Remove an unused import

[ghc-base.git] / GHC / Base.lhs

diff --git a/GHC/Base.lhs b/GHC/Base.lhs
index 32bf498..341a630 100644 (file)
--- a/GHC/Base.lhs
+++ b/GHC/Base.lhs
@@ -3,68 +3,67 @@
 The overall structure of the GHC Prelude is a bit tricky.
 
   a) We want to avoid "orphan modules", i.e. ones with instance
 The overall structure of the GHC Prelude is a bit tricky.
 
   a) We want to avoid "orphan modules", i.e. ones with instance

-       decls that don't belong either to a tycon or a class
-       defined in the same module
+        decls that don't belong either to a tycon or a class
+        defined in the same module

 
   b) We want to avoid giant modules
 
 So the rough structure is as follows, in (linearised) dependency order
 
 
 
   b) We want to avoid giant modules
 
 So the rough structure is as follows, in (linearised) dependency order
 
 

-GHC.Prim               Has no implementation.  It defines built-in things, and
-               by importing it you bring them into scope.
-               The source file is GHC.Prim.hi-boot, which is just
-               copied to make GHC.Prim.hi
+GHC.Prim                Has no implementation.  It defines built-in things, and
+                by importing it you bring them into scope.
+                The source file is GHC.Prim.hi-boot, which is just
+                copied to make GHC.Prim.hi

 
 

-GHC.Base       Classes: Eq, Ord, Functor, Monad
-               Types:   list, (), Int, Bool, Ordering, Char, String
+GHC.Base        Classes: Eq, Ord, Functor, Monad
+                Types:   list, (), Int, Bool, Ordering, Char, String

 
 

-Data.Tup       Types: tuples, plus instances for GHC.Base classes
+Data.Tuple      Types: tuples, plus instances for GHC.Base classes

 
 

-GHC.Show       Class: Show, plus instances for GHC.Base/GHC.Tup types
+GHC.Show        Class: Show, plus instances for GHC.Base/GHC.Tup types

 
 

-GHC.Enum       Class: Enum,  plus instances for GHC.Base/GHC.Tup types
+GHC.Enum        Class: Enum,  plus instances for GHC.Base/GHC.Tup types

 
 

-Data.Maybe     Type: Maybe, plus instances for GHC.Base classes
+Data.Maybe      Type: Maybe, plus instances for GHC.Base classes

 
 

-GHC.Num                Class: Num, plus instances for Int
-               Type:  Integer, plus instances for all classes so far (Eq, Ord, Num, Show)
+GHC.List        List functions

 
 

-               Integer is needed here because it is mentioned in the signature
-               of 'fromInteger' in class Num
+GHC.Num         Class: Num, plus instances for Int
+                Type:  Integer, plus instances for all classes so far (Eq, Ord, Num, Show)

 
 

-GHC.Real       Classes: Real, Integral, Fractional, RealFrac
-                        plus instances for Int, Integer
-               Types:  Ratio, Rational
-                       plus intances for classes so far
+                Integer is needed here because it is mentioned in the signature
+                of 'fromInteger' in class Num

 
 

-               Rational is needed here because it is mentioned in the signature
-               of 'toRational' in class Real
+GHC.Real        Classes: Real, Integral, Fractional, RealFrac
+                         plus instances for Int, Integer
+                Types:  Ratio, Rational
+                        plus intances for classes so far

 
 

-Ix             Classes: Ix, plus instances for Int, Bool, Char, Integer, Ordering, tuples
+                Rational is needed here because it is mentioned in the signature
+                of 'toRational' in class Real

 
 

-GHC.Arr                Types: Array, MutableArray, MutableVar
+GHC.ST  The ST monad, instances and a few helper functions

 
 

-               Does *not* contain any ByteArray stuff (see GHC.ByteArr)
-               Arrays are used by a function in GHC.Float
+Ix              Classes: Ix, plus instances for Int, Bool, Char, Integer, Ordering, tuples

 
 

-GHC.Float      Classes: Floating, RealFloat
-               Types:   Float, Double, plus instances of all classes so far
+GHC.Arr         Types: Array, MutableArray, MutableVar

 
 

-               This module contains everything to do with floating point.
-               It is a big module (900 lines)
-               With a bit of luck, many modules can be compiled without ever reading GHC.Float.hi
+                Arrays are used by a function in GHC.Float

 
 

-GHC.ByteArr    Types: ByteArray, MutableByteArray
-               
-               We want this one to be after GHC.Float, because it defines arrays
-               of unboxed floats.
+GHC.Float       Classes: Floating, RealFloat
+                Types:   Float, Double, plus instances of all classes so far
+
+                This module contains everything to do with floating point.
+                It is a big module (900 lines)
+                With a bit of luck, many modules can be compiled without ever reading GHC.Float.hi

 
 
 Other Prelude modules are much easier with fewer complex dependencies.
 
 \begin{code}
 
 
 Other Prelude modules are much easier with fewer complex dependencies.
 
 \begin{code}

-{-# OPTIONS_GHC -fno-implicit-prelude #-}
+{-# OPTIONS_GHC -XNoImplicitPrelude #-}
+{-# OPTIONS_HADDOCK hide #-}

 -----------------------------------------------------------------------------
 -- |
 -- Module      :  GHC.Base
 -----------------------------------------------------------------------------
 -- |
 -- Module      :  GHC.Base

@@ -83,13 +82,19 @@ Other Prelude modules are much easier with fewer complex dependencies.
 
 -- #hide
 module GHC.Base
 
 -- #hide
 module GHC.Base

-       (
-       module GHC.Base,
-       module GHC.Prim,        -- Re-export GHC.Prim and GHC.Err, to avoid lots
-       module GHC.Err          -- of people having to import it explicitly
+        (
+        module GHC.Base,
+        module GHC.Bool,
+        module GHC.Generics,
+        module GHC.Ordering,
+        module GHC.Prim,        -- Re-export GHC.Prim and GHC.Err, to avoid lots
+        module GHC.Err          -- of people having to import it explicitly

   ) 
   ) 

-       where
+        where

 
 

+import GHC.Bool
+import GHC.Generics
+import GHC.Ordering

 import GHC.Prim
 import {-# SOURCE #-} GHC.Err
 
 import GHC.Prim
 import {-# SOURCE #-} GHC.Err
 

@@ -101,15 +106,15 @@ infixr 2  ||
 infixl 1  >>, >>=
 infixr 0  $
 
 infixl 1  >>, >>=
 infixr 0  $
 

-default ()             -- Double isn't available yet
+default ()              -- Double isn't available yet

 \end{code}
 
 
 %*********************************************************
 \end{code}
 
 
 %*********************************************************

-%*                                                     *
+%*                                                      *

 \subsection{DEBUGGING STUFF}
 %*  (for use when compiling GHC.Base itself doesn't work)
 \subsection{DEBUGGING STUFF}
 %*  (for use when compiling GHC.Base itself doesn't work)

-%*                                                     *
+%*                                                      *

 %*********************************************************
 
 \begin{code}
 %*********************************************************
 
 \begin{code}

@@ -142,9 +147,9 @@ unpackCStringUtf8# a = error "urk"
 
 
 %*********************************************************
 
 
 %*********************************************************

-%*                                                     *
+%*                                                      *

 \subsection{Standard classes @Eq@, @Ord@}
 \subsection{Standard classes @Eq@, @Ord@}

-%*                                                     *
+%*                                                      *

 %*********************************************************
 
 \begin{code}
 %*********************************************************
 
 \begin{code}

@@ -157,10 +162,10 @@ unpackCStringUtf8# a = error "urk"
 -- Minimal complete definition: either '==' or '/='.
 --
 class  Eq a  where
 -- Minimal complete definition: either '==' or '/='.
 --
 class  Eq a  where

-    (==), (/=)          :: a -> a -> Bool
+    (==), (/=)           :: a -> a -> Bool

 
 

-    x /= y              = not (x == y)
-    x == y              = not (x /= y)
+    x /= y               = not (x == y)
+    x == y               = not (x /= y)

 
 -- | The 'Ord' class is used for totally ordered datatypes.
 --
 
 -- | The 'Ord' class is used for totally ordered datatypes.
 --

@@ -174,32 +179,32 @@ class  Eq a  where
 -- Using 'compare' can be more efficient for complex types.
 --
 class  (Eq a) => Ord a  where
 -- Using 'compare' can be more efficient for complex types.
 --
 class  (Eq a) => Ord a  where

-    compare             :: a -> a -> Ordering
+    compare              :: a -> a -> Ordering

     (<), (<=), (>), (>=) :: a -> a -> Bool
     (<), (<=), (>), (>=) :: a -> a -> Bool

-    max, min            :: a -> a -> a
+    max, min             :: a -> a -> a

 
     compare x y
 
     compare x y

-       | x == y    = EQ
-       | x <= y    = LT        -- NB: must be '<=' not '<' to validate the
-                               -- above claim about the minimal things that
-                               -- can be defined for an instance of Ord
-       | otherwise = GT
+        | x == y    = EQ
+        | x <= y    = LT        -- NB: must be '<=' not '<' to validate the
+                                -- above claim about the minimal things that
+                                -- can be defined for an instance of Ord
+        | otherwise = GT

 
 

-    x <         y = case compare x y of { LT -> True;  _other -> False }
+    x <  y = case compare x y of { LT -> True;  _other -> False }

     x <= y = case compare x y of { GT -> False; _other -> True }
     x <= y = case compare x y of { GT -> False; _other -> True }

-    x >         y = case compare x y of { GT -> True;  _other -> False }
+    x >  y = case compare x y of { GT -> True;  _other -> False }

     x >= y = case compare x y of { LT -> False; _other -> True }
 
     x >= y = case compare x y of { LT -> False; _other -> True }
 

-       -- These two default methods use '<=' rather than 'compare'
-       -- because the latter is often more expensive
+        -- These two default methods use '<=' rather than 'compare'
+        -- because the latter is often more expensive

     max x y = if x <= y then y else x
     min x y = if x <= y then x else y
 \end{code}
 
 %*********************************************************
     max x y = if x <= y then y else x
     min x y = if x <= y then x else y
 \end{code}
 
 %*********************************************************

-%*                                                     *
+%*                                                      *

 \subsection{Monadic classes @Functor@, @Monad@ }
 \subsection{Monadic classes @Functor@, @Monad@ }

-%*                                                     *
+%*                                                      *

 %*********************************************************
 
 \begin{code}
 %*********************************************************
 
 \begin{code}

@@ -247,15 +252,15 @@ class  Monad m  where
     -- by the first, like sequencing operators (such as the semicolon)
     -- in imperative languages.
     (>>)        :: forall a b. m a -> m b -> m b
     -- by the first, like sequencing operators (such as the semicolon)
     -- in imperative languages.
     (>>)        :: forall a b. m a -> m b -> m b

-       -- Explicit for-alls so that we know what order to
-       -- give type arguments when desugaring
+        -- Explicit for-alls so that we know what order to
+        -- give type arguments when desugaring

 
     -- | Inject a value into the monadic type.
     return      :: a -> m a
     -- | Fail with a message.  This operation is not part of the
     -- mathematical definition of a monad, but is invoked on pattern-match
     -- failure in a @do@ expression.
 
     -- | Inject a value into the monadic type.
     return      :: a -> m a
     -- | Fail with a message.  This operation is not part of the
     -- mathematical definition of a monad, but is invoked on pattern-match
     -- failure in a @do@ expression.

-    fail       :: String -> m a
+    fail        :: String -> m a

 
     m >> k      = m >>= \_ -> k
     fail s      = error s
 
     m >> k      = m >>= \_ -> k
     fail s      = error s

@@ -263,14 +268,14 @@ class  Monad m  where
 
 
 %*********************************************************
 
 
 %*********************************************************

-%*                                                     *
+%*                                                      *

 \subsection{The list type}
 \subsection{The list type}

-%*                                                     *
+%*                                                      *

 %*********************************************************
 
 \begin{code}
 data [] a = [] | a : [a]  -- do explicitly: deriving (Eq, Ord)
 %*********************************************************
 
 \begin{code}
 data [] a = [] | a : [a]  -- do explicitly: deriving (Eq, Ord)

-                         -- to avoid weird names like con2tag_[]#
+                          -- to avoid weird names like con2tag_[]#

 
 
 instance (Eq a) => Eq [a] where
 
 
 instance (Eq a) => Eq [a] where

@@ -295,14 +300,14 @@ instance  Monad []  where
     m >>= k             = foldr ((++) . k) [] m
     m >> k              = foldr ((++) . (\ _ -> k)) [] m
     return x            = [x]
     m >>= k             = foldr ((++) . k) [] m
     m >> k              = foldr ((++) . (\ _ -> k)) [] m
     return x            = [x]

-    fail _             = []
+    fail _              = []

 \end{code}
 
 A few list functions that appear here because they are used here.
 The rest of the prelude list functions are in GHC.List.
 
 ----------------------------------------------
 \end{code}
 
 A few list functions that appear here because they are used here.
 The rest of the prelude list functions are in GHC.List.
 
 ----------------------------------------------

---     foldr/build/augment
+--      foldr/build/augment

 ----------------------------------------------
   
 \begin{code}
 ----------------------------------------------
   
 \begin{code}

@@ -318,34 +323,34 @@ foldr            :: (a -> b -> b) -> b -> [a] -> b
 {-# INLINE [0] foldr #-}
 -- Inline only in the final stage, after the foldr/cons rule has had a chance
 foldr k z xs = go xs
 {-# INLINE [0] foldr #-}
 -- Inline only in the final stage, after the foldr/cons rule has had a chance
 foldr k z xs = go xs

-            where
-              go []     = z
-              go (y:ys) = y `k` go ys
+             where
+               go []     = z
+               go (y:ys) = y `k` go ys

 
 -- | A list producer that can be fused with 'foldr'.
 -- This function is merely
 --
 
 -- | A list producer that can be fused with 'foldr'.
 -- This function is merely
 --

--- >   build g = g (:) []
+-- >    build g = g (:) []

 --
 -- but GHC's simplifier will transform an expression of the form
 -- @'foldr' k z ('build' g)@, which may arise after inlining, to @g k z@,
 -- which avoids producing an intermediate list.
 
 --
 -- but GHC's simplifier will transform an expression of the form
 -- @'foldr' k z ('build' g)@, which may arise after inlining, to @g k z@,
 -- which avoids producing an intermediate list.
 

-build  :: forall a. (forall b. (a -> b -> b) -> b -> b) -> [a]
+build   :: forall a. (forall b. (a -> b -> b) -> b -> b) -> [a]

 {-# INLINE [1] build #-}
 {-# INLINE [1] build #-}

-       -- The INLINE is important, even though build is tiny,
-       -- because it prevents [] getting inlined in the version that
-       -- appears in the interface file.  If [] *is* inlined, it
-       -- won't match with [] appearing in rules in an importing module.
-       --
-       -- The "1" says to inline in phase 1
+        -- The INLINE is important, even though build is tiny,
+        -- because it prevents [] getting inlined in the version that
+        -- appears in the interface file.  If [] *is* inlined, it
+        -- won't match with [] appearing in rules in an importing module.
+        --
+        -- The "1" says to inline in phase 1

 
 build g = g (:) []
 
 -- | A list producer that can be fused with 'foldr'.
 -- This function is merely
 --
 
 build g = g (:) []
 
 -- | A list producer that can be fused with 'foldr'.
 -- This function is merely
 --

--- >   augment g xs = g (:) xs
+-- >    augment g xs = g (:) xs

 --
 -- but GHC's simplifier will transform an expression of the form
 -- @'foldr' k z ('augment' g xs)@, which may arise after inlining, to
 --
 -- but GHC's simplifier will transform an expression of the form
 -- @'foldr' k z ('augment' g xs)@, which may arise after inlining, to

@@ -356,42 +361,42 @@ augment :: forall a. (forall b. (a->b->b) -> b -> b) -> [a] -> [a]
 augment g xs = g (:) xs
 
 {-# RULES
 augment g xs = g (:) xs
 
 {-# RULES

-"fold/build"   forall k z (g::forall b. (a->b->b) -> b -> b) . 
-               foldr k z (build g) = g k z
+"fold/build"    forall k z (g::forall b. (a->b->b) -> b -> b) . 
+                foldr k z (build g) = g k z

 
 "foldr/augment" forall k z xs (g::forall b. (a->b->b) -> b -> b) . 
 
 "foldr/augment" forall k z xs (g::forall b. (a->b->b) -> b -> b) . 

-               foldr k z (augment g xs) = g k (foldr k z xs)
+                foldr k z (augment g xs) = g k (foldr k z xs)

 
 

-"foldr/id"                       foldr (:) [] = \x->x
-"foldr/app"            [1] forall xs ys. foldr (:) ys xs = xs ++ ys
-       -- Only activate this from phase 1, because that's
-       -- when we disable the rule that expands (++) into foldr
+"foldr/id"                        foldr (:) [] = \x  -> x
+"foldr/app"     [1] forall ys. foldr (:) ys = \xs -> xs ++ ys
+        -- Only activate this from phase 1, because that's
+        -- when we disable the rule that expands (++) into foldr

 
 -- The foldr/cons rule looks nice, but it can give disastrously
 -- bloated code when commpiling
 
 -- The foldr/cons rule looks nice, but it can give disastrously
 -- bloated code when commpiling

---     array (a,b) [(1,2), (2,2), (3,2), ...very long list... ]
+--      array (a,b) [(1,2), (2,2), (3,2), ...very long list... ]

 -- i.e. when there are very very long literal lists
 -- So I've disabled it for now. We could have special cases
 -- for short lists, I suppose.
 -- i.e. when there are very very long literal lists
 -- So I've disabled it for now. We could have special cases
 -- for short lists, I suppose.

--- "foldr/cons"        forall k z x xs. foldr k z (x:xs) = k x (foldr k z xs)
+-- "foldr/cons" forall k z x xs. foldr k z (x:xs) = k x (foldr k z xs)

 
 

-"foldr/single" forall k z x. foldr k z [x] = k x z
-"foldr/nil"    forall k z.   foldr k z []  = z 
+"foldr/single"  forall k z x. foldr k z [x] = k x z
+"foldr/nil"     forall k z.   foldr k z []  = z 

 
 "augment/build" forall (g::forall b. (a->b->b) -> b -> b)
 
 "augment/build" forall (g::forall b. (a->b->b) -> b -> b)

-                      (h::forall b. (a->b->b) -> b -> b) .
-                      augment g (build h) = build (\c n -> g c (h c n))
+                       (h::forall b. (a->b->b) -> b -> b) .
+                       augment g (build h) = build (\c n -> g c (h c n))

 "augment/nil"   forall (g::forall b. (a->b->b) -> b -> b) .
 "augment/nil"   forall (g::forall b. (a->b->b) -> b -> b) .

-                       augment g [] = build g
+                        augment g [] = build g

  #-}
 
 -- This rule is true, but not (I think) useful:
  #-}
 
 -- This rule is true, but not (I think) useful:

---     augment g (augment h t) = augment (\cn -> g c (h c n)) t
+--      augment g (augment h t) = augment (\cn -> g c (h c n)) t

 \end{code}
 
 
 ----------------------------------------------
 \end{code}
 
 
 ----------------------------------------------

---             map     
+--              map     

 ----------------------------------------------
 
 \begin{code}
 ----------------------------------------------
 
 \begin{code}

@@ -429,15 +434,15 @@ mapFB c f x ys = c (f x) ys
 -- e.g. append, filter, iterate, repeat, etc.
 
 {-# RULES
 -- e.g. append, filter, iterate, repeat, etc.
 
 {-# RULES

-"map"      [~1] forall f xs.   map f xs                = build (\c n -> foldr (mapFB c f) n xs)
-"mapList"   [1]  forall f.     foldr (mapFB (:) f) []  = map f
-"mapFB"            forall c f g.       mapFB (mapFB c f) g     = mapFB c (f.g) 
+"map"       [~1] forall f xs.   map f xs                = build (\c n -> foldr (mapFB c f) n xs)
+"mapList"   [1]  forall f.      foldr (mapFB (:) f) []  = map f
+"mapFB"     forall c f g.       mapFB (mapFB c f) g     = mapFB c (f.g) 

   #-}
 \end{code}
 
 
 ----------------------------------------------
   #-}
 \end{code}
 
 
 ----------------------------------------------

---             append  
+--              append  

 ----------------------------------------------
 \begin{code}
 -- | Append two lists, i.e.,
 ----------------------------------------------
 \begin{code}
 -- | Append two lists, i.e.,

@@ -452,16 +457,16 @@ mapFB c f x ys = c (f x) ys
 (++) (x:xs) ys = x : xs ++ ys
 
 {-# RULES
 (++) (x:xs) ys = x : xs ++ ys
 
 {-# RULES

-"++"   [~1] forall xs ys. xs ++ ys = augment (\c n -> foldr c n xs) ys
+"++"    [~1] forall xs ys. xs ++ ys = augment (\c n -> foldr c n xs) ys

   #-}
 
 \end{code}
 
 
 %*********************************************************
   #-}
 
 \end{code}
 
 
 %*********************************************************

-%*                                                     *
+%*                                                      *

 \subsection{Type @Bool@}
 \subsection{Type @Bool@}

-%*                                                     *
+%*                                                      *

 %*********************************************************
 
 \begin{code}
 %*********************************************************
 
 \begin{code}

@@ -469,88 +474,86 @@ mapFB c f x ys = c (f x) ys
 -- first so that the corresponding 'Prelude.Enum' instance will give
 -- 'Prelude.fromEnum' 'False' the value zero, and
 -- 'Prelude.fromEnum' 'True' the value 1.
 -- first so that the corresponding 'Prelude.Enum' instance will give
 -- 'Prelude.fromEnum' 'False' the value zero, and
 -- 'Prelude.fromEnum' 'True' the value 1.

-data  Bool  =  False | True  deriving (Eq, Ord)
-       -- Read in GHC.Read, Show in GHC.Show
+-- The actual definition is in the ghc-prim package.
+
+-- XXX These don't work:
+-- deriving instance Eq Bool
+-- deriving instance Ord Bool
+-- <wired into compiler>:
+--     Illegal binding of built-in syntax: con2tag_Bool#
+
+instance Eq Bool where
+    True  == True  = True
+    False == False = True
+    _     == _     = False
+
+instance Ord Bool where
+    compare False True  = LT
+    compare True  False = GT
+    compare _     _     = EQ
+
+-- Read is in GHC.Read, Show in GHC.Show

 
 -- Boolean functions
 
 -- | Boolean \"and\"
 
 -- Boolean functions
 
 -- | Boolean \"and\"

-(&&)                   :: Bool -> Bool -> Bool
-True  && x             =  x
-False && _             =  False
+(&&)                    :: Bool -> Bool -> Bool
+True  && x              =  x
+False && _              =  False

 
 -- | Boolean \"or\"
 
 -- | Boolean \"or\"

-(||)                   :: Bool -> Bool -> Bool
-True  || _             =  True
-False || x             =  x
+(||)                    :: Bool -> Bool -> Bool
+True  || _              =  True
+False || x              =  x

 
 -- | Boolean \"not\"
 
 -- | Boolean \"not\"

-not                    :: Bool -> Bool
-not True               =  False
-not False              =  True
+not                     :: Bool -> Bool
+not True                =  False
+not False               =  True

 
 -- |'otherwise' is defined as the value 'True'.  It helps to make
 -- guards more readable.  eg.
 --
 -- >  f x | x < 0     = ...
 -- >      | otherwise = ...
 
 -- |'otherwise' is defined as the value 'True'.  It helps to make
 -- guards more readable.  eg.
 --
 -- >  f x | x < 0     = ...
 -- >      | otherwise = ...

-otherwise              :: Bool
-otherwise              =  True
+otherwise               :: Bool
+otherwise               =  True

 \end{code}
 
 \end{code}
 

-
-%*********************************************************
-%*                                                     *
-\subsection{The @()@ type}
-%*                                                     *

 %*********************************************************
 %*********************************************************

-
-The Unit type is here because virtually any program needs it (whereas
-some programs may get away without consulting GHC.Tup).  Furthermore,
-the renamer currently *always* asks for () to be in scope, so that
-ccalls can use () as their default type; so when compiling GHC.Base we
-need ().  (We could arrange suck in () only if -fglasgow-exts, but putting
-it here seems more direct.)
-
-\begin{code}
--- | The unit datatype @()@ has one non-undefined member, the nullary
--- constructor @()@.
-data () = ()
-
-instance Eq () where
-    () == () = True
-    () /= () = False
-
-instance Ord () where
-    () <= () = True
-    () <  () = False
-    () >= () = True
-    () >  () = False
-    max () () = ()
-    min () () = ()
-    compare () () = EQ
-\end{code}
-
-
-%*********************************************************
-%*                                                     *
+%*                                                      *

 \subsection{Type @Ordering@}
 \subsection{Type @Ordering@}

-%*                                                     *
+%*                                                      *

 %*********************************************************
 
 \begin{code}
 -- | Represents an ordering relationship between two values: less
 -- than, equal to, or greater than.  An 'Ordering' is returned by
 -- 'compare'.
 %*********************************************************
 
 \begin{code}
 -- | Represents an ordering relationship between two values: less
 -- than, equal to, or greater than.  An 'Ordering' is returned by
 -- 'compare'.

-data Ordering = LT | EQ | GT deriving (Eq, Ord)
-       -- Read in GHC.Read, Show in GHC.Show
+-- XXX These don't work:
+-- deriving instance Eq Ordering
+-- deriving instance Ord Ordering
+-- Illegal binding of built-in syntax: con2tag_Ordering#
+instance Eq Ordering where
+    EQ == EQ = True
+    LT == LT = True
+    GT == GT = True
+    _  == _  = False
+        -- Read in GHC.Read, Show in GHC.Show
+
+instance Ord Ordering where
+    LT <= _  = True
+    _  <= LT = False
+    EQ <= _  = True
+    _  <= EQ = False
+    GT <= GT = True

 \end{code}
 
 
 %*********************************************************
 \end{code}
 
 
 %*********************************************************

-%*                                                     *
+%*                                                      *

 \subsection{Type @Char@ and @String@}
 \subsection{Type @Char@ and @String@}

-%*                                                     *
+%*                                                      *

 %*********************************************************
 
 \begin{code}
 %*********************************************************
 
 \begin{code}

@@ -613,18 +616,20 @@ String equality is used when desugaring pattern-matches against strings.
 
 \begin{code}
 eqString :: String -> String -> Bool
 
 \begin{code}
 eqString :: String -> String -> Bool

-eqString []       []      = True
+eqString []       []       = True

 eqString (c1:cs1) (c2:cs2) = c1 == c2 && cs1 `eqString` cs2
 eqString (c1:cs1) (c2:cs2) = c1 == c2 && cs1 `eqString` cs2

-eqString cs1      cs2     = False
+eqString cs1      cs2      = False

 
 {-# RULES "eqString" (==) = eqString #-}
 
 {-# RULES "eqString" (==) = eqString #-}

+-- eqString also has a BuiltInRule in PrelRules.lhs:
+--      eqString (unpackCString# (Lit s1)) (unpackCString# (Lit s2) = s1==s2

 \end{code}
 
 
 %*********************************************************
 \end{code}
 
 
 %*********************************************************

-%*                                                     *
+%*                                                      *

 \subsection{Type @Int@}
 \subsection{Type @Int@}

-%*                                                     *
+%*                                                      *

 %*********************************************************
 
 \begin{code}
 %*********************************************************
 
 \begin{code}

@@ -673,23 +678,36 @@ compareInt# x# y#
 
 
 %*********************************************************
 
 
 %*********************************************************

-%*                                                     *
+%*                                                      *

 \subsection{The function type}
 \subsection{The function type}

-%*                                                     *
+%*                                                      *

 %*********************************************************
 
 \begin{code}
 -- | Identity function.
 %*********************************************************
 
 \begin{code}
 -- | Identity function.

-id                     :: a -> a
-id x                   =  x
+id                      :: a -> a
+id x                    =  x

 
 

--- lazy function; this is just the same as id, but its unfolding
--- and strictness are over-ridden by the definition in MkId.lhs
--- That way, it does not get inlined, and the strictness analyser
--- sees it as lazy.  Then the worker/wrapper phase inlines it.
--- Result: happiness
+-- | The call '(lazy e)' means the same as 'e', but 'lazy' has a 
+-- magical strictness property: it is lazy in its first argument, 
+-- even though its semantics is strict.

 lazy :: a -> a
 lazy x = x
 lazy :: a -> a
 lazy x = x

+-- Implementation note: its strictness and unfolding are over-ridden
+-- by the definition in MkId.lhs; in both cases to nothing at all.
+-- That way, 'lazy' does not get inlined, and the strictness analyser
+-- sees it as lazy.  Then the worker/wrapper phase inlines it.
+-- Result: happiness
+
+
+-- | The call '(inline f)' reduces to 'f', but 'inline' has a BuiltInRule
+-- that tries to inline 'f' (if it has an unfolding) unconditionally
+-- The 'NOINLINE' pragma arranges that inline only gets inlined (and
+-- hence eliminated) late in compilation, after the rule has had
+-- a god chance to fire.
+inline :: a -> a
+{-# NOINLINE[0] inline #-}
+inline x = x

 
 -- Assertion function.  This simply ignores its boolean argument.
 -- The compiler may rewrite it to @('assertError' line)@.
 
 -- Assertion function.  This simply ignores its boolean argument.
 -- The compiler may rewrite it to @('assertError' line)@.

@@ -700,29 +718,38 @@ lazy x = x
 -- call to 'assert'.
 --
 -- Assertions can normally be turned on or off with a compiler flag
 -- call to 'assert'.
 --
 -- Assertions can normally be turned on or off with a compiler flag

--- (for GHC, assertions are normally on unless the @-fignore-asserts@
+-- (for GHC, assertions are normally on unless optimisation is turned on 
+-- with @-O@ or the @-fignore-asserts@

 -- option is given).  When assertions are turned off, the first
 -- argument to 'assert' is ignored, and the second argument is
 -- returned as the result.
 
 -- option is given).  When assertions are turned off, the first
 -- argument to 'assert' is ignored, and the second argument is
 -- returned as the result.
 

---     SLPJ: in 5.04 etc 'assert' is in GHC.Prim,
---     but from Template Haskell onwards it's simply
---     defined here in Base.lhs
+--      SLPJ: in 5.04 etc 'assert' is in GHC.Prim,
+--      but from Template Haskell onwards it's simply
+--      defined here in Base.lhs

 assert :: Bool -> a -> a
 assert pred r = r
 assert :: Bool -> a -> a
 assert pred r = r

- 
+
+breakpoint :: a -> a
+breakpoint r = r
+
+breakpointCond :: Bool -> a -> a
+breakpointCond _ r = r
+
+data Opaque = forall a. O a
+

 -- | Constant function.
 -- | Constant function.

-const                  :: a -> b -> a
-const x _              =  x
+const                   :: a -> b -> a
+const x _               =  x

 
 -- | Function composition.
 {-# INLINE (.) #-}
 
 -- | Function composition.
 {-# INLINE (.) #-}

-(.)      :: (b -> c) -> (a -> b) -> a -> c
-(.) f g        x = f (g x)
+(.)       :: (b -> c) -> (a -> b) -> a -> c
+(.) f g x = f (g x)

 
 -- | @'flip' f@ takes its (first) two arguments in the reverse order of @f@.
 
 -- | @'flip' f@ takes its (first) two arguments in the reverse order of @f@.

-flip                   :: (a -> b -> c) -> b -> a -> c
-flip f x y             =  f y x
+flip                    :: (a -> b -> c) -> b -> a -> c
+flip f x y              =  f y x

 
 -- | Application operator.  This operator is redundant, since ordinary
 -- application @(f x)@ means the same as @(f '$' x)@. However, '$' has
 
 -- | Application operator.  This operator is redundant, since ordinary
 -- application @(f x)@ means the same as @(f '$' x)@. However, '$' has

@@ -734,39 +761,25 @@ flip f x y                =  f y x
 -- It is also useful in higher-order situations, such as @'map' ('$' 0) xs@,
 -- or @'Data.List.zipWith' ('$') fs xs@.
 {-# INLINE ($) #-}
 -- It is also useful in higher-order situations, such as @'map' ('$' 0) xs@,
 -- or @'Data.List.zipWith' ('$') fs xs@.
 {-# INLINE ($) #-}

-($)                    :: (a -> b) -> a -> b
-f $ x                  =  f x
+($)                     :: (a -> b) -> a -> b
+f $ x                   =  f x

 
 -- | @'until' p f@ yields the result of applying @f@ until @p@ holds.
 
 -- | @'until' p f@ yields the result of applying @f@ until @p@ holds.

-until                  :: (a -> Bool) -> (a -> a) -> a -> a
-until p f x | p x      =  x
-           | otherwise =  until p f (f x)
+until                   :: (a -> Bool) -> (a -> a) -> a -> a
+until p f x | p x       =  x
+            | otherwise =  until p f (f x)

 
 -- | 'asTypeOf' is a type-restricted version of 'const'.  It is usually
 -- used as an infix operator, and its typing forces its first argument
 -- (which is usually overloaded) to have the same type as the second.
 
 -- | 'asTypeOf' is a type-restricted version of 'const'.  It is usually
 -- used as an infix operator, and its typing forces its first argument
 -- (which is usually overloaded) to have the same type as the second.

-asTypeOf               :: a -> a -> a
-asTypeOf               =  const
+asTypeOf                :: a -> a -> a
+asTypeOf                =  const

 \end{code}
 
 %*********************************************************
 \end{code}
 
 %*********************************************************

-%*                                                     *
-\subsection{Generics}
-%*                                                     *
-%*********************************************************
-
-\begin{code}
-data Unit = Unit
-#ifndef __HADDOCK__
-data (:+:) a b = Inl a | Inr b
-data (:*:) a b = a :*: b
-#endif
-\end{code}
-
-%*********************************************************
-%*                                                     *
+%*                                                      *

 \subsection{@getTag@}
 \subsection{@getTag@}

-%*                                                     *
+%*                                                      *

 %*********************************************************
 
 Returns the 'tag' of a constructor application; this function is used
 %*********************************************************
 
 Returns the 'tag' of a constructor application; this function is used

@@ -788,17 +801,17 @@ getTag x = x `seq` dataToTag# x
 \end{code}
 
 %*********************************************************
 \end{code}
 
 %*********************************************************

-%*                                                     *
+%*                                                      *

 \subsection{Numeric primops}
 \subsection{Numeric primops}

-%*                                                     *
+%*                                                      *

 %*********************************************************
 
 \begin{code}
 divInt# :: Int# -> Int# -> Int#
 x# `divInt#` y#
 %*********************************************************
 
 \begin{code}
 divInt# :: Int# -> Int# -> Int#
 x# `divInt#` y#

-       -- Be careful NOT to overflow if we do any additional arithmetic
-       -- on the arguments...  the following  previous version of this
-       -- code has problems with overflow:
+        -- Be careful NOT to overflow if we do any additional arithmetic
+        -- on the arguments...  the following  previous version of this
+        -- code has problems with overflow:

 --    | (x# ># 0#) && (y# <# 0#) = ((x# -# y#) -# 1#) `quotInt#` y#
 --    | (x# <# 0#) && (y# ># 0#) = ((x# -# y#) +# 1#) `quotInt#` y#
     | (x# ># 0#) && (y# <# 0#) = ((x# -# 1#) `quotInt#` y#) -# 1#
 --    | (x# ># 0#) && (y# <# 0#) = ((x# -# y#) -# 1#) `quotInt#` y#
 --    | (x# <# 0#) && (y# ># 0#) = ((x# -# y#) +# 1#) `quotInt#` y#
     | (x# ># 0#) && (y# <# 0#) = ((x# -# 1#) `quotInt#` y#) -# 1#

@@ -898,14 +911,26 @@ gtInt, geInt, eqInt, neInt, ltInt, leInt :: Int -> Int -> Bool
 "plusDouble x 0.0"   forall x#. (+##) x#    0.0## = x#
 "plusDouble 0.0 x"   forall x#. (+##) 0.0## x#    = x#
 "minusDouble x 0.0"  forall x#. (-##) x#    0.0## = x#
 "plusDouble x 0.0"   forall x#. (+##) x#    0.0## = x#
 "plusDouble 0.0 x"   forall x#. (+##) 0.0## x#    = x#
 "minusDouble x 0.0"  forall x#. (-##) x#    0.0## = x#

-"minusDouble x x"    forall x#. (-##) x#    x#    = 0.0##
-"timesDouble x 0.0"  forall x#. (*##) x#    0.0## = 0.0##
-"timesDouble 0.0 x"  forall x#. (*##) 0.0## x#    = 0.0##

 "timesDouble x 1.0"  forall x#. (*##) x#    1.0## = x#
 "timesDouble 1.0 x"  forall x#. (*##) 1.0## x#    = x#
 "divideDouble x 1.0" forall x#. (/##) x#    1.0## = x#
   #-}
 
 "timesDouble x 1.0"  forall x#. (*##) x#    1.0## = x#
 "timesDouble 1.0 x"  forall x#. (*##) 1.0## x#    = x#
 "divideDouble x 1.0" forall x#. (/##) x#    1.0## = x#
   #-}
 

+{-
+We'd like to have more rules, but for example:
+
+This gives wrong answer (0) for NaN - NaN (should be NaN):
+    "minusDouble x x"    forall x#. (-##) x#    x#    = 0.0##
+
+This gives wrong answer (0) for 0 * NaN (should be NaN):
+    "timesDouble 0.0 x"  forall x#. (*##) 0.0## x#    = 0.0##
+
+This gives wrong answer (0) for NaN * 0 (should be NaN):
+    "timesDouble x 0.0"  forall x#. (*##) x#    0.0## = 0.0##
+
+These are tested by num014.
+-}
+

 -- Wrappers for the shift operations.  The uncheckedShift# family are
 -- undefined when the amount being shifted by is greater than the size
 -- in bits of Int#, so these wrappers perform a check and return
 -- Wrappers for the shift operations.  The uncheckedShift# family are
 -- undefined when the amount being shifted by is greater than the size
 -- in bits of Int#, so these wrappers perform a check and return

@@ -918,31 +943,31 @@ gtInt, geInt, eqInt, neInt, ltInt, leInt :: Int -> Int -> Bool
 -- (which must be non-negative).
 shiftL# :: Word# -> Int# -> Word#
 a `shiftL#` b   | b >=# WORD_SIZE_IN_BITS# = int2Word# 0#
 -- (which must be non-negative).
 shiftL# :: Word# -> Int# -> Word#
 a `shiftL#` b   | b >=# WORD_SIZE_IN_BITS# = int2Word# 0#

-               | otherwise                = a `uncheckedShiftL#` b
+                | otherwise                = a `uncheckedShiftL#` b

 
 -- | Shift the argument right by the specified number of bits
 -- (which must be non-negative).
 shiftRL# :: Word# -> Int# -> Word#
 a `shiftRL#` b  | b >=# WORD_SIZE_IN_BITS# = int2Word# 0#
 
 -- | Shift the argument right by the specified number of bits
 -- (which must be non-negative).
 shiftRL# :: Word# -> Int# -> Word#
 a `shiftRL#` b  | b >=# WORD_SIZE_IN_BITS# = int2Word# 0#

-               | otherwise                = a `uncheckedShiftRL#` b
+                | otherwise                = a `uncheckedShiftRL#` b

 
 -- | Shift the argument left by the specified number of bits
 -- (which must be non-negative).
 iShiftL# :: Int# -> Int# -> Int#
 a `iShiftL#` b  | b >=# WORD_SIZE_IN_BITS# = 0#
 
 -- | Shift the argument left by the specified number of bits
 -- (which must be non-negative).
 iShiftL# :: Int# -> Int# -> Int#
 a `iShiftL#` b  | b >=# WORD_SIZE_IN_BITS# = 0#

-               | otherwise                = a `uncheckedIShiftL#` b
+                | otherwise                = a `uncheckedIShiftL#` b

 
 -- | Shift the argument right (signed) by the specified number of bits
 -- (which must be non-negative).
 iShiftRA# :: Int# -> Int# -> Int#
 a `iShiftRA#` b | b >=# WORD_SIZE_IN_BITS# = if a <# 0# then (-1#) else 0#
 
 -- | Shift the argument right (signed) by the specified number of bits
 -- (which must be non-negative).
 iShiftRA# :: Int# -> Int# -> Int#
 a `iShiftRA#` b | b >=# WORD_SIZE_IN_BITS# = if a <# 0# then (-1#) else 0#

-               | otherwise                = a `uncheckedIShiftRA#` b
+                | otherwise                = a `uncheckedIShiftRA#` b

 
 -- | Shift the argument right (unsigned) by the specified number of bits
 -- (which must be non-negative).
 iShiftRL# :: Int# -> Int# -> Int#
 a `iShiftRL#` b | b >=# WORD_SIZE_IN_BITS# = 0#
 
 -- | Shift the argument right (unsigned) by the specified number of bits
 -- (which must be non-negative).
 iShiftRL# :: Int# -> Int# -> Int#
 a `iShiftRL#` b | b >=# WORD_SIZE_IN_BITS# = 0#

-               | otherwise                = a `uncheckedIShiftRL#` b
+                | otherwise                = a `uncheckedIShiftRL#` b

 
 #if WORD_SIZE_IN_BITS == 32
 {-# RULES
 
 #if WORD_SIZE_IN_BITS == 32
 {-# RULES

@@ -959,9 +984,9 @@ a `iShiftRL#` b | b >=# WORD_SIZE_IN_BITS# = 0#
 
 
 %********************************************************
 
 
 %********************************************************

-%*                                                     *
+%*                                                      *

 \subsection{Unpacking C strings}
 \subsection{Unpacking C strings}

-%*                                                     *
+%*                                                      *

 %********************************************************
 
 This code is needed for virtually all programs, since it's used for
 %********************************************************
 
 This code is needed for virtually all programs, since it's used for

@@ -975,9 +1000,9 @@ unpackCString# addr
   where
     unpack nh
       | ch `eqChar#` '\0'# = []
   where
     unpack nh
       | ch `eqChar#` '\0'# = []

-      | otherwise         = C# ch : unpack (nh +# 1#)
+      | otherwise          = C# ch : unpack (nh +# 1#)

       where
       where

-       ch = indexCharOffAddr# addr nh
+        ch = indexCharOffAddr# addr nh

 
 unpackAppendCString# :: Addr# -> [Char] -> [Char]
 unpackAppendCString# addr rest
 
 unpackAppendCString# :: Addr# -> [Char] -> [Char]
 unpackAppendCString# addr rest

@@ -985,22 +1010,25 @@ unpackAppendCString# addr rest
   where
     unpack nh
       | ch `eqChar#` '\0'# = rest
   where
     unpack nh
       | ch `eqChar#` '\0'# = rest

-      | otherwise         = C# ch : unpack (nh +# 1#)
+      | otherwise          = C# ch : unpack (nh +# 1#)

       where
       where

-       ch = indexCharOffAddr# addr nh
+        ch = indexCharOffAddr# addr nh

 
 unpackFoldrCString# :: Addr# -> (Char  -> a -> a) -> a -> a 
 {-# NOINLINE [0] unpackFoldrCString# #-}
 -- Don't inline till right at the end;
 -- usually the unpack-list rule turns it into unpackCStringList
 
 unpackFoldrCString# :: Addr# -> (Char  -> a -> a) -> a -> a 
 {-# NOINLINE [0] unpackFoldrCString# #-}
 -- Don't inline till right at the end;
 -- usually the unpack-list rule turns it into unpackCStringList

+-- It also has a BuiltInRule in PrelRules.lhs:
+--      unpackFoldrCString# "foo" c (unpackFoldrCString# "baz" c n)
+--        =  unpackFoldrCString# "foobaz" c n

 unpackFoldrCString# addr f z 
   = unpack 0#
   where
     unpack nh
       | ch `eqChar#` '\0'# = z
 unpackFoldrCString# addr f z 
   = unpack 0#
   where
     unpack nh
       | ch `eqChar#` '\0'# = z

-      | otherwise         = C# ch `f` unpack (nh +# 1#)
+      | otherwise          = C# ch `f` unpack (nh +# 1#)

       where
       where

-       ch = indexCharOffAddr# addr nh
+        ch = indexCharOffAddr# addr nh

 
 unpackCStringUtf8# :: Addr# -> [Char]
 unpackCStringUtf8# addr 
 
 unpackCStringUtf8# :: Addr# -> [Char]
 unpackCStringUtf8# addr 

@@ -1025,7 +1053,7 @@ unpackCStringUtf8# addr
                      (ord# (indexCharOffAddr# addr (nh +# 3#)) -# 0x80#))) :
           unpack (nh +# 4#)
       where
                      (ord# (indexCharOffAddr# addr (nh +# 3#)) -# 0x80#))) :
           unpack (nh +# 4#)
       where

-       ch = indexCharOffAddr# addr nh
+        ch = indexCharOffAddr# addr nh

 
 unpackNBytes# :: Addr# -> Int# -> [Char]
 unpackNBytes# _addr 0#   = []
 
 unpackNBytes# :: Addr# -> Int# -> [Char]
 unpackNBytes# _addr 0#   = []

@@ -1034,16 +1062,16 @@ unpackNBytes#  addr len# = unpack [] (len# -# 1#)
      unpack acc i#
       | i# <# 0#  = acc
       | otherwise = 
      unpack acc i#
       | i# <# 0#  = acc
       | otherwise = 

-        case indexCharOffAddr# addr i# of
-           ch -> unpack (C# ch : acc) (i# -# 1#)
+         case indexCharOffAddr# addr i# of
+            ch -> unpack (C# ch : acc) (i# -# 1#)

 
 {-# RULES
 
 {-# RULES

-"unpack"       [~1] forall a   . unpackCString# a                 = build (unpackFoldrCString# a)
+"unpack"       [~1] forall a   . unpackCString# a                  = build (unpackFoldrCString# a)

 "unpack-list"  [1]  forall a   . unpackFoldrCString# a (:) [] = unpackCString# a
 "unpack-append"     forall a n . unpackFoldrCString# a (:) n  = unpackAppendCString# a n
 
 -- There's a built-in rule (in PrelRules.lhs) for
 "unpack-list"  [1]  forall a   . unpackFoldrCString# a (:) [] = unpackCString# a
 "unpack-append"     forall a n . unpackFoldrCString# a (:) n  = unpackAppendCString# a n
 
 -- There's a built-in rule (in PrelRules.lhs) for

---     unpackFoldr "foo" c (unpackFoldr "baz" c n)  =  unpackFoldr "foobaz" c n
+--      unpackFoldr "foo" c (unpackFoldr "baz" c n)  =  unpackFoldr "foobaz" c n

 
   #-}
 \end{code}
 
   #-}
 \end{code}