate.

This is needed to save everyone's efforts upfront: ["Internal" modules is a mistake](http://nikita-volkov.github.io/internal-convention-is-a-mistake/)

That is why I stand for #823, package splitting would save a lot of effort for maintainers & for users.

Author: Anton-Latukha

ChangeLog.md

@@ -3,11 +3,20 @@
 
 ## [(diff)](https://github.com/haskell-nix/hnix/compare/0.13.1...master#files_bucket) WIP
 
-Breaking:
+* Breaking:
 
   * `Nix.Effects`:
     * rm `pathExits` in favour of `doesPathExist` (in `Nix.Render`: `class MonadFile`: `doesPathExist`)
 
+  * `Nix.Var`: was found being superflous ([report](https://github.com/haskell-nix/hnix/issues/946)), so reduced. use `Control.Monad.Ref` instead.
+
+  * `Nix.Normal`
+    * rename `opaque(,->Val)`, indicate that it is a literal.
+  
+  * `Nix.Thunk`:
+    * `class MonadThunkId m => MonadThunk{,F} t m a`:
+      * rename `query(M->){,F}`
+
 * Additional:
 
   * `Nix.Utils`:
@@ -25,6 +34,7 @@ Breaking:
   * `Nix.Type.Env`:
     * added instances:
       * `Env`: `{Semigroup,Monoid,One}`
+  
   * `Nix`:
     * changed argument order:
       * `nixEval`:
@@ -38,8 +48,9 @@ Breaking:
 
   * `Nix.Normal`
     * add `thunkVal` literal & use it where appropriate `{deThunk, removeEffects}`
-    * rename `opaque(,->Val)`, indicate that it is a literal.
-       
+      
+  * `Nix.Thunk.Basic`:
+    * export `deferred`
 
 
 ### [(diff)](https://github.com/haskell-nix/hnix/compare/0.13.0.1...0.13.1#files_bucket) 0.13.1 (2021-05-22)

hnix.cabal

@@ -400,7 +400,9 @@ library
       base hiding (Prelude)
     , relude (Relude as Prelude)
     , relude
-  ghc-options: -Wall -fprint-potential-instances
+  ghc-options:
+    -Wall
+    -fprint-potential-instances
   build-depends:
       aeson >= 1.4.2 && < 1.6
     , array >= 0.4 && < 0.6
@@ -485,7 +487,10 @@ library
   if flag(optimize)
     default-extensions:
       ApplicativeDo
-    ghc-options: -fexpose-all-unfoldings -fspecialise-aggressively -O2
+    ghc-options:
+      -O2
+      -fexpose-all-unfoldings
+      -fspecialise-aggressively
   -- if !flag(profiling)
   --   build-depends:
   --       ghc-datasize
@@ -500,7 +505,8 @@ executable hnix
     Paths_hnix
   autogen-modules:
     Paths_hnix
-  ghc-options: -Wall
+  ghc-options:
+    -Wall
   build-depends:
       aeson
     , base
@@ -547,7 +553,10 @@ executable hnix
   if flag(optimize)
     default-extensions:
       ApplicativeDo
-    ghc-options: -fexpose-all-unfoldings -fspecialise-aggressively -O2
+    ghc-options:
+      -O2
+      -fexpose-all-unfoldings
+      -fspecialise-aggressively
   if impl(ghc < 8.10)
     -- GHC < 8.10 comes with haskeline < 0.8, which we don't support.
     -- To simplify CI, we just disable the component.
@@ -571,7 +580,9 @@ test-suite hnix-tests
     , relude
   hs-source-dirs:
     tests
-  ghc-options: -Wall -threaded
+  ghc-options:
+    -Wall
+    -threaded
   build-depends:
       Diff
     , Glob
@@ -620,7 +631,10 @@ test-suite hnix-tests
   if flag(optimize)
     default-extensions:
       ApplicativeDo
-    ghc-options: -fexpose-all-unfoldings -fspecialise-aggressively -O2
+    ghc-options:
+      -O2
+      -fexpose-all-unfoldings
+      -fspecialise-aggressively
   default-language: Haskell2010
 
 benchmark hnix-benchmarks
@@ -634,7 +648,8 @@ benchmark hnix-benchmarks
       base hiding (Prelude)
     , relude (Relude as Prelude)
     , relude
-  ghc-options: -Wall
+  ghc-options:
+    -Wall
   build-depends:
       base
     , criterion
@@ -668,5 +683,8 @@ benchmark hnix-benchmarks
   if flag(optimize)
     default-extensions:
       ApplicativeDo
-    ghc-options: -fexpose-all-unfoldings -fspecialise-aggressively -O2
+    ghc-options:
+      -O2
+      -fexpose-all-unfoldings
+      -fspecialise-aggressively
   default-language: Haskell2010

main/Main.hs

@@ -10,9 +10,10 @@ import           Control.Comonad                ( extract )
 import qualified Control.DeepSeq               as Deep
 import qualified Control.Exception             as Exc
 import           GHC.Err                        ( errorWithoutStackTrace )
+import           Control.Monad.Free
+import           Control.Monad.Ref              ( MonadRef(readRef) )
 import           Control.Monad.Catch
 import           System.IO                      ( hPutStrLn, getContents )
-import           Control.Monad.Free
 import qualified Data.HashMap.Lazy             as M
 import qualified Data.Map                      as Map
 import           Data.Maybe                     ( fromJust )
@@ -27,9 +28,9 @@ import           Nix.Json
 import           Nix.Options.Parser
 import           Nix.Standard
 import           Nix.Thunk.Basic
-import qualified Nix.Type.Env                  as Env
+import           Nix.Type.Env                   ( Env(..) )
+import           Nix.Type.Type                  ( Scheme )
 import qualified Nix.Type.Infer                as HM
-import           Nix.Var
 import           Nix.Value.Monad
 import           Options.Applicative     hiding ( ParserResult(..) )
 import           Prettyprinter           hiding ( list )
@@ -43,7 +44,7 @@ main :: IO ()
 main =
   do
     time <- getCurrentTime
-    opts <- execParser (nixOptionsInfo time)
+    opts <- execParser $ nixOptionsInfo time
 
     runWithBasicEffectsIO opts $ execContentsFilesOrRepl opts
 
@@ -103,9 +104,9 @@ main =
               either
                 (\ err -> errorWithoutStackTrace $ "Type error: " <> PS.ppShow err)
                 (\ ty  -> liftIO $ putStrLn $ "Type of expression: " <> PS.ppShow
-                  (fromJust $ Map.lookup "it" $ Env.types ty)
+                  (fromJust $ Map.lookup "it" (coerce ty :: Map Text [Scheme]))
                 )
-                (HM.inferTop Env.empty [("it", stripAnnotation expr')])
+                (HM.inferTop mempty [("it", stripAnnotation expr')])
 
                 -- liftIO $ putStrLn $ runST $
                 --     runLintM opts . renderSymbolic =<< lint opts expr
@@ -177,23 +178,26 @@ main =
             xs <-
               traverse
                 (\ (k, nv) ->
+                  (k, ) <$>
                   free
                     (\ (StdThunk (extract -> Thunk _ _ ref)) ->
                       do
                         let
                           path         = prefix <> k
                           (_, descend) = filterEntry path k
 
-                        val <- readVar @(StandardT (StdIdT IO)) ref
-                        case val of
-                          Computed _    -> pure (k, Nothing)
-                          _ ->
-                            bool
-                              (pure (k, Nothing))
-                              ((k, ) <$> forceEntry path nv)
-                              descend
+                        val <- readRef @(StandardT (StdIdT IO)) ref
+                        bool
+                          (pure Nothing)
+                          (forceEntry path nv)
+                          (descend &&
+                           deferred
+                            (const False)
+                            (const True)
+                            val
+                          )
                     )
-                    (\ v -> pure (k, pure $ Free v))
+                    (pure . pure . Free)
                     nv
                 )
                 (sortWith fst $ M.toList s)
@@ -278,7 +282,4 @@ main =
         do
           putStrLn $ "Wrote sifted expression tree to " <> path
           writeFile path $ show $ prettyNix $ stripAnnotation expr'
-      either
-        throwM
-        pure
-        eres
+      either throwM pure eres

main/Repl.hs

@@ -208,7 +208,7 @@ exec update source = do
       -- import qualified Nix.Type.Env                  as Env
       -- import           Nix.Type.Infer
       --
-      -- let tyctx' = inferTop Env.empty [("repl", stripAnnotation expr)]
+      -- let tyctx' = inferTop mempty [("repl", stripAnnotation expr)]
       -- liftIO $ print tyctx'
 
       mVal <- lift $ lift $ try $ pushScope (replCtx st) (evalExprLoc expr)
@@ -225,7 +225,7 @@ exec update source = do
 
             -- If the result value is a set, update our context with it
             case val of
-              NVSet xs _ -> put st { replCtx = Data.HashMap.Lazy.union xs (replCtx st) }
+              NVSet xs _ -> put st { replCtx = xs <> replCtx st }
               _          -> pass
 
           pure $ pure val

src/Nix.hs

@@ -60,7 +60,7 @@ nixEval
   -> Maybe FilePath
   -> Fix g
   -> m a
-nixEval transform alg mpath = withNixContext mpath . adi alg transform
+nixEval transform alg mpath = withNixContext mpath . adi transform alg
 
 -- | Evaluate a nix expression in the default context
 nixEvalExpr

src/Nix/Atoms.hs

@@ -3,9 +3,7 @@
 
 module Nix.Atoms where
 
-#ifdef MIN_VERSION_serialise
 import           Codec.Serialise                ( Serialise )
-#endif
 
 import           Data.Data                      ( Data)
 import           Data.Fixed                     ( mod' )
@@ -48,9 +46,7 @@ data NAtom
     , Hashable
     )
 
-#ifdef MIN_VERSION_serialise
 instance Serialise NAtom
-#endif
 
 instance Binary NAtom
 instance ToJSON NAtom