Merge #983: Parser: org, clean-up, refactor, upds, API breakage

* `Parser`:
  * `(nixExpr -> nixExprAlgebra)`.
  * `(nixTopLevelForm -> nixExpr)`.
  * rm `symbol` from export - they are too core - solving them away inside Parser is crucial, while also too simple `symbol x = char x <* whiteSpace` that people can look-it up/infer themselves, `whiteSpace` so far is requires to be exported, until the situation with Windows `\r\n` gets clearer (when the situation would be properly solved - that export would be superfluous).
  * use of `takeWhile{,1}P`, which strongly optimizes (magnitudes) the according actions in the parser.
  * module organization.
  * all other refactors.

Author: Anton-Latukha

default.nix

@@ -93,7 +93,7 @@
 #   , nixos-20.03  # Last stable release, gets almost no updates to recipes, gets only required backports
 #   ...
 #   }
-, rev ? "20887e4bbfdae3aed6bfa1f53ddf138ee325515e"
+, rev ? "9df2cb074d72ea80ac9fd225b29060c8cf13dd39"
 
 , pkgs ?
     if builtins.compareVersions builtins.nixVersion "2.0" > 0
@@ -192,8 +192,6 @@ let
 
       semialign = super.semialign_1_2;
       relude = super.relude_1_0_0_1;
-      hnix-store-core = super.hnix-store-core_0_5_0_0;
-      hnix-store-remote = super.hnix-store-remote_0_5_0_0;
 
     };
 

hnix.cabal

@@ -432,7 +432,7 @@ library
     , lens-family-core >= 1.2.2 && < 2.2
     , lens-family-th >= 0.5.0 && < 0.6
     , logict >= 0.6.0 && < 0.7 || >= 0.7.0.2 && < 0.8
-    , megaparsec >= 7.0 && < 9.1
+    , megaparsec >= 7.0 && < 9.2
     , monad-control >= 1.0.2 && < 1.1
     , monadlist >= 0.0.2 && < 0.1
     , mtl >= 2.2.2 && < 2.3

src/Nix/Atoms.hs

@@ -11,6 +11,7 @@ import           Data.Binary                    ( Binary )
 import           Data.Aeson.Types               ( FromJSON
                                                 , ToJSON
                                                 )
+--  2021-08-01: NOTE: Check the order efficience of NAtom constructors.
 
 -- | Atoms are values that evaluate to themselves.
 -- In other words - this is a constructors that are literals in Nix.

src/Nix/Eval.hs

@@ -151,12 +151,12 @@ eval (NList l           ) =
 
 eval (NSet NonRecursive binds) =
   do
-    attrSet <- evalBinds False $ desugarBinds (eval . NSet NonRecursive) binds
+    attrSet <- evalBinds False $ desugarBinds (eval . NSet mempty) binds
     toValue attrSet
 
 eval (NSet Recursive binds) =
   do
-    attrSet <- evalBinds True $ desugarBinds (eval . NSet NonRecursive) binds
+    attrSet <- evalBinds True $ desugarBinds (eval . NSet mempty) binds
     toValue attrSet
 
 eval (NLet binds body    ) =

src/Nix/Exec.hs

@@ -141,7 +141,7 @@ currentPos :: forall e m . (MonadReader e m, Has e SrcSpan) => m SrcSpan
 currentPos = asks $ view hasLens
 
 wrapExprLoc :: SrcSpan -> NExprLocF r -> NExprLoc
-wrapExprLoc span x = Fix $ Fix (NSymAnnF span "<?>") <$ x
+wrapExprLoc span x = Fix $ NSymAnn span "<?>" <$ x
 {-# inline wrapExprLoc #-}
 
 --  2021-01-07: NOTE: This instance belongs to be beside MonadEval type class.
@@ -155,7 +155,7 @@ instance MonadNix e t f m => MonadEval (NValue t f m) m where
     scope <- currentScopes
     evalError @(NValue t f m) $ SynHole $
       SynHoleInfo
-        { _synHoleInfo_expr  = Fix $ NSynHoleAnnF span name
+        { _synHoleInfo_expr  = NSynHoleAnn span name
         , _synHoleInfo_scope = scope
         }
 

src/Nix/Expr/Shorthands.hs

@@ -135,7 +135,7 @@ mkRecSet = mkSet Recursive
 --
 -- > { .. }
 mkNonRecSet :: [Binding NExpr] -> NExpr
-mkNonRecSet = mkSet NonRecursive
+mkNonRecSet = mkSet mempty
 
 -- | General set builder function.
 mkSet :: Recursivity -> [Binding NExpr] -> NExpr

src/Nix/Expr/Strings.hs

@@ -22,8 +22,8 @@ mergePlain (x                 : xs) = x : mergePlain xs
 
 -- | Remove 'Plain' values equal to 'mempty', as they don't have any
 -- informational content.
-removePlainEmpty :: [Antiquoted Text r] -> [Antiquoted Text r]
-removePlainEmpty = filter f where
+removeEmptyPlains :: [Antiquoted Text r] -> [Antiquoted Text r]
+removeEmptyPlains = filter f where
   f (Plain x) = x /= mempty
   f _         = True
 
@@ -60,7 +60,7 @@ stripIndent [] = Indented 0 mempty
 stripIndent xs =
   Indented
     minIndent
-    (removePlainEmpty $
+    (removeEmptyPlains $
       mergePlain $
         (snd <$>) $
           dropWhileEnd

src/Nix/Expr/Types.hs

@@ -448,6 +448,12 @@ data Recursivity
     , Show, Read, Hashable
     )
 
+instance Semigroup Recursivity where
+  (<>) NonRecursive NonRecursive = NonRecursive
+  (<>) _ _ = Recursive
+
+instance Monoid Recursivity where
+  mempty = NonRecursive
 
 -- ** data NUnaryOp
 
@@ -712,7 +718,7 @@ ekey keys pos f e@(Fix x) | (NSet NonRecursive xs, ann) <- fromNExpr x =
         e
         (\ v ->
           let entry = NamedVar (StaticKey <$> keys) v pos in
-          Fix $ toNExpr ( NSet NonRecursive $ [entry] <> xs, ann )
+          Fix $ toNExpr ( NSet mempty $ [entry] <> xs, ann )
         )
       <$>
         f Nothing

src/Nix/Expr/Types/Annotated.hs

@@ -56,8 +56,8 @@ data SrcSpan = SrcSpan
 instance Semigroup SrcSpan where
   s1 <> s2 =
     SrcSpan
-      ((min `on` spanBegin) s1 s2)
-      ((max `on` spanEnd  ) s1 s2)
+      (on min spanBegin s1 s2)
+      (on max spanEnd   s1 s2)
 
 instance Binary SrcSpan
 instance ToJSON SrcSpan
@@ -67,6 +67,7 @@ instance Serialise SrcSpan
 
 -- * data type @Ann@
 
+--  2021-08-02: NOTE: Annotation needs to be after what is annotated.
 -- | A type constructor applied to a type along with an annotation
 --
 -- Intended to be used with 'Fix':