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 Classes: CCallable, CReturnable
21 GHC.Base Classes: Eq, Ord, Functor, Monad
22 Types: list, (), Int, Bool, Ordering, Char, String
24 Data.Tup Types: tuples, plus instances for GHC.Base classes
26 GHC.Show Class: Show, plus instances for GHC.Base/GHC.Tup types
28 GHC.Enum Class: Enum, plus instances for GHC.Base/GHC.Tup types
30 Data.Maybe Type: Maybe, plus instances for GHC.Base classes
32 GHC.Num Class: Num, plus instances for Int
33 Type: Integer, plus instances for all classes so far (Eq, Ord, Num, Show)
35 Integer is needed here because it is mentioned in the signature
36 of 'fromInteger' in class Num
38 GHC.Real Classes: Real, Integral, Fractional, RealFrac
39 plus instances for Int, Integer
40 Types: Ratio, Rational
41 plus intances for classes so far
43 Rational is needed here because it is mentioned in the signature
44 of 'toRational' in class Real
46 Ix Classes: Ix, plus instances for Int, Bool, Char, Integer, Ordering, tuples
48 GHC.Arr Types: Array, MutableArray, MutableVar
50 Does *not* contain any ByteArray stuff (see GHC.ByteArr)
51 Arrays are used by a function in GHC.Float
53 GHC.Float Classes: Floating, RealFloat
54 Types: Float, Double, plus instances of all classes so far
56 This module contains everything to do with floating point.
57 It is a big module (900 lines)
58 With a bit of luck, many modules can be compiled without ever reading GHC.Float.hi
60 GHC.ByteArr Types: ByteArray, MutableByteArray
62 We want this one to be after GHC.Float, because it defines arrays
66 Other Prelude modules are much easier with fewer complex dependencies.
69 {-# OPTIONS -fno-implicit-prelude #-}
70 -----------------------------------------------------------------------------
73 -- Copyright : (c) The University of Glasgow, 1992-2002
74 -- License : see libraries/base/LICENSE
76 -- Maintainer : cvs-ghc@haskell.org
77 -- Stability : internal
78 -- Portability : non-portable (GHC extensions)
80 -- Basic data types and classes.
82 -----------------------------------------------------------------------------
89 module GHC.Prim, -- Re-export GHC.Prim and GHC.Err, to avoid lots
90 module GHC.Err -- of people having to import it explicitly
95 import {-# SOURCE #-} GHC.Err
99 infix 4 ==, /=, <, <=, >=, >
105 default () -- Double isn't available yet
109 %*********************************************************
111 \subsection{DEBUGGING STUFF}
112 %* (for use when compiling GHC.Base itself doesn't work)
114 %*********************************************************
118 data Bool = False | True
119 data Ordering = LT | EQ | GT
127 (&&) True True = True
133 unpackCString# :: Addr# -> [Char]
134 unpackFoldrCString# :: Addr# -> (Char -> a -> a) -> a -> a
135 unpackAppendCString# :: Addr# -> [Char] -> [Char]
136 unpackCStringUtf8# :: Addr# -> [Char]
137 unpackCString# a = error "urk"
138 unpackFoldrCString# a = error "urk"
139 unpackAppendCString# a = error "urk"
140 unpackCStringUtf8# a = error "urk"
145 %*********************************************************
147 \subsection{Standard classes @Eq@, @Ord@}
149 %*********************************************************
153 -- | The 'Eq' class defines equality ('==') and inequality ('/=').
154 -- All the basic datatypes exported by the "Prelude" are instances of 'Eq',
155 -- and 'Eq' may be derived for any datatype whose constituents are also
156 -- instances of 'Eq'.
158 -- Minimal complete definition: either '==' or '/='.
161 (==), (/=) :: a -> a -> Bool
163 x /= y = not (x == y)
164 x == y = not (x /= y)
166 class (Eq a) => Ord a where
167 compare :: a -> a -> Ordering
168 (<), (<=), (>), (>=) :: a -> a -> Bool
169 max, min :: a -> a -> a
171 -- An instance of Ord should define either 'compare' or '<='.
172 -- Using 'compare' can be more efficient for complex types.
176 | x <= y = LT -- NB: must be '<=' not '<' to validate the
177 -- above claim about the minimal things that
178 -- can be defined for an instance of Ord
181 x < y = case compare x y of { LT -> True; _other -> False }
182 x <= y = case compare x y of { GT -> False; _other -> True }
183 x > y = case compare x y of { GT -> True; _other -> False }
184 x >= y = case compare x y of { LT -> False; _other -> True }
186 -- These two default methods use '<=' rather than 'compare'
187 -- because the latter is often more expensive
188 max x y = if x <= y then y else x
189 min x y = if x <= y then x else y
192 %*********************************************************
194 \subsection{Monadic classes @Functor@, @Monad@ }
196 %*********************************************************
199 {- | The 'Functor' class is used for types that can be mapped over.
200 Instances of 'Functor' should satisfy the following laws:
203 > fmap (f . g) == fmap f . fmap g
205 The instances of 'Functor' for lists, 'Maybe' and 'IO' defined in the "Prelude"
209 class Functor f where
210 fmap :: (a -> b) -> f a -> f b
212 {- | The 'Monad' class defines the basic operations over a /monad/.
213 Instances of 'Monad' should satisfy the following laws:
215 > return a >>= k == k a
217 > m >>= (\x -> k x >>= h) == (m >>= k) >>= h
219 Instances of both 'Monad' and 'Functor' should additionally satisfy the law:
221 > fmap f xs == xs >>= return . f
223 The instances of 'Monad' for lists, 'Maybe' and 'IO' defined in the "Prelude"
228 (>>=) :: m a -> (a -> m b) -> m b
229 (>>) :: m a -> m b -> m b
231 fail :: String -> m a
233 m >> k = m >>= \_ -> k
238 %*********************************************************
240 \subsection{The list type}
242 %*********************************************************
245 data [] a = [] | a : [a] -- do explicitly: deriving (Eq, Ord)
246 -- to avoid weird names like con2tag_[]#
249 instance (Eq a) => Eq [a] where
250 {-# SPECIALISE instance Eq [Char] #-}
252 (x:xs) == (y:ys) = x == y && xs == ys
255 instance (Ord a) => Ord [a] where
256 {-# SPECIALISE instance Ord [Char] #-}
258 compare [] (_:_) = LT
259 compare (_:_) [] = GT
260 compare (x:xs) (y:ys) = case compare x y of
264 instance Functor [] where
267 instance Monad [] where
268 m >>= k = foldr ((++) . k) [] m
269 m >> k = foldr ((++) . (\ _ -> k)) [] m
274 A few list functions that appear here because they are used here.
275 The rest of the prelude list functions are in GHC.List.
277 ----------------------------------------------
278 -- foldr/build/augment
279 ----------------------------------------------
282 foldr :: (a -> b -> b) -> b -> [a] -> b
284 -- foldr f z (x:xs) = f x (foldr f z xs)
285 {-# INLINE [0] foldr #-}
286 -- Inline only in the final stage, after the foldr/cons rule has had a chance
290 go (y:ys) = y `k` go ys
292 build :: forall a. (forall b. (a -> b -> b) -> b -> b) -> [a]
293 {-# INLINE [1] build #-}
294 -- The INLINE is important, even though build is tiny,
295 -- because it prevents [] getting inlined in the version that
296 -- appears in the interface file. If [] *is* inlined, it
297 -- won't match with [] appearing in rules in an importing module.
299 -- The "1" says to inline in phase 1
303 augment :: forall a. (forall b. (a->b->b) -> b -> b) -> [a] -> [a]
304 {-# INLINE [1] augment #-}
305 augment g xs = g (:) xs
308 "fold/build" forall k z (g::forall b. (a->b->b) -> b -> b) .
309 foldr k z (build g) = g k z
311 "foldr/augment" forall k z xs (g::forall b. (a->b->b) -> b -> b) .
312 foldr k z (augment g xs) = g k (foldr k z xs)
314 "foldr/id" foldr (:) [] = \x->x
315 "foldr/app" [1] forall xs ys. foldr (:) ys xs = xs ++ ys
316 -- Only activate this from phase 1, because that's
317 -- when we disable the rule that expands (++) into foldr
319 -- The foldr/cons rule looks nice, but it can give disastrously
320 -- bloated code when commpiling
321 -- array (a,b) [(1,2), (2,2), (3,2), ...very long list... ]
322 -- i.e. when there are very very long literal lists
323 -- So I've disabled it for now. We could have special cases
324 -- for short lists, I suppose.
325 -- "foldr/cons" forall k z x xs. foldr k z (x:xs) = k x (foldr k z xs)
327 "foldr/single" forall k z x. foldr k z [x] = k x z
328 "foldr/nil" forall k z. foldr k z [] = z
330 "augment/build" forall (g::forall b. (a->b->b) -> b -> b)
331 (h::forall b. (a->b->b) -> b -> b) .
332 augment g (build h) = build (\c n -> g c (h c n))
333 "augment/nil" forall (g::forall b. (a->b->b) -> b -> b) .
334 augment g [] = build g
337 -- This rule is true, but not (I think) useful:
338 -- augment g (augment h t) = augment (\cn -> g c (h c n)) t
342 ----------------------------------------------
344 ----------------------------------------------
347 map :: (a -> b) -> [a] -> [b]
349 map f (x:xs) = f x : map f xs
352 mapFB :: (elt -> lst -> lst) -> (a -> elt) -> a -> lst -> lst
353 {-# INLINE [0] mapFB #-}
354 mapFB c f x ys = c (f x) ys
356 -- The rules for map work like this.
358 -- Up to (but not including) phase 1, we use the "map" rule to
359 -- rewrite all saturated applications of map with its build/fold
360 -- form, hoping for fusion to happen.
361 -- In phase 1 and 0, we switch off that rule, inline build, and
362 -- switch on the "mapList" rule, which rewrites the foldr/mapFB
363 -- thing back into plain map.
365 -- It's important that these two rules aren't both active at once
366 -- (along with build's unfolding) else we'd get an infinite loop
367 -- in the rules. Hence the activation control below.
369 -- The "mapFB" rule optimises compositions of map.
371 -- This same pattern is followed by many other functions:
372 -- e.g. append, filter, iterate, repeat, etc.
375 "map" [~1] forall f xs. map f xs = build (\c n -> foldr (mapFB c f) n xs)
376 "mapList" [1] forall f. foldr (mapFB (:) f) [] = map f
377 "mapFB" forall c f g. mapFB (mapFB c f) g = mapFB c (f.g)
382 ----------------------------------------------
384 ----------------------------------------------
386 (++) :: [a] -> [a] -> [a]
388 (++) (x:xs) ys = x : xs ++ ys
391 "++" [~1] forall xs ys. xs ++ ys = augment (\c n -> foldr c n xs) ys
397 %*********************************************************
399 \subsection{Type @Bool@}
401 %*********************************************************
404 -- |The 'Bool' type is an enumeration. It is defined with 'False'
405 -- first so that the corresponding 'Enum' instance will give @'fromEnum'
406 -- False@ the value zero, and @'fromEnum' True@ the value 1.
407 data Bool = False | True deriving (Eq, Ord)
408 -- Read in GHC.Read, Show in GHC.Show
413 (&&) :: Bool -> Bool -> Bool
418 (||) :: Bool -> Bool -> Bool
427 -- |'otherwise' is defined as the value 'True'. It helps to make
428 -- guards more readable. eg.
430 -- > f x | x < 0 = ...
431 -- > | otherwise = ...
437 %*********************************************************
439 \subsection{The @()@ type}
441 %*********************************************************
443 The Unit type is here because virtually any program needs it (whereas
444 some programs may get away without consulting GHC.Tup). Furthermore,
445 the renamer currently *always* asks for () to be in scope, so that
446 ccalls can use () as their default type; so when compiling GHC.Base we
447 need (). (We could arrange suck in () only if -fglasgow-exts, but putting
448 it here seems more direct.)
451 -- | The unit datatype @()@ has one non-undefined member, the nullary
459 instance Ord () where
470 %*********************************************************
472 \subsection{Type @Ordering@}
474 %*********************************************************
477 -- | Represents an ordering relationship between two values: less
478 -- than, equal to, or greater than. An 'Ordering' is returned by
480 data Ordering = LT | EQ | GT deriving (Eq, Ord)
481 -- Read in GHC.Read, Show in GHC.Show
485 %*********************************************************
487 \subsection{Type @Char@ and @String@}
489 %*********************************************************
492 -- | A 'String' is a list of characters. String constants in Haskell are values
497 {-| The character type 'Char' is an enumeration whose values represent
498 Unicode characters. A character literal in Haskell has type 'Char'.
500 To convert a 'Char' to or from an 'Int', use 'Prelude.toEnum' and
501 'Prelude.fromEnum' from the 'Enum' class respectively (equivalently
502 'ord' and 'chr' also do the trick).
506 -- We don't use deriving for Eq and Ord, because for Ord the derived
507 -- instance defines only compare, which takes two primops. Then
508 -- '>' uses compare, and therefore takes two primops instead of one.
510 instance Eq Char where
511 (C# c1) == (C# c2) = c1 `eqChar#` c2
512 (C# c1) /= (C# c2) = c1 `neChar#` c2
514 instance Ord Char where
515 (C# c1) > (C# c2) = c1 `gtChar#` c2
516 (C# c1) >= (C# c2) = c1 `geChar#` c2
517 (C# c1) <= (C# c2) = c1 `leChar#` c2
518 (C# c1) < (C# c2) = c1 `ltChar#` c2
521 "x# `eqChar#` x#" forall x#. x# `eqChar#` x# = True
522 "x# `neChar#` x#" forall x#. x# `neChar#` x# = False
523 "x# `gtChar#` x#" forall x#. x# `gtChar#` x# = False
524 "x# `geChar#` x#" forall x#. x# `geChar#` x# = True
525 "x# `leChar#` x#" forall x#. x# `leChar#` x# = True
526 "x# `ltChar#` x#" forall x#. x# `ltChar#` x# = False
530 chr (I# i#) | int2Word# i# `leWord#` int2Word# 0x10FFFF# = C# (chr# i#)
531 | otherwise = error "Prelude.chr: bad argument"
533 unsafeChr :: Int -> Char
534 unsafeChr (I# i#) = C# (chr# i#)
537 ord (C# c#) = I# (ord# c#)
540 String equality is used when desugaring pattern-matches against strings.
543 eqString :: String -> String -> Bool
544 eqString [] [] = True
545 eqString (c1:cs1) (c2:cs2) = c1 == c2 && cs1 `eqString` cs2
546 eqString cs1 cs2 = False
548 {-# RULES "eqString" (==) = eqString #-}
552 %*********************************************************
554 \subsection{Type @Int@}
556 %*********************************************************
560 -- ^A fixed-precision integer type with at least the range @[-2^29
561 -- .. 2^29-1]@. The exact range for a given implementation can be
562 -- determined by using 'minBound' and 'maxBound' from the 'Bounded'
565 zeroInt, oneInt, twoInt, maxInt, minInt :: Int
570 {- Seems clumsy. Should perhaps put minInt and MaxInt directly into MachDeps.h -}
571 #if WORD_SIZE_IN_BITS == 31
572 minInt = I# (-0x40000000#)
573 maxInt = I# 0x3FFFFFFF#
574 #elif WORD_SIZE_IN_BITS == 32
575 minInt = I# (-0x80000000#)
576 maxInt = I# 0x7FFFFFFF#
578 minInt = I# (-0x8000000000000000#)
579 maxInt = I# 0x7FFFFFFFFFFFFFFF#
582 instance Eq Int where
586 instance Ord Int where
593 compareInt :: Int -> Int -> Ordering
594 (I# x#) `compareInt` (I# y#) = compareInt# x# y#
596 compareInt# :: Int# -> Int# -> Ordering
604 %*********************************************************
606 \subsection{The function type}
608 %*********************************************************
615 -- lazy function; this is just the same as id, but its unfolding
616 -- and strictness are over-ridden by the definition in MkId.lhs
617 -- That way, it does not get inlined, and the strictness analyser
618 -- sees it as lazy. Then the worker/wrapper phase inlines it.
623 -- Assertion function. This simply ignores its boolean argument.
624 -- The compiler may rewrite it to (assertError line)
625 -- SLPJ: in 5.04 etc 'assert' is in GHC.Prim,
626 -- but from Template Haskell onwards it's simply
627 -- defined here in Base.lhs
628 assert :: Bool -> a -> a
635 -- function composition
637 (.) :: (b -> c) -> (a -> b) -> a -> c
640 -- flip f takes its (first) two arguments in the reverse order of f.
641 flip :: (a -> b -> c) -> b -> a -> c
644 -- right-associating infix application operator (useful in continuation-
647 ($) :: (a -> b) -> a -> b
650 -- until p f yields the result of applying f until p holds.
651 until :: (a -> Bool) -> (a -> a) -> a -> a
652 until p f x | p x = x
653 | otherwise = until p f (f x)
655 -- asTypeOf is a type-restricted version of const. It is usually used
656 -- as an infix operator, and its typing forces its first argument
657 -- (which is usually overloaded) to have the same type as the second.
658 asTypeOf :: a -> a -> a
662 %*********************************************************
664 \subsection{CCallable instances}
666 %*********************************************************
668 Defined here to avoid orphans
671 instance CCallable Char
672 instance CReturnable Char
674 instance CCallable Int
675 instance CReturnable Int
677 instance CReturnable () -- Why, exactly?
681 %*********************************************************
683 \subsection{Generics}
685 %*********************************************************
690 data (:+:) a b = Inl a | Inr b
691 data (:*:) a b = a :*: b
695 %*********************************************************
697 \subsection{@getTag@}
699 %*********************************************************
701 Returns the 'tag' of a constructor application; this function is used
702 by the deriving code for Eq, Ord and Enum.
704 The primitive dataToTag# requires an evaluated constructor application
705 as its argument, so we provide getTag as a wrapper that performs the
706 evaluation before calling dataToTag#. We could have dataToTag#
707 evaluate its argument, but we prefer to do it this way because (a)
708 dataToTag# can be an inline primop if it doesn't need to do any
709 evaluation, and (b) we want to expose the evaluation to the
710 simplifier, because it might be possible to eliminate the evaluation
711 in the case when the argument is already known to be evaluated.
714 {-# INLINE getTag #-}
716 getTag x = x `seq` dataToTag# x
719 %*********************************************************
721 \subsection{Numeric primops}
723 %*********************************************************
726 divInt# :: Int# -> Int# -> Int#
728 -- Be careful NOT to overflow if we do any additional arithmetic
729 -- on the arguments... the following previous version of this
730 -- code has problems with overflow:
731 -- | (x# ># 0#) && (y# <# 0#) = ((x# -# y#) -# 1#) `quotInt#` y#
732 -- | (x# <# 0#) && (y# ># 0#) = ((x# -# y#) +# 1#) `quotInt#` y#
733 | (x# ># 0#) && (y# <# 0#) = ((x# -# 1#) `quotInt#` y#) -# 1#
734 | (x# <# 0#) && (y# ># 0#) = ((x# +# 1#) `quotInt#` y#) -# 1#
735 | otherwise = x# `quotInt#` y#
737 modInt# :: Int# -> Int# -> Int#
739 | (x# ># 0#) && (y# <# 0#) ||
740 (x# <# 0#) && (y# ># 0#) = if r# /=# 0# then r# +# y# else 0#
746 Definitions of the boxed PrimOps; these will be
747 used in the case of partial applications, etc.
756 {-# INLINE plusInt #-}
757 {-# INLINE minusInt #-}
758 {-# INLINE timesInt #-}
759 {-# INLINE quotInt #-}
760 {-# INLINE remInt #-}
761 {-# INLINE negateInt #-}
763 plusInt, minusInt, timesInt, quotInt, remInt, divInt, modInt, gcdInt :: Int -> Int -> Int
764 (I# x) `plusInt` (I# y) = I# (x +# y)
765 (I# x) `minusInt` (I# y) = I# (x -# y)
766 (I# x) `timesInt` (I# y) = I# (x *# y)
767 (I# x) `quotInt` (I# y) = I# (x `quotInt#` y)
768 (I# x) `remInt` (I# y) = I# (x `remInt#` y)
769 (I# x) `divInt` (I# y) = I# (x `divInt#` y)
770 (I# x) `modInt` (I# y) = I# (x `modInt#` y)
773 "x# +# 0#" forall x#. x# +# 0# = x#
774 "0# +# x#" forall x#. 0# +# x# = x#
775 "x# -# 0#" forall x#. x# -# 0# = x#
776 "x# -# x#" forall x#. x# -# x# = 0#
777 "x# *# 0#" forall x#. x# *# 0# = 0#
778 "0# *# x#" forall x#. 0# *# x# = 0#
779 "x# *# 1#" forall x#. x# *# 1# = x#
780 "1# *# x#" forall x#. 1# *# x# = x#
783 gcdInt (I# a) (I# b) = g a b
784 where g 0# 0# = error "GHC.Base.gcdInt: gcd 0 0 is undefined"
787 g _ _ = I# (gcdInt# absA absB)
789 absInt x = if x <# 0# then negateInt# x else x
794 negateInt :: Int -> Int
795 negateInt (I# x) = I# (negateInt# x)
797 gtInt, geInt, eqInt, neInt, ltInt, leInt :: Int -> Int -> Bool
798 (I# x) `gtInt` (I# y) = x ># y
799 (I# x) `geInt` (I# y) = x >=# y
800 (I# x) `eqInt` (I# y) = x ==# y
801 (I# x) `neInt` (I# y) = x /=# y
802 (I# x) `ltInt` (I# y) = x <# y
803 (I# x) `leInt` (I# y) = x <=# y
806 "x# ># x#" forall x#. x# ># x# = False
807 "x# >=# x#" forall x#. x# >=# x# = True
808 "x# ==# x#" forall x#. x# ==# x# = True
809 "x# /=# x#" forall x#. x# /=# x# = False
810 "x# <# x#" forall x#. x# <# x# = False
811 "x# <=# x#" forall x#. x# <=# x# = True
815 "plusFloat x 0.0" forall x#. plusFloat# x# 0.0# = x#
816 "plusFloat 0.0 x" forall x#. plusFloat# 0.0# x# = x#
817 "minusFloat x 0.0" forall x#. minusFloat# x# 0.0# = x#
818 "minusFloat x x" forall x#. minusFloat# x# x# = 0.0#
819 "timesFloat x 0.0" forall x#. timesFloat# x# 0.0# = 0.0#
820 "timesFloat0.0 x" forall x#. timesFloat# 0.0# x# = 0.0#
821 "timesFloat x 1.0" forall x#. timesFloat# x# 1.0# = x#
822 "timesFloat 1.0 x" forall x#. timesFloat# 1.0# x# = x#
823 "divideFloat x 1.0" forall x#. divideFloat# x# 1.0# = x#
827 "plusDouble x 0.0" forall x#. (+##) x# 0.0## = x#
828 "plusDouble 0.0 x" forall x#. (+##) 0.0## x# = x#
829 "minusDouble x 0.0" forall x#. (-##) x# 0.0## = x#
830 "minusDouble x x" forall x#. (-##) x# x# = 0.0##
831 "timesDouble x 0.0" forall x#. (*##) x# 0.0## = 0.0##
832 "timesDouble 0.0 x" forall x#. (*##) 0.0## x# = 0.0##
833 "timesDouble x 1.0" forall x#. (*##) x# 1.0## = x#
834 "timesDouble 1.0 x" forall x#. (*##) 1.0## x# = x#
835 "divideDouble x 1.0" forall x#. (/##) x# 1.0## = x#
838 -- Wrappers for the shift operations. The uncheckedShift# family are
839 -- undefined when the amount being shifted by is greater than the size
840 -- in bits of Int#, so these wrappers perform a check and return
841 -- either zero or -1 appropriately.
843 -- Note that these wrappers still produce undefined results when the
844 -- second argument (the shift amount) is negative.
846 shiftL#, shiftRL# :: Word# -> Int# -> Word#
848 a `shiftL#` b | b >=# WORD_SIZE_IN_BITS# = int2Word# 0#
849 | otherwise = a `uncheckedShiftL#` b
851 a `shiftRL#` b | b >=# WORD_SIZE_IN_BITS# = int2Word# 0#
852 | otherwise = a `uncheckedShiftRL#` b
854 iShiftL#, iShiftRA#, iShiftRL# :: Int# -> Int# -> Int#
856 a `iShiftL#` b | b >=# WORD_SIZE_IN_BITS# = 0#
857 | otherwise = a `uncheckedIShiftL#` b
859 a `iShiftRA#` b | b >=# WORD_SIZE_IN_BITS# = if a <# 0# then (-1#) else 0#
860 | otherwise = a `uncheckedIShiftRA#` b
862 a `iShiftRL#` b | b >=# WORD_SIZE_IN_BITS# = 0#
863 | otherwise = a `uncheckedIShiftRL#` b
865 #if WORD_SIZE_IN_BITS == 32
867 "narrow32Int#" forall x#. narrow32Int# x# = x#
868 "narrow32Word#" forall x#. narrow32Word# x# = x#
873 "int2Word2Int" forall x#. int2Word# (word2Int# x#) = x#
874 "word2Int2Word" forall x#. word2Int# (int2Word# x#) = x#
879 %********************************************************
881 \subsection{Unpacking C strings}
883 %********************************************************
885 This code is needed for virtually all programs, since it's used for
886 unpacking the strings of error messages.
889 unpackCString# :: Addr# -> [Char]
890 {-# NOINLINE [1] unpackCString# #-}
895 | ch `eqChar#` '\0'# = []
896 | otherwise = C# ch : unpack (nh +# 1#)
898 ch = indexCharOffAddr# addr nh
900 unpackAppendCString# :: Addr# -> [Char] -> [Char]
901 unpackAppendCString# addr rest
905 | ch `eqChar#` '\0'# = rest
906 | otherwise = C# ch : unpack (nh +# 1#)
908 ch = indexCharOffAddr# addr nh
910 unpackFoldrCString# :: Addr# -> (Char -> a -> a) -> a -> a
911 {-# NOINLINE [0] unpackFoldrCString# #-}
912 -- Don't inline till right at the end;
913 -- usually the unpack-list rule turns it into unpackCStringList
914 unpackFoldrCString# addr f z
918 | ch `eqChar#` '\0'# = z
919 | otherwise = C# ch `f` unpack (nh +# 1#)
921 ch = indexCharOffAddr# addr nh
923 unpackCStringUtf8# :: Addr# -> [Char]
924 unpackCStringUtf8# addr
928 | ch `eqChar#` '\0'# = []
929 | ch `leChar#` '\x7F'# = C# ch : unpack (nh +# 1#)
930 | ch `leChar#` '\xDF'# =
931 C# (chr# (((ord# ch -# 0xC0#) `uncheckedIShiftL#` 6#) +#
932 (ord# (indexCharOffAddr# addr (nh +# 1#)) -# 0x80#))) :
934 | ch `leChar#` '\xEF'# =
935 C# (chr# (((ord# ch -# 0xE0#) `uncheckedIShiftL#` 12#) +#
936 ((ord# (indexCharOffAddr# addr (nh +# 1#)) -# 0x80#) `uncheckedIShiftL#` 6#) +#
937 (ord# (indexCharOffAddr# addr (nh +# 2#)) -# 0x80#))) :
940 C# (chr# (((ord# ch -# 0xF0#) `uncheckedIShiftL#` 18#) +#
941 ((ord# (indexCharOffAddr# addr (nh +# 1#)) -# 0x80#) `uncheckedIShiftL#` 12#) +#
942 ((ord# (indexCharOffAddr# addr (nh +# 2#)) -# 0x80#) `uncheckedIShiftL#` 6#) +#
943 (ord# (indexCharOffAddr# addr (nh +# 3#)) -# 0x80#))) :
946 ch = indexCharOffAddr# addr nh
948 unpackNBytes# :: Addr# -> Int# -> [Char]
949 unpackNBytes# _addr 0# = []
950 unpackNBytes# addr len# = unpack [] (len# -# 1#)
955 case indexCharOffAddr# addr i# of
956 ch -> unpack (C# ch : acc) (i# -# 1#)
959 "unpack" [~1] forall a . unpackCString# a = build (unpackFoldrCString# a)
960 "unpack-list" [1] forall a . unpackFoldrCString# a (:) [] = unpackCString# a
961 "unpack-append" forall a n . unpackFoldrCString# a (:) n = unpackAppendCString# a n
963 -- There's a built-in rule (in PrelRules.lhs) for
964 -- unpackFoldr "foo" c (unpackFoldr "baz" c n) = unpackFoldr "foobaz" c n