1 \section[GHC.Base]{Module @GHC.Base@}
3 The overall structure of the GHC Prelude is a bit tricky.
5 a) We want to avoid "orphan modules", i.e. ones with instance
6 decls that don't belong either to a tycon or a class
7 defined in the same module
9 b) We want to avoid giant modules
11 So the rough structure is as follows, in (linearised) dependency order
14 GHC.Prim Has no implementation. It defines built-in things, and
15 by importing it you bring them into scope.
16 The source file is GHC.Prim.hi-boot, which is just
17 copied to make GHC.Prim.hi
19 GHC.Base Classes: Eq, Ord, Functor, Monad
20 Types: list, (), Int, Bool, Ordering, Char, String
22 Data.Tup Types: tuples, plus instances for GHC.Base classes
24 GHC.Show Class: Show, plus instances for GHC.Base/GHC.Tup types
26 GHC.Enum Class: Enum, plus instances for GHC.Base/GHC.Tup types
28 Data.Maybe Type: Maybe, plus instances for GHC.Base classes
30 GHC.Num Class: Num, plus instances for Int
31 Type: Integer, plus instances for all classes so far (Eq, Ord, Num, Show)
33 Integer is needed here because it is mentioned in the signature
34 of 'fromInteger' in class Num
36 GHC.Real Classes: Real, Integral, Fractional, RealFrac
37 plus instances for Int, Integer
38 Types: Ratio, Rational
39 plus intances for classes so far
41 Rational is needed here because it is mentioned in the signature
42 of 'toRational' in class Real
44 Ix Classes: Ix, plus instances for Int, Bool, Char, Integer, Ordering, tuples
46 GHC.Arr Types: Array, MutableArray, MutableVar
48 Does *not* contain any ByteArray stuff (see GHC.ByteArr)
49 Arrays are used by a function in GHC.Float
51 GHC.Float Classes: Floating, RealFloat
52 Types: Float, Double, plus instances of all classes so far
54 This module contains everything to do with floating point.
55 It is a big module (900 lines)
56 With a bit of luck, many modules can be compiled without ever reading GHC.Float.hi
58 GHC.ByteArr Types: ByteArray, MutableByteArray
60 We want this one to be after GHC.Float, because it defines arrays
64 Other Prelude modules are much easier with fewer complex dependencies.
67 {-# OPTIONS_GHC -fno-implicit-prelude #-}
68 -----------------------------------------------------------------------------
71 -- Copyright : (c) The University of Glasgow, 1992-2002
72 -- License : see libraries/base/LICENSE
74 -- Maintainer : cvs-ghc@haskell.org
75 -- Stability : internal
76 -- Portability : non-portable (GHC extensions)
78 -- Basic data types and classes.
80 -----------------------------------------------------------------------------
87 module GHC.Prim, -- Re-export GHC.Prim and GHC.Err, to avoid lots
88 module GHC.Err -- of people having to import it explicitly
93 import {-# SOURCE #-} GHC.Err
97 infix 4 ==, /=, <, <=, >=, >
103 default () -- Double isn't available yet
107 %*********************************************************
109 \subsection{DEBUGGING STUFF}
110 %* (for use when compiling GHC.Base itself doesn't work)
112 %*********************************************************
116 data Bool = False | True
117 data Ordering = LT | EQ | GT
125 (&&) True True = True
131 unpackCString# :: Addr# -> [Char]
132 unpackFoldrCString# :: Addr# -> (Char -> a -> a) -> a -> a
133 unpackAppendCString# :: Addr# -> [Char] -> [Char]
134 unpackCStringUtf8# :: Addr# -> [Char]
135 unpackCString# a = error "urk"
136 unpackFoldrCString# a = error "urk"
137 unpackAppendCString# a = error "urk"
138 unpackCStringUtf8# a = error "urk"
143 %*********************************************************
145 \subsection{Standard classes @Eq@, @Ord@}
147 %*********************************************************
151 -- | The 'Eq' class defines equality ('==') and inequality ('/=').
152 -- All the basic datatypes exported by the "Prelude" are instances of 'Eq',
153 -- and 'Eq' may be derived for any datatype whose constituents are also
154 -- instances of 'Eq'.
156 -- Minimal complete definition: either '==' or '/='.
159 (==), (/=) :: a -> a -> Bool
161 x /= y = not (x == y)
162 x == y = not (x /= y)
164 -- | The 'Ord' class is used for totally ordered datatypes.
166 -- Instances of 'Ord' can be derived for any user-defined
167 -- datatype whose constituent types are in 'Ord'. The declared order
168 -- of the constructors in the data declaration determines the ordering
169 -- in derived 'Ord' instances. The 'Ordering' datatype allows a single
170 -- comparison to determine the precise ordering of two objects.
172 -- Minimal complete definition: either 'compare' or '<='.
173 -- Using 'compare' can be more efficient for complex types.
175 class (Eq a) => Ord a where
176 compare :: a -> a -> Ordering
177 (<), (<=), (>), (>=) :: a -> a -> Bool
178 max, min :: a -> a -> a
182 | x <= y = LT -- NB: must be '<=' not '<' to validate the
183 -- above claim about the minimal things that
184 -- can be defined for an instance of Ord
187 x < y = case compare x y of { LT -> True; _other -> False }
188 x <= y = case compare x y of { GT -> False; _other -> True }
189 x > y = case compare x y of { GT -> True; _other -> False }
190 x >= y = case compare x y of { LT -> False; _other -> True }
192 -- These two default methods use '<=' rather than 'compare'
193 -- because the latter is often more expensive
194 max x y = if x <= y then y else x
195 min x y = if x <= y then x else y
198 %*********************************************************
200 \subsection{Monadic classes @Functor@, @Monad@ }
202 %*********************************************************
205 {- | The 'Functor' class is used for types that can be mapped over.
206 Instances of 'Functor' should satisfy the following laws:
209 > fmap (f . g) == fmap f . fmap g
211 The instances of 'Functor' for lists, 'Maybe' and 'IO' defined in the "Prelude"
215 class Functor f where
216 fmap :: (a -> b) -> f a -> f b
218 {- | The 'Monad' class defines the basic operations over a /monad/.
219 Instances of 'Monad' should satisfy the following laws:
221 > return a >>= k == k a
223 > m >>= (\x -> k x >>= h) == (m >>= k) >>= h
225 Instances of both 'Monad' and 'Functor' should additionally satisfy the law:
227 > fmap f xs == xs >>= return . f
229 The instances of 'Monad' for lists, 'Maybe' and 'IO' defined in the "Prelude"
234 (>>=) :: forall a b. m a -> (a -> m b) -> m b
235 (>>) :: forall a b. m a -> m b -> m b
236 -- Explicit for-alls so that we know what order to
237 -- give type arguments when desugaring
239 fail :: String -> m a
241 m >> k = m >>= \_ -> k
246 %*********************************************************
248 \subsection{The list type}
250 %*********************************************************
253 data [] a = [] | a : [a] -- do explicitly: deriving (Eq, Ord)
254 -- to avoid weird names like con2tag_[]#
257 instance (Eq a) => Eq [a] where
258 {-# SPECIALISE instance Eq [Char] #-}
260 (x:xs) == (y:ys) = x == y && xs == ys
263 instance (Ord a) => Ord [a] where
264 {-# SPECIALISE instance Ord [Char] #-}
266 compare [] (_:_) = LT
267 compare (_:_) [] = GT
268 compare (x:xs) (y:ys) = case compare x y of
272 instance Functor [] where
275 instance Monad [] where
276 m >>= k = foldr ((++) . k) [] m
277 m >> k = foldr ((++) . (\ _ -> k)) [] m
282 A few list functions that appear here because they are used here.
283 The rest of the prelude list functions are in GHC.List.
285 ----------------------------------------------
286 -- foldr/build/augment
287 ----------------------------------------------
290 -- | 'foldr', applied to a binary operator, a starting value (typically
291 -- the right-identity of the operator), and a list, reduces the list
292 -- using the binary operator, from right to left:
294 -- > foldr f z [x1, x2, ..., xn] == x1 `f` (x2 `f` ... (xn `f` z)...)
296 foldr :: (a -> b -> b) -> b -> [a] -> b
298 -- foldr f z (x:xs) = f x (foldr f z xs)
299 {-# INLINE [0] foldr #-}
300 -- Inline only in the final stage, after the foldr/cons rule has had a chance
304 go (y:ys) = y `k` go ys
306 -- | A list producer that can be fused with 'foldr'.
307 -- This function is merely
309 -- > build g = g (:) []
311 -- but GHC's simplifier will transform an expression of the form
312 -- @'foldr' k z ('build' g)@, which may arise after inlining, to @g k z@,
313 -- which avoids producing an intermediate list.
315 build :: forall a. (forall b. (a -> b -> b) -> b -> b) -> [a]
316 {-# INLINE [1] build #-}
317 -- The INLINE is important, even though build is tiny,
318 -- because it prevents [] getting inlined in the version that
319 -- appears in the interface file. If [] *is* inlined, it
320 -- won't match with [] appearing in rules in an importing module.
322 -- The "1" says to inline in phase 1
326 -- | A list producer that can be fused with 'foldr'.
327 -- This function is merely
329 -- > augment g xs = g (:) xs
331 -- but GHC's simplifier will transform an expression of the form
332 -- @'foldr' k z ('augment' g xs)@, which may arise after inlining, to
333 -- @g k ('foldr' k z xs)@, which avoids producing an intermediate list.
335 augment :: forall a. (forall b. (a->b->b) -> b -> b) -> [a] -> [a]
336 {-# INLINE [1] augment #-}
337 augment g xs = g (:) xs
340 "fold/build" forall k z (g::forall b. (a->b->b) -> b -> b) .
341 foldr k z (build g) = g k z
343 "foldr/augment" forall k z xs (g::forall b. (a->b->b) -> b -> b) .
344 foldr k z (augment g xs) = g k (foldr k z xs)
346 "foldr/id" foldr (:) [] = \x->x
347 "foldr/app" [1] forall xs ys. foldr (:) ys xs = xs ++ ys
348 -- Only activate this from phase 1, because that's
349 -- when we disable the rule that expands (++) into foldr
351 -- The foldr/cons rule looks nice, but it can give disastrously
352 -- bloated code when commpiling
353 -- array (a,b) [(1,2), (2,2), (3,2), ...very long list... ]
354 -- i.e. when there are very very long literal lists
355 -- So I've disabled it for now. We could have special cases
356 -- for short lists, I suppose.
357 -- "foldr/cons" forall k z x xs. foldr k z (x:xs) = k x (foldr k z xs)
359 "foldr/single" forall k z x. foldr k z [x] = k x z
360 "foldr/nil" forall k z. foldr k z [] = z
362 "augment/build" forall (g::forall b. (a->b->b) -> b -> b)
363 (h::forall b. (a->b->b) -> b -> b) .
364 augment g (build h) = build (\c n -> g c (h c n))
365 "augment/nil" forall (g::forall b. (a->b->b) -> b -> b) .
366 augment g [] = build g
369 -- This rule is true, but not (I think) useful:
370 -- augment g (augment h t) = augment (\cn -> g c (h c n)) t
374 ----------------------------------------------
376 ----------------------------------------------
379 -- | 'map' @f xs@ is the list obtained by applying @f@ to each element
382 -- > map f [x1, x2, ..., xn] == [f x1, f x2, ..., f xn]
383 -- > map f [x1, x2, ...] == [f x1, f x2, ...]
385 map :: (a -> b) -> [a] -> [b]
387 map f (x:xs) = f x : map f xs
390 mapFB :: (elt -> lst -> lst) -> (a -> elt) -> a -> lst -> lst
391 {-# INLINE [0] mapFB #-}
392 mapFB c f x ys = c (f x) ys
394 -- The rules for map work like this.
396 -- Up to (but not including) phase 1, we use the "map" rule to
397 -- rewrite all saturated applications of map with its build/fold
398 -- form, hoping for fusion to happen.
399 -- In phase 1 and 0, we switch off that rule, inline build, and
400 -- switch on the "mapList" rule, which rewrites the foldr/mapFB
401 -- thing back into plain map.
403 -- It's important that these two rules aren't both active at once
404 -- (along with build's unfolding) else we'd get an infinite loop
405 -- in the rules. Hence the activation control below.
407 -- The "mapFB" rule optimises compositions of map.
409 -- This same pattern is followed by many other functions:
410 -- e.g. append, filter, iterate, repeat, etc.
413 "map" [~1] forall f xs. map f xs = build (\c n -> foldr (mapFB c f) n xs)
414 "mapList" [1] forall f. foldr (mapFB (:) f) [] = map f
415 "mapFB" forall c f g. mapFB (mapFB c f) g = mapFB c (f.g)
420 ----------------------------------------------
422 ----------------------------------------------
424 -- | Append two lists, i.e.,
426 -- > [x1, ..., xm] ++ [y1, ..., yn] == [x1, ..., xm, y1, ..., yn]
427 -- > [x1, ..., xm] ++ [y1, ...] == [x1, ..., xm, y1, ...]
429 -- If the first list is not finite, the result is the first list.
431 (++) :: [a] -> [a] -> [a]
433 (++) (x:xs) ys = x : xs ++ ys
436 "++" [~1] forall xs ys. xs ++ ys = augment (\c n -> foldr c n xs) ys
442 %*********************************************************
444 \subsection{Type @Bool@}
446 %*********************************************************
449 -- |The 'Bool' type is an enumeration. It is defined with 'False'
450 -- first so that the corresponding 'Prelude.Enum' instance will give
451 -- 'Prelude.fromEnum' 'False' the value zero, and
452 -- 'Prelude.fromEnum' 'True' the value 1.
453 data Bool = False | True deriving (Eq, Ord)
454 -- Read in GHC.Read, Show in GHC.Show
459 (&&) :: Bool -> Bool -> Bool
464 (||) :: Bool -> Bool -> Bool
473 -- |'otherwise' is defined as the value 'True'. It helps to make
474 -- guards more readable. eg.
476 -- > f x | x < 0 = ...
477 -- > | otherwise = ...
483 %*********************************************************
485 \subsection{The @()@ type}
487 %*********************************************************
489 The Unit type is here because virtually any program needs it (whereas
490 some programs may get away without consulting GHC.Tup). Furthermore,
491 the renamer currently *always* asks for () to be in scope, so that
492 ccalls can use () as their default type; so when compiling GHC.Base we
493 need (). (We could arrange suck in () only if -fglasgow-exts, but putting
494 it here seems more direct.)
497 -- | The unit datatype @()@ has one non-undefined member, the nullary
505 instance Ord () where
516 %*********************************************************
518 \subsection{Type @Ordering@}
520 %*********************************************************
523 -- | Represents an ordering relationship between two values: less
524 -- than, equal to, or greater than. An 'Ordering' is returned by
526 data Ordering = LT | EQ | GT deriving (Eq, Ord)
527 -- Read in GHC.Read, Show in GHC.Show
531 %*********************************************************
533 \subsection{Type @Char@ and @String@}
535 %*********************************************************
538 -- | A 'String' is a list of characters. String constants in Haskell are values
543 {-| The character type 'Char' is an enumeration whose values represent
544 Unicode (or equivalently ISO 10646) characters.
545 This set extends the ISO 8859-1 (Latin-1) character set
546 (the first 256 charachers), which is itself an extension of the ASCII
547 character set (the first 128 characters).
548 A character literal in Haskell has type 'Char'.
550 To convert a 'Char' to or from the corresponding 'Int' value defined
551 by Unicode, use 'Prelude.toEnum' and 'Prelude.fromEnum' from the
552 'Prelude.Enum' class respectively (or equivalently 'ord' and 'chr').
556 -- We don't use deriving for Eq and Ord, because for Ord the derived
557 -- instance defines only compare, which takes two primops. Then
558 -- '>' uses compare, and therefore takes two primops instead of one.
560 instance Eq Char where
561 (C# c1) == (C# c2) = c1 `eqChar#` c2
562 (C# c1) /= (C# c2) = c1 `neChar#` c2
564 instance Ord Char where
565 (C# c1) > (C# c2) = c1 `gtChar#` c2
566 (C# c1) >= (C# c2) = c1 `geChar#` c2
567 (C# c1) <= (C# c2) = c1 `leChar#` c2
568 (C# c1) < (C# c2) = c1 `ltChar#` c2
571 "x# `eqChar#` x#" forall x#. x# `eqChar#` x# = True
572 "x# `neChar#` x#" forall x#. x# `neChar#` x# = False
573 "x# `gtChar#` x#" forall x#. x# `gtChar#` x# = False
574 "x# `geChar#` x#" forall x#. x# `geChar#` x# = True
575 "x# `leChar#` x#" forall x#. x# `leChar#` x# = True
576 "x# `ltChar#` x#" forall x#. x# `ltChar#` x# = False
579 -- | The 'Prelude.toEnum' method restricted to the type 'Data.Char.Char'.
581 chr (I# i#) | int2Word# i# `leWord#` int2Word# 0x10FFFF# = C# (chr# i#)
582 | otherwise = error "Prelude.chr: bad argument"
584 unsafeChr :: Int -> Char
585 unsafeChr (I# i#) = C# (chr# i#)
587 -- | The 'Prelude.fromEnum' method restricted to the type 'Data.Char.Char'.
589 ord (C# c#) = I# (ord# c#)
592 String equality is used when desugaring pattern-matches against strings.
595 eqString :: String -> String -> Bool
596 eqString [] [] = True
597 eqString (c1:cs1) (c2:cs2) = c1 == c2 && cs1 `eqString` cs2
598 eqString cs1 cs2 = False
600 {-# RULES "eqString" (==) = eqString #-}
604 %*********************************************************
606 \subsection{Type @Int@}
608 %*********************************************************
612 -- ^A fixed-precision integer type with at least the range @[-2^29 .. 2^29-1]@.
613 -- The exact range for a given implementation can be determined by using
614 -- 'Prelude.minBound' and 'Prelude.maxBound' from the 'Prelude.Bounded' class.
616 zeroInt, oneInt, twoInt, maxInt, minInt :: Int
621 {- Seems clumsy. Should perhaps put minInt and MaxInt directly into MachDeps.h -}
622 #if WORD_SIZE_IN_BITS == 31
623 minInt = I# (-0x40000000#)
624 maxInt = I# 0x3FFFFFFF#
625 #elif WORD_SIZE_IN_BITS == 32
626 minInt = I# (-0x80000000#)
627 maxInt = I# 0x7FFFFFFF#
629 minInt = I# (-0x8000000000000000#)
630 maxInt = I# 0x7FFFFFFFFFFFFFFF#
633 instance Eq Int where
637 instance Ord Int where
644 compareInt :: Int -> Int -> Ordering
645 (I# x#) `compareInt` (I# y#) = compareInt# x# y#
647 compareInt# :: Int# -> Int# -> Ordering
655 %*********************************************************
657 \subsection{The function type}
659 %*********************************************************
662 -- | Identity function.
666 -- lazy function; this is just the same as id, but its unfolding
667 -- and strictness are over-ridden by the definition in MkId.lhs
668 -- That way, it does not get inlined, and the strictness analyser
669 -- sees it as lazy. Then the worker/wrapper phase inlines it.
674 -- | Assertion function. This simply ignores its boolean argument.
675 -- The compiler may rewrite it to @('assertError' line)@.
677 -- SLPJ: in 5.04 etc 'assert' is in GHC.Prim,
678 -- but from Template Haskell onwards it's simply
679 -- defined here in Base.lhs
680 assert :: Bool -> a -> a
683 -- | Constant function.
687 -- | Function composition.
689 (.) :: (b -> c) -> (a -> b) -> a -> c
692 -- | @'flip' f@ takes its (first) two arguments in the reverse order of @f@.
693 flip :: (a -> b -> c) -> b -> a -> c
696 -- | Application operator. This operator is redundant, since ordinary
697 -- application @(f x)@ means the same as @(f '$' x)@. However, '$' has
698 -- low, right-associative binding precedence, so it sometimes allows
699 -- parentheses to be omitted; for example:
701 -- > f $ g $ h x = f (g (h x))
703 -- It is also useful in higher-order situations, such as @'map' ('$' 0) xs@,
704 -- or @'Data.List.zipWith' ('$') fs xs@.
706 ($) :: (a -> b) -> a -> b
709 -- | @'until' p f@ yields the result of applying @f@ until @p@ holds.
710 until :: (a -> Bool) -> (a -> a) -> a -> a
711 until p f x | p x = x
712 | otherwise = until p f (f x)
714 -- | 'asTypeOf' is a type-restricted version of 'const'. It is usually
715 -- used as an infix operator, and its typing forces its first argument
716 -- (which is usually overloaded) to have the same type as the second.
717 asTypeOf :: a -> a -> a
721 %*********************************************************
723 \subsection{Generics}
725 %*********************************************************
730 data (:+:) a b = Inl a | Inr b
731 data (:*:) a b = a :*: b
735 %*********************************************************
737 \subsection{@getTag@}
739 %*********************************************************
741 Returns the 'tag' of a constructor application; this function is used
742 by the deriving code for Eq, Ord and Enum.
744 The primitive dataToTag# requires an evaluated constructor application
745 as its argument, so we provide getTag as a wrapper that performs the
746 evaluation before calling dataToTag#. We could have dataToTag#
747 evaluate its argument, but we prefer to do it this way because (a)
748 dataToTag# can be an inline primop if it doesn't need to do any
749 evaluation, and (b) we want to expose the evaluation to the
750 simplifier, because it might be possible to eliminate the evaluation
751 in the case when the argument is already known to be evaluated.
754 {-# INLINE getTag #-}
756 getTag x = x `seq` dataToTag# x
759 %*********************************************************
761 \subsection{Numeric primops}
763 %*********************************************************
766 divInt# :: Int# -> Int# -> Int#
768 -- Be careful NOT to overflow if we do any additional arithmetic
769 -- on the arguments... the following previous version of this
770 -- code has problems with overflow:
771 -- | (x# ># 0#) && (y# <# 0#) = ((x# -# y#) -# 1#) `quotInt#` y#
772 -- | (x# <# 0#) && (y# ># 0#) = ((x# -# y#) +# 1#) `quotInt#` y#
773 | (x# ># 0#) && (y# <# 0#) = ((x# -# 1#) `quotInt#` y#) -# 1#
774 | (x# <# 0#) && (y# ># 0#) = ((x# +# 1#) `quotInt#` y#) -# 1#
775 | otherwise = x# `quotInt#` y#
777 modInt# :: Int# -> Int# -> Int#
779 | (x# ># 0#) && (y# <# 0#) ||
780 (x# <# 0#) && (y# ># 0#) = if r# /=# 0# then r# +# y# else 0#
786 Definitions of the boxed PrimOps; these will be
787 used in the case of partial applications, etc.
796 {-# INLINE plusInt #-}
797 {-# INLINE minusInt #-}
798 {-# INLINE timesInt #-}
799 {-# INLINE quotInt #-}
800 {-# INLINE remInt #-}
801 {-# INLINE negateInt #-}
803 plusInt, minusInt, timesInt, quotInt, remInt, divInt, modInt, gcdInt :: Int -> Int -> Int
804 (I# x) `plusInt` (I# y) = I# (x +# y)
805 (I# x) `minusInt` (I# y) = I# (x -# y)
806 (I# x) `timesInt` (I# y) = I# (x *# y)
807 (I# x) `quotInt` (I# y) = I# (x `quotInt#` y)
808 (I# x) `remInt` (I# y) = I# (x `remInt#` y)
809 (I# x) `divInt` (I# y) = I# (x `divInt#` y)
810 (I# x) `modInt` (I# y) = I# (x `modInt#` y)
813 "x# +# 0#" forall x#. x# +# 0# = x#
814 "0# +# x#" forall x#. 0# +# x# = x#
815 "x# -# 0#" forall x#. x# -# 0# = x#
816 "x# -# x#" forall x#. x# -# x# = 0#
817 "x# *# 0#" forall x#. x# *# 0# = 0#
818 "0# *# x#" forall x#. 0# *# x# = 0#
819 "x# *# 1#" forall x#. x# *# 1# = x#
820 "1# *# x#" forall x#. 1# *# x# = x#
823 gcdInt (I# a) (I# b) = g a b
824 where g 0# 0# = error "GHC.Base.gcdInt: gcd 0 0 is undefined"
827 g _ _ = I# (gcdInt# absA absB)
829 absInt x = if x <# 0# then negateInt# x else x
834 negateInt :: Int -> Int
835 negateInt (I# x) = I# (negateInt# x)
837 gtInt, geInt, eqInt, neInt, ltInt, leInt :: Int -> Int -> Bool
838 (I# x) `gtInt` (I# y) = x ># y
839 (I# x) `geInt` (I# y) = x >=# y
840 (I# x) `eqInt` (I# y) = x ==# y
841 (I# x) `neInt` (I# y) = x /=# y
842 (I# x) `ltInt` (I# y) = x <# y
843 (I# x) `leInt` (I# y) = x <=# y
846 "x# ># x#" forall x#. x# ># x# = False
847 "x# >=# x#" forall x#. x# >=# x# = True
848 "x# ==# x#" forall x#. x# ==# x# = True
849 "x# /=# x#" forall x#. x# /=# x# = False
850 "x# <# x#" forall x#. x# <# x# = False
851 "x# <=# x#" forall x#. x# <=# x# = True
855 "plusFloat x 0.0" forall x#. plusFloat# x# 0.0# = x#
856 "plusFloat 0.0 x" forall x#. plusFloat# 0.0# x# = x#
857 "minusFloat x 0.0" forall x#. minusFloat# x# 0.0# = x#
858 "minusFloat x x" forall x#. minusFloat# x# x# = 0.0#
859 "timesFloat x 0.0" forall x#. timesFloat# x# 0.0# = 0.0#
860 "timesFloat0.0 x" forall x#. timesFloat# 0.0# x# = 0.0#
861 "timesFloat x 1.0" forall x#. timesFloat# x# 1.0# = x#
862 "timesFloat 1.0 x" forall x#. timesFloat# 1.0# x# = x#
863 "divideFloat x 1.0" forall x#. divideFloat# x# 1.0# = x#
867 "plusDouble x 0.0" forall x#. (+##) x# 0.0## = x#
868 "plusDouble 0.0 x" forall x#. (+##) 0.0## x# = x#
869 "minusDouble x 0.0" forall x#. (-##) x# 0.0## = x#
870 "minusDouble x x" forall x#. (-##) x# x# = 0.0##
871 "timesDouble x 0.0" forall x#. (*##) x# 0.0## = 0.0##
872 "timesDouble 0.0 x" forall x#. (*##) 0.0## x# = 0.0##
873 "timesDouble x 1.0" forall x#. (*##) x# 1.0## = x#
874 "timesDouble 1.0 x" forall x#. (*##) 1.0## x# = x#
875 "divideDouble x 1.0" forall x#. (/##) x# 1.0## = x#
878 -- Wrappers for the shift operations. The uncheckedShift# family are
879 -- undefined when the amount being shifted by is greater than the size
880 -- in bits of Int#, so these wrappers perform a check and return
881 -- either zero or -1 appropriately.
883 -- Note that these wrappers still produce undefined results when the
884 -- second argument (the shift amount) is negative.
886 -- | Shift the argument left by the specified number of bits
887 -- (which must be non-negative).
888 shiftL# :: Word# -> Int# -> Word#
889 a `shiftL#` b | b >=# WORD_SIZE_IN_BITS# = int2Word# 0#
890 | otherwise = a `uncheckedShiftL#` b
892 -- | Shift the argument right by the specified number of bits
893 -- (which must be non-negative).
894 shiftRL# :: Word# -> Int# -> Word#
895 a `shiftRL#` b | b >=# WORD_SIZE_IN_BITS# = int2Word# 0#
896 | otherwise = a `uncheckedShiftRL#` b
898 -- | Shift the argument left by the specified number of bits
899 -- (which must be non-negative).
900 iShiftL# :: Int# -> Int# -> Int#
901 a `iShiftL#` b | b >=# WORD_SIZE_IN_BITS# = 0#
902 | otherwise = a `uncheckedIShiftL#` b
904 -- | Shift the argument right (signed) by the specified number of bits
905 -- (which must be non-negative).
906 iShiftRA# :: Int# -> Int# -> Int#
907 a `iShiftRA#` b | b >=# WORD_SIZE_IN_BITS# = if a <# 0# then (-1#) else 0#
908 | otherwise = a `uncheckedIShiftRA#` b
910 -- | Shift the argument right (unsigned) by the specified number of bits
911 -- (which must be non-negative).
912 iShiftRL# :: Int# -> Int# -> Int#
913 a `iShiftRL#` b | b >=# WORD_SIZE_IN_BITS# = 0#
914 | otherwise = a `uncheckedIShiftRL#` b
916 #if WORD_SIZE_IN_BITS == 32
918 "narrow32Int#" forall x#. narrow32Int# x# = x#
919 "narrow32Word#" forall x#. narrow32Word# x# = x#
924 "int2Word2Int" forall x#. int2Word# (word2Int# x#) = x#
925 "word2Int2Word" forall x#. word2Int# (int2Word# x#) = x#
930 %********************************************************
932 \subsection{Unpacking C strings}
934 %********************************************************
936 This code is needed for virtually all programs, since it's used for
937 unpacking the strings of error messages.
940 unpackCString# :: Addr# -> [Char]
941 {-# NOINLINE [1] unpackCString# #-}
946 | ch `eqChar#` '\0'# = []
947 | otherwise = C# ch : unpack (nh +# 1#)
949 ch = indexCharOffAddr# addr nh
951 unpackAppendCString# :: Addr# -> [Char] -> [Char]
952 unpackAppendCString# addr rest
956 | ch `eqChar#` '\0'# = rest
957 | otherwise = C# ch : unpack (nh +# 1#)
959 ch = indexCharOffAddr# addr nh
961 unpackFoldrCString# :: Addr# -> (Char -> a -> a) -> a -> a
962 {-# NOINLINE [0] unpackFoldrCString# #-}
963 -- Don't inline till right at the end;
964 -- usually the unpack-list rule turns it into unpackCStringList
965 unpackFoldrCString# addr f z
969 | ch `eqChar#` '\0'# = z
970 | otherwise = C# ch `f` unpack (nh +# 1#)
972 ch = indexCharOffAddr# addr nh
974 unpackCStringUtf8# :: Addr# -> [Char]
975 unpackCStringUtf8# addr
979 | ch `eqChar#` '\0'# = []
980 | ch `leChar#` '\x7F'# = C# ch : unpack (nh +# 1#)
981 | ch `leChar#` '\xDF'# =
982 C# (chr# (((ord# ch -# 0xC0#) `uncheckedIShiftL#` 6#) +#
983 (ord# (indexCharOffAddr# addr (nh +# 1#)) -# 0x80#))) :
985 | ch `leChar#` '\xEF'# =
986 C# (chr# (((ord# ch -# 0xE0#) `uncheckedIShiftL#` 12#) +#
987 ((ord# (indexCharOffAddr# addr (nh +# 1#)) -# 0x80#) `uncheckedIShiftL#` 6#) +#
988 (ord# (indexCharOffAddr# addr (nh +# 2#)) -# 0x80#))) :
991 C# (chr# (((ord# ch -# 0xF0#) `uncheckedIShiftL#` 18#) +#
992 ((ord# (indexCharOffAddr# addr (nh +# 1#)) -# 0x80#) `uncheckedIShiftL#` 12#) +#
993 ((ord# (indexCharOffAddr# addr (nh +# 2#)) -# 0x80#) `uncheckedIShiftL#` 6#) +#
994 (ord# (indexCharOffAddr# addr (nh +# 3#)) -# 0x80#))) :
997 ch = indexCharOffAddr# addr nh
999 unpackNBytes# :: Addr# -> Int# -> [Char]
1000 unpackNBytes# _addr 0# = []
1001 unpackNBytes# addr len# = unpack [] (len# -# 1#)
1006 case indexCharOffAddr# addr i# of
1007 ch -> unpack (C# ch : acc) (i# -# 1#)
1010 "unpack" [~1] forall a . unpackCString# a = build (unpackFoldrCString# a)
1011 "unpack-list" [1] forall a . unpackFoldrCString# a (:) [] = unpackCString# a
1012 "unpack-append" forall a n . unpackFoldrCString# a (:) n = unpackAppendCString# a n
1014 -- There's a built-in rule (in PrelRules.lhs) for
1015 -- unpackFoldr "foo" c (unpackFoldr "baz" c n) = unpackFoldr "foobaz" c n
1022 -- | A special argument for the 'Control.Monad.ST.ST' type constructor,
1023 -- indexing a state embedded in the 'Prelude.IO' monad by
1024 -- 'Control.Monad.ST.stToIO'.