Re CLC #300 - Specify fmap for NonEmpty as map

See:
* haskell/core-libraries-committee#300

Seeks to:
* move existing instances for NonEmpty (except of Eq and Ord) out of GHC.Internal.Base into new GHC.Internal.Data.NonEmpty (to avoid otherwise unavoidable cycles in the module graph);
* move map out of Data.List.NonEmpty (base package) into GHC.Internal.Data.NonEmpty;
* define fmap as map for NonEmpty instance of Functor, avoiding code duplication;
* re-export map from existing GHC.Internal.Data.List.NonEmpty; and
* re-export map from Data.List.NonEmpty (base package);

without breaking anything in the GHC repository.

Various tests *.stdout and *.stderr files are amended also.

Author: mpilgrem

libraries/base/changelog.md

@@ -8,6 +8,7 @@
     ([GHC #25066](https://gitlab.haskell.org/ghc/ghc/-/issues/25066), [CLC proposal #290](https://github.com/haskell/core-libraries-committee/issues/290))
   * `Data.List.NonEmpty.{init,last,tails1}` are now defined using only total functions (rather than partial ones). ([CLC proposal #293](https://github.com/haskell/core-libraries-committee/issues/293))
   * `Data.List.NonEmpty` functions now have the same laziness as their `Data.List` counterparts (i.e. make them more strict than they currently are) ([CLC proposal #107](https://github.com/haskell/core-libraries-committee/issues/107))
+  * `instance Functor NonEmpty` is now specified using `map` (rather than duplicating code). ([CLC proposal #300](https://github.com/haskell/core-libraries-committee/issues/300))
 
 ## 4.21.0.0 *TBA*
   * Introduce `Data.Bounded` module exporting the `Bounded` typeclass (finishing [CLC proposal #208](https://github.com/haskell/core-libraries-committee/issues/208))

libraries/base/src/Data/List/NonEmpty.hs

@@ -123,7 +123,7 @@ import qualified GHC.Internal.Data.Foldable       as Foldable
 import           GHC.Internal.Data.Function       (on)
 import           GHC.Internal.Data.Ord            (comparing)
 import           GHC.Internal.Stack.Types     (HasCallStack)
-import           GHC.Internal.Data.List.NonEmpty
+import           GHC.Internal.Data.List.NonEmpty (NonEmpty (..), map, zip, zipWith)
 
 infixr 5 <|
 
@@ -290,10 +290,6 @@ toList (a :| as) = a : as
 lift :: Foldable f => ([a] -> [b]) -> f a -> NonEmpty b
 lift f = fromList . f . Foldable.toList
 
--- | Map a function over a 'NonEmpty' stream.
-map :: (a -> b) -> NonEmpty a -> NonEmpty b
-map f (a :| as) = f a :| fmap f as
-
 -- | The 'inits' function takes a stream @xs@ and returns all the
 -- finite prefixes of @xs@, starting with the shortest. The result is
 -- 'NonEmpty' because the result always contains the empty list as the first

libraries/base/src/Data/Semigroup.hs

@@ -105,7 +105,7 @@ module Data.Semigroup (
   , ArgMax
   ) where
 
-import           GHC.Internal.Base hiding (Any)
+import           GHC.Internal.Base hiding (Any, NonEmpty(..))
 import           GHC.Internal.Enum
 import           GHC.Internal.Show
 import           GHC.Internal.Read
@@ -116,6 +116,7 @@ import           Data.Bifoldable
 import           Data.Bifunctor
 import           Data.Bitraversable
 import           GHC.Internal.Data.Foldable
+import           GHC.Internal.Data.NonEmpty (NonEmpty(..))
 import           GHC.Internal.Data.Traversable
 import           GHC.Internal.Data.Semigroup.Internal
 import           GHC.Internal.Control.Monad.Fix

libraries/base/src/GHC/Base.hs

@@ -138,7 +138,8 @@ module GHC.Base
     , divModInt#, divModInt8#, divModInt16#, divModInt32#
     ) where
 
-import GHC.Internal.Base
+import GHC.Internal.Base hiding ( NonEmpty(..) )
+import GHC.Internal.Data.NonEmpty ( NonEmpty(..) )
 import GHC.Prim hiding
   (
   -- Hide dataToTag# ops because they are expected to break for

libraries/ghc-internal/ghc-internal.cabal.in

@@ -152,6 +152,7 @@ Library
         GHC.Internal.Data.List.NonEmpty
         GHC.Internal.Data.Maybe
         GHC.Internal.Data.Monoid
+        GHC.Internal.Data.NonEmpty
         GHC.Internal.Data.OldList
         GHC.Internal.Data.Ord
         GHC.Internal.Data.Proxy

libraries/ghc-internal/src/GHC/Internal/Base.hs

@@ -17,7 +17,7 @@ GHC.Prim        Has no implementation.  It defines built-in things, and
                 copied to make GHC.Prim.hi
 
 GHC.Internal.Base        Classes: Eq, Ord, Functor, Monad
-                Types:   List, (), Int, Bool, Ordering, Char, String
+                Types:   List, (), Int, Bool, Ordering, Char, String, NonEmpty
 
 GHC.Internal.Data.Tuple      Types: tuples, plus instances for GHC.Internal.Base classes
 
@@ -29,6 +29,13 @@ GHC.Internal.Data.Maybe      Type: Maybe, plus instances for GHC.Internal.Base c
 
 GHC.Internal.List        List functions
 
+GHC.Internal.Data.NonEmpty   Orphan instances for GHC.Internal.Base.NonEmpty of
+                             GHC.Internal.Base classes (other than Eq and Ord)
+                             plus function map
+
+GHC.Internal.Data.List.NonEmpty   Re-export GHC.Internal.Data.NonEmpty plus
+                                  functions zip and zipWith
+
 GHC.Internal.Num         Class: Num, plus instances for Int
                 Type:  Integer, plus instances for all classes so far (Eq, Ord, Num, Show)
 
@@ -753,12 +760,6 @@ needed to make foldr/build forms efficient are turned off, we'll get reasonably
 efficient translations anyway.
 -}
 
--- | @since base-4.9.0.0
-instance Semigroup (NonEmpty a) where
-        (a :| as) <> bs = a :| (as ++ toList bs)
-          where
-            toList (c :| cs) = c : cs
-
 -- | @since base-4.9.0.0
 instance Semigroup b => Semigroup (a -> b) where
         f <> g = \x -> f x <> g x
@@ -1709,27 +1710,6 @@ data NonEmpty a = a :| [a]
            , Ord -- ^ @since base-4.9.0.0
            )
 
--- | @since base-4.9.0.0
-instance Functor NonEmpty where
-  fmap f (a :| as) = f a :| fmap f as
-  b <$ (_ :| as)   = b   :| (b <$ as)
-
--- | @since base-4.9.0.0
-instance Applicative NonEmpty where
-  pure a = a :| []
-  (<*>) = ap
-  liftA2 = liftM2
-
--- | @since base-4.9.0.0
-instance Monad NonEmpty where
-  (a :| as) >>= f =
-    case f a of
-      b :| bs -> b :| (bs ++ bs')
-    where
-      bs' = as >>= toList . f
-      toList (c :| cs) = c : cs
-
-
 ----------------------------------------------
 -- The list type
 

libraries/ghc-internal/src/GHC/Internal/Control/Monad/Fix.hs

@@ -32,9 +32,10 @@ import GHC.Internal.Data.Function ( fix )
 import GHC.Internal.Data.Maybe
 import GHC.Internal.Data.Monoid ( Monoid, Dual(..), Sum(..), Product(..)
                    , First(..), Last(..), Alt(..), Ap(..) )
+import GHC.Internal.Data.NonEmpty ( NonEmpty(..) )
 import GHC.Internal.Data.Ord ( Down(..) )
 import GHC.Internal.Data.Tuple ( Solo(..), snd )
-import GHC.Internal.Base ( Monad, NonEmpty(..), errorWithoutStackTrace, (.) )
+import GHC.Internal.Base ( Monad, errorWithoutStackTrace, (.) )
 import GHC.Internal.Generics
 import GHC.Internal.List ( head, drop )
 import GHC.Internal.Control.Monad.ST.Imp

libraries/ghc-internal/src/GHC/Internal/Control/Monad/Zip.hs

@@ -22,9 +22,9 @@ import GHC.Internal.Control.Monad (liftM, liftM2, Monad(..))
 import GHC.Internal.Data.Functor.Identity
 import qualified GHC.Internal.Data.Functor
 import GHC.Internal.Data.Monoid
+import GHC.Internal.Data.NonEmpty ( NonEmpty(..) )
 import GHC.Internal.Data.Ord ( Down(..) )
 import GHC.Internal.Data.Proxy
-import GHC.Internal.Base (NonEmpty(..))
 --import qualified Data.List.NonEmpty as NE
 import GHC.Internal.Generics
 import qualified GHC.Internal.Data.List.NonEmpty as NE

libraries/ghc-internal/src/GHC/Internal/Data/Data.hs

@@ -115,11 +115,12 @@ import GHC.Internal.Data.Either
 import GHC.Internal.Data.Eq
 import GHC.Internal.Data.Maybe
 import GHC.Internal.Data.Monoid
+import GHC.Internal.Data.NonEmpty ( NonEmpty(..) )
 import GHC.Internal.Data.Ord
 import GHC.Internal.Data.List (findIndex)
 import GHC.Internal.Data.Typeable
 import GHC.Internal.Data.Version( Version(..) )
-import GHC.Internal.Base hiding (Any, IntRep, FloatRep)
+import GHC.Internal.Base hiding (Any, IntRep, FloatRep, NonEmpty(..))
 import GHC.Internal.List
 import GHC.Internal.Num
 import GHC.Internal.Read

libraries/ghc-internal/src/GHC/Internal/Data/Foldable.hs

@@ -1529,4 +1529,3 @@ the number of elements combined).  The `mconcat` implementations for `Text` and
 `ByteString` preallocate the required storage, and then combine all the list
 elements in a single pass.
 -}
-