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 -----------------------------------------------------------------------------
88 module GHC.Prim, -- Re-export GHC.Prim and GHC.Err, to avoid lots
89 module GHC.Err -- of people having to import it explicitly
94 import {-# SOURCE #-} GHC.Err
98 infix 4 ==, /=, <, <=, >=, >
104 default () -- Double isn't available yet
108 %*********************************************************
110 \subsection{DEBUGGING STUFF}
111 %* (for use when compiling GHC.Base itself doesn't work)
113 %*********************************************************
117 data Bool = False | True
118 data Ordering = LT | EQ | GT
126 (&&) True True = True
132 unpackCString# :: Addr# -> [Char]
133 unpackFoldrCString# :: Addr# -> (Char -> a -> a) -> a -> a
134 unpackAppendCString# :: Addr# -> [Char] -> [Char]
135 unpackCStringUtf8# :: Addr# -> [Char]
136 unpackCString# a = error "urk"
137 unpackFoldrCString# a = error "urk"
138 unpackAppendCString# a = error "urk"
139 unpackCStringUtf8# a = error "urk"
144 %*********************************************************
146 \subsection{Standard classes @Eq@, @Ord@}
148 %*********************************************************
152 -- | The 'Eq' class defines equality ('==') and inequality ('/=').
153 -- All the basic datatypes exported by the "Prelude" are instances of 'Eq',
154 -- and 'Eq' may be derived for any datatype whose constituents are also
155 -- instances of 'Eq'.
157 -- Minimal complete definition: either '==' or '/='.
160 (==), (/=) :: a -> a -> Bool
162 x /= y = not (x == y)
163 x == y = not (x /= y)
165 -- | The 'Ord' class is used for totally ordered datatypes.
167 -- Instances of 'Ord' can be derived for any user-defined
168 -- datatype whose constituent types are in 'Ord'. The declared order
169 -- of the constructors in the data declaration determines the ordering
170 -- in derived 'Ord' instances. The 'Ordering' datatype allows a single
171 -- comparison to determine the precise ordering of two objects.
173 -- Minimal complete definition: either 'compare' or '<='.
174 -- Using 'compare' can be more efficient for complex types.
176 class (Eq a) => Ord a where
177 compare :: a -> a -> Ordering
178 (<), (<=), (>), (>=) :: a -> a -> Bool
179 max, min :: a -> a -> a
183 | x <= y = LT -- NB: must be '<=' not '<' to validate the
184 -- above claim about the minimal things that
185 -- can be defined for an instance of Ord
188 x < y = case compare x y of { LT -> True; _other -> False }
189 x <= y = case compare x y of { GT -> False; _other -> True }
190 x > y = case compare x y of { GT -> True; _other -> False }
191 x >= y = case compare x y of { LT -> False; _other -> True }
193 -- These two default methods use '<=' rather than 'compare'
194 -- because the latter is often more expensive
195 max x y = if x <= y then y else x
196 min x y = if x <= y then x else y
199 %*********************************************************
201 \subsection{Monadic classes @Functor@, @Monad@ }
203 %*********************************************************
206 {- | The 'Functor' class is used for types that can be mapped over.
207 Instances of 'Functor' should satisfy the following laws:
210 > fmap (f . g) == fmap f . fmap g
212 The instances of 'Functor' for lists, 'Maybe' and 'IO' defined in the "Prelude"
216 class Functor f where
217 fmap :: (a -> b) -> f a -> f b
219 {- | The 'Monad' class defines the basic operations over a /monad/.
220 Instances of 'Monad' should satisfy the following laws:
222 > return a >>= k == k a
224 > m >>= (\x -> k x >>= h) == (m >>= k) >>= h
226 Instances of both 'Monad' and 'Functor' should additionally satisfy the law:
228 > fmap f xs == xs >>= return . f
230 The instances of 'Monad' for lists, 'Maybe' and 'IO' defined in the "Prelude"
235 (>>=) :: forall a b. m a -> (a -> m b) -> m b
236 (>>) :: forall a b. m a -> m b -> m b
237 -- Explicit for-alls so that we know what order to
238 -- give type arguments when desugaring
240 fail :: String -> m a
242 m >> k = m >>= \_ -> k
247 %*********************************************************
249 \subsection{The list type}
251 %*********************************************************
254 data [] a = [] | a : [a] -- do explicitly: deriving (Eq, Ord)
255 -- to avoid weird names like con2tag_[]#
258 instance (Eq a) => Eq [a] where
259 {-# SPECIALISE instance Eq [Char] #-}
261 (x:xs) == (y:ys) = x == y && xs == ys
264 instance (Ord a) => Ord [a] where
265 {-# SPECIALISE instance Ord [Char] #-}
267 compare [] (_:_) = LT
268 compare (_:_) [] = GT
269 compare (x:xs) (y:ys) = case compare x y of
273 instance Functor [] where
276 instance Monad [] where
277 m >>= k = foldr ((++) . k) [] m
278 m >> k = foldr ((++) . (\ _ -> k)) [] m
283 A few list functions that appear here because they are used here.
284 The rest of the prelude list functions are in GHC.List.
286 ----------------------------------------------
287 -- foldr/build/augment
288 ----------------------------------------------
291 -- | 'foldr', applied to a binary operator, a starting value (typically
292 -- the right-identity of the operator), and a list, reduces the list
293 -- using the binary operator, from right to left:
295 -- > foldr f z [x1, x2, ..., xn] == x1 `f` (x2 `f` ... (xn `f` z)...)
297 foldr :: (a -> b -> b) -> b -> [a] -> b
299 -- foldr f z (x:xs) = f x (foldr f z xs)
300 {-# INLINE [0] foldr #-}
301 -- Inline only in the final stage, after the foldr/cons rule has had a chance
305 go (y:ys) = y `k` go ys
307 -- | A list producer that can be fused with 'foldr'.
308 -- This function is merely
310 -- > build g = g (:) []
312 -- but GHC's simplifier will transform an expression of the form
313 -- @'foldr' k z ('build' g)@, which may arise after inlining, to @g k z@,
314 -- which avoids producing an intermediate list.
316 build :: forall a. (forall b. (a -> b -> b) -> b -> b) -> [a]
317 {-# INLINE [1] build #-}
318 -- The INLINE is important, even though build is tiny,
319 -- because it prevents [] getting inlined in the version that
320 -- appears in the interface file. If [] *is* inlined, it
321 -- won't match with [] appearing in rules in an importing module.
323 -- The "1" says to inline in phase 1
327 -- | A list producer that can be fused with 'foldr'.
328 -- This function is merely
330 -- > augment g xs = g (:) xs
332 -- but GHC's simplifier will transform an expression of the form
333 -- @'foldr' k z ('augment' g xs)@, which may arise after inlining, to
334 -- @g k ('foldr' k z xs)@, which avoids producing an intermediate list.
336 augment :: forall a. (forall b. (a->b->b) -> b -> b) -> [a] -> [a]
337 {-# INLINE [1] augment #-}
338 augment g xs = g (:) xs
341 "fold/build" forall k z (g::forall b. (a->b->b) -> b -> b) .
342 foldr k z (build g) = g k z
344 "foldr/augment" forall k z xs (g::forall b. (a->b->b) -> b -> b) .
345 foldr k z (augment g xs) = g k (foldr k z xs)
347 "foldr/id" foldr (:) [] = \x->x
348 "foldr/app" [1] forall xs ys. foldr (:) ys xs = xs ++ ys
349 -- Only activate this from phase 1, because that's
350 -- when we disable the rule that expands (++) into foldr
352 -- The foldr/cons rule looks nice, but it can give disastrously
353 -- bloated code when commpiling
354 -- array (a,b) [(1,2), (2,2), (3,2), ...very long list... ]
355 -- i.e. when there are very very long literal lists
356 -- So I've disabled it for now. We could have special cases
357 -- for short lists, I suppose.
358 -- "foldr/cons" forall k z x xs. foldr k z (x:xs) = k x (foldr k z xs)
360 "foldr/single" forall k z x. foldr k z [x] = k x z
361 "foldr/nil" forall k z. foldr k z [] = z
363 "augment/build" forall (g::forall b. (a->b->b) -> b -> b)
364 (h::forall b. (a->b->b) -> b -> b) .
365 augment g (build h) = build (\c n -> g c (h c n))
366 "augment/nil" forall (g::forall b. (a->b->b) -> b -> b) .
367 augment g [] = build g
370 -- This rule is true, but not (I think) useful:
371 -- augment g (augment h t) = augment (\cn -> g c (h c n)) t
375 ----------------------------------------------
377 ----------------------------------------------
380 -- | 'map' @f xs@ is the list obtained by applying @f@ to each element
383 -- > map f [x1, x2, ..., xn] == [f x1, f x2, ..., f xn]
384 -- > map f [x1, x2, ...] == [f x1, f x2, ...]
386 map :: (a -> b) -> [a] -> [b]
388 map f (x:xs) = f x : map f xs
391 mapFB :: (elt -> lst -> lst) -> (a -> elt) -> a -> lst -> lst
392 {-# INLINE [0] mapFB #-}
393 mapFB c f x ys = c (f x) ys
395 -- The rules for map work like this.
397 -- Up to (but not including) phase 1, we use the "map" rule to
398 -- rewrite all saturated applications of map with its build/fold
399 -- form, hoping for fusion to happen.
400 -- In phase 1 and 0, we switch off that rule, inline build, and
401 -- switch on the "mapList" rule, which rewrites the foldr/mapFB
402 -- thing back into plain map.
404 -- It's important that these two rules aren't both active at once
405 -- (along with build's unfolding) else we'd get an infinite loop
406 -- in the rules. Hence the activation control below.
408 -- The "mapFB" rule optimises compositions of map.
410 -- This same pattern is followed by many other functions:
411 -- e.g. append, filter, iterate, repeat, etc.
414 "map" [~1] forall f xs. map f xs = build (\c n -> foldr (mapFB c f) n xs)
415 "mapList" [1] forall f. foldr (mapFB (:) f) [] = map f
416 "mapFB" forall c f g. mapFB (mapFB c f) g = mapFB c (f.g)
421 ----------------------------------------------
423 ----------------------------------------------
425 -- | Append two lists, i.e.,
427 -- > [x1, ..., xm] ++ [y1, ..., yn] == [x1, ..., xm, y1, ..., yn]
428 -- > [x1, ..., xm] ++ [y1, ...] == [x1, ..., xm, y1, ...]
430 -- If the first list is not finite, the result is the first list.
432 (++) :: [a] -> [a] -> [a]
434 (++) (x:xs) ys = x : xs ++ ys
437 "++" [~1] forall xs ys. xs ++ ys = augment (\c n -> foldr c n xs) ys
443 %*********************************************************
445 \subsection{Type @Bool@}
447 %*********************************************************
450 -- |The 'Bool' type is an enumeration. It is defined with 'False'
451 -- first so that the corresponding 'Prelude.Enum' instance will give
452 -- 'Prelude.fromEnum' 'False' the value zero, and
453 -- 'Prelude.fromEnum' 'True' the value 1.
454 data Bool = False | True deriving (Eq, Ord)
455 -- Read in GHC.Read, Show in GHC.Show
460 (&&) :: Bool -> Bool -> Bool
465 (||) :: Bool -> Bool -> Bool
474 -- |'otherwise' is defined as the value 'True'. It helps to make
475 -- guards more readable. eg.
477 -- > f x | x < 0 = ...
478 -- > | otherwise = ...
484 %*********************************************************
486 \subsection{The @()@ type}
488 %*********************************************************
490 The Unit type is here because virtually any program needs it (whereas
491 some programs may get away without consulting GHC.Tup). Furthermore,
492 the renamer currently *always* asks for () to be in scope, so that
493 ccalls can use () as their default type; so when compiling GHC.Base we
494 need (). (We could arrange suck in () only if -fglasgow-exts, but putting
495 it here seems more direct.)
498 -- | The unit datatype @()@ has one non-undefined member, the nullary
506 instance Ord () where
517 %*********************************************************
519 \subsection{Type @Ordering@}
521 %*********************************************************
524 -- | Represents an ordering relationship between two values: less
525 -- than, equal to, or greater than. An 'Ordering' is returned by
527 data Ordering = LT | EQ | GT deriving (Eq, Ord)
528 -- Read in GHC.Read, Show in GHC.Show
532 %*********************************************************
534 \subsection{Type @Char@ and @String@}
536 %*********************************************************
539 -- | A 'String' is a list of characters. String constants in Haskell are values
544 {-| The character type 'Char' is an enumeration whose values represent
545 Unicode (or equivalently ISO 10646) characters.
546 This set extends the ISO 8859-1 (Latin-1) character set
547 (the first 256 charachers), which is itself an extension of the ASCII
548 character set (the first 128 characters).
549 A character literal in Haskell has type 'Char'.
551 To convert a 'Char' to or from the corresponding 'Int' value defined
552 by Unicode, use 'Prelude.toEnum' and 'Prelude.fromEnum' from the
553 'Prelude.Enum' class respectively (or equivalently 'ord' and 'chr').
557 -- We don't use deriving for Eq and Ord, because for Ord the derived
558 -- instance defines only compare, which takes two primops. Then
559 -- '>' uses compare, and therefore takes two primops instead of one.
561 instance Eq Char where
562 (C# c1) == (C# c2) = c1 `eqChar#` c2
563 (C# c1) /= (C# c2) = c1 `neChar#` c2
565 instance Ord Char where
566 (C# c1) > (C# c2) = c1 `gtChar#` c2
567 (C# c1) >= (C# c2) = c1 `geChar#` c2
568 (C# c1) <= (C# c2) = c1 `leChar#` c2
569 (C# c1) < (C# c2) = c1 `ltChar#` c2
572 "x# `eqChar#` x#" forall x#. x# `eqChar#` x# = True
573 "x# `neChar#` x#" forall x#. x# `neChar#` x# = False
574 "x# `gtChar#` x#" forall x#. x# `gtChar#` x# = False
575 "x# `geChar#` x#" forall x#. x# `geChar#` x# = True
576 "x# `leChar#` x#" forall x#. x# `leChar#` x# = True
577 "x# `ltChar#` x#" forall x#. x# `ltChar#` x# = False
580 -- | The 'Prelude.toEnum' method restricted to the type 'Data.Char.Char'.
582 chr (I# i#) | int2Word# i# `leWord#` int2Word# 0x10FFFF# = C# (chr# i#)
583 | otherwise = error "Prelude.chr: bad argument"
585 unsafeChr :: Int -> Char
586 unsafeChr (I# i#) = C# (chr# i#)
588 -- | The 'Prelude.fromEnum' method restricted to the type 'Data.Char.Char'.
590 ord (C# c#) = I# (ord# c#)
593 String equality is used when desugaring pattern-matches against strings.
596 eqString :: String -> String -> Bool
597 eqString [] [] = True
598 eqString (c1:cs1) (c2:cs2) = c1 == c2 && cs1 `eqString` cs2
599 eqString cs1 cs2 = False
601 {-# RULES "eqString" (==) = eqString #-}
605 %*********************************************************
607 \subsection{Type @Int@}
609 %*********************************************************
613 -- ^A fixed-precision integer type with at least the range @[-2^29 .. 2^29-1]@.
614 -- The exact range for a given implementation can be determined by using
615 -- 'Prelude.minBound' and 'Prelude.maxBound' from the 'Prelude.Bounded' class.
617 zeroInt, oneInt, twoInt, maxInt, minInt :: Int
622 {- Seems clumsy. Should perhaps put minInt and MaxInt directly into MachDeps.h -}
623 #if WORD_SIZE_IN_BITS == 31
624 minInt = I# (-0x40000000#)
625 maxInt = I# 0x3FFFFFFF#
626 #elif WORD_SIZE_IN_BITS == 32
627 minInt = I# (-0x80000000#)
628 maxInt = I# 0x7FFFFFFF#
630 minInt = I# (-0x8000000000000000#)
631 maxInt = I# 0x7FFFFFFFFFFFFFFF#
634 instance Eq Int where
638 instance Ord Int where
645 compareInt :: Int -> Int -> Ordering
646 (I# x#) `compareInt` (I# y#) = compareInt# x# y#
648 compareInt# :: Int# -> Int# -> Ordering
656 %*********************************************************
658 \subsection{The function type}
660 %*********************************************************
663 -- | Identity function.
667 -- lazy function; this is just the same as id, but its unfolding
668 -- and strictness are over-ridden by the definition in MkId.lhs
669 -- That way, it does not get inlined, and the strictness analyser
670 -- sees it as lazy. Then the worker/wrapper phase inlines it.
675 -- Assertion function. This simply ignores its boolean argument.
676 -- The compiler may rewrite it to @('assertError' line)@.
678 -- | If the first argument evaluates to 'True', then the result is the
679 -- second argument. Otherwise an 'AssertionFailed' exception is raised,
680 -- containing a 'String' with the source file and line number of the
683 -- Assertions can normally be turned on or off with a compiler flag
684 -- (for GHC, assertions are normally on unless the @-fignore-asserts@
685 -- option is given). When assertions are turned off, the first
686 -- argument to 'assert' is ignored, and the second argument is
687 -- returned as the result.
689 -- SLPJ: in 5.04 etc 'assert' is in GHC.Prim,
690 -- but from Template Haskell onwards it's simply
691 -- defined here in Base.lhs
692 assert :: Bool -> a -> a
695 -- | Constant function.
699 -- | Function composition.
701 (.) :: (b -> c) -> (a -> b) -> a -> c
704 -- | @'flip' f@ takes its (first) two arguments in the reverse order of @f@.
705 flip :: (a -> b -> c) -> b -> a -> c
708 -- | Application operator. This operator is redundant, since ordinary
709 -- application @(f x)@ means the same as @(f '$' x)@. However, '$' has
710 -- low, right-associative binding precedence, so it sometimes allows
711 -- parentheses to be omitted; for example:
713 -- > f $ g $ h x = f (g (h x))
715 -- It is also useful in higher-order situations, such as @'map' ('$' 0) xs@,
716 -- or @'Data.List.zipWith' ('$') fs xs@.
718 ($) :: (a -> b) -> a -> b
721 -- | @'until' p f@ yields the result of applying @f@ until @p@ holds.
722 until :: (a -> Bool) -> (a -> a) -> a -> a
723 until p f x | p x = x
724 | otherwise = until p f (f x)
726 -- | 'asTypeOf' is a type-restricted version of 'const'. It is usually
727 -- used as an infix operator, and its typing forces its first argument
728 -- (which is usually overloaded) to have the same type as the second.
729 asTypeOf :: a -> a -> a
733 %*********************************************************
735 \subsection{Generics}
737 %*********************************************************
742 data (:+:) a b = Inl a | Inr b
743 data (:*:) a b = a :*: b
747 %*********************************************************
749 \subsection{@getTag@}
751 %*********************************************************
753 Returns the 'tag' of a constructor application; this function is used
754 by the deriving code for Eq, Ord and Enum.
756 The primitive dataToTag# requires an evaluated constructor application
757 as its argument, so we provide getTag as a wrapper that performs the
758 evaluation before calling dataToTag#. We could have dataToTag#
759 evaluate its argument, but we prefer to do it this way because (a)
760 dataToTag# can be an inline primop if it doesn't need to do any
761 evaluation, and (b) we want to expose the evaluation to the
762 simplifier, because it might be possible to eliminate the evaluation
763 in the case when the argument is already known to be evaluated.
766 {-# INLINE getTag #-}
768 getTag x = x `seq` dataToTag# x
771 %*********************************************************
773 \subsection{Numeric primops}
775 %*********************************************************
778 divInt# :: Int# -> Int# -> Int#
780 -- Be careful NOT to overflow if we do any additional arithmetic
781 -- on the arguments... the following previous version of this
782 -- code has problems with overflow:
783 -- | (x# ># 0#) && (y# <# 0#) = ((x# -# y#) -# 1#) `quotInt#` y#
784 -- | (x# <# 0#) && (y# ># 0#) = ((x# -# y#) +# 1#) `quotInt#` y#
785 | (x# ># 0#) && (y# <# 0#) = ((x# -# 1#) `quotInt#` y#) -# 1#
786 | (x# <# 0#) && (y# ># 0#) = ((x# +# 1#) `quotInt#` y#) -# 1#
787 | otherwise = x# `quotInt#` y#
789 modInt# :: Int# -> Int# -> Int#
791 | (x# ># 0#) && (y# <# 0#) ||
792 (x# <# 0#) && (y# ># 0#) = if r# /=# 0# then r# +# y# else 0#
798 Definitions of the boxed PrimOps; these will be
799 used in the case of partial applications, etc.
808 {-# INLINE plusInt #-}
809 {-# INLINE minusInt #-}
810 {-# INLINE timesInt #-}
811 {-# INLINE quotInt #-}
812 {-# INLINE remInt #-}
813 {-# INLINE negateInt #-}
815 plusInt, minusInt, timesInt, quotInt, remInt, divInt, modInt, gcdInt :: Int -> Int -> Int
816 (I# x) `plusInt` (I# y) = I# (x +# y)
817 (I# x) `minusInt` (I# y) = I# (x -# y)
818 (I# x) `timesInt` (I# y) = I# (x *# y)
819 (I# x) `quotInt` (I# y) = I# (x `quotInt#` y)
820 (I# x) `remInt` (I# y) = I# (x `remInt#` y)
821 (I# x) `divInt` (I# y) = I# (x `divInt#` y)
822 (I# x) `modInt` (I# y) = I# (x `modInt#` y)
825 "x# +# 0#" forall x#. x# +# 0# = x#
826 "0# +# x#" forall x#. 0# +# x# = x#
827 "x# -# 0#" forall x#. x# -# 0# = x#
828 "x# -# x#" forall x#. x# -# x# = 0#
829 "x# *# 0#" forall x#. x# *# 0# = 0#
830 "0# *# x#" forall x#. 0# *# x# = 0#
831 "x# *# 1#" forall x#. x# *# 1# = x#
832 "1# *# x#" forall x#. 1# *# x# = x#
835 gcdInt (I# a) (I# b) = g a b
836 where g 0# 0# = error "GHC.Base.gcdInt: gcd 0 0 is undefined"
839 g _ _ = I# (gcdInt# absA absB)
841 absInt x = if x <# 0# then negateInt# x else x
846 negateInt :: Int -> Int
847 negateInt (I# x) = I# (negateInt# x)
849 gtInt, geInt, eqInt, neInt, ltInt, leInt :: Int -> Int -> Bool
850 (I# x) `gtInt` (I# y) = x ># y
851 (I# x) `geInt` (I# y) = x >=# y
852 (I# x) `eqInt` (I# y) = x ==# y
853 (I# x) `neInt` (I# y) = x /=# y
854 (I# x) `ltInt` (I# y) = x <# y
855 (I# x) `leInt` (I# y) = x <=# y
858 "x# ># x#" forall x#. x# ># x# = False
859 "x# >=# x#" forall x#. x# >=# x# = True
860 "x# ==# x#" forall x#. x# ==# x# = True
861 "x# /=# x#" forall x#. x# /=# x# = False
862 "x# <# x#" forall x#. x# <# x# = False
863 "x# <=# x#" forall x#. x# <=# x# = True
867 "plusFloat x 0.0" forall x#. plusFloat# x# 0.0# = x#
868 "plusFloat 0.0 x" forall x#. plusFloat# 0.0# x# = x#
869 "minusFloat x 0.0" forall x#. minusFloat# x# 0.0# = x#
870 "minusFloat x x" forall x#. minusFloat# x# x# = 0.0#
871 "timesFloat x 0.0" forall x#. timesFloat# x# 0.0# = 0.0#
872 "timesFloat0.0 x" forall x#. timesFloat# 0.0# x# = 0.0#
873 "timesFloat x 1.0" forall x#. timesFloat# x# 1.0# = x#
874 "timesFloat 1.0 x" forall x#. timesFloat# 1.0# x# = x#
875 "divideFloat x 1.0" forall x#. divideFloat# x# 1.0# = x#
879 "plusDouble x 0.0" forall x#. (+##) x# 0.0## = x#
880 "plusDouble 0.0 x" forall x#. (+##) 0.0## x# = x#
881 "minusDouble x 0.0" forall x#. (-##) x# 0.0## = x#
882 "minusDouble x x" forall x#. (-##) x# x# = 0.0##
883 "timesDouble x 0.0" forall x#. (*##) x# 0.0## = 0.0##
884 "timesDouble 0.0 x" forall x#. (*##) 0.0## x# = 0.0##
885 "timesDouble x 1.0" forall x#. (*##) x# 1.0## = x#
886 "timesDouble 1.0 x" forall x#. (*##) 1.0## x# = x#
887 "divideDouble x 1.0" forall x#. (/##) x# 1.0## = x#
890 -- Wrappers for the shift operations. The uncheckedShift# family are
891 -- undefined when the amount being shifted by is greater than the size
892 -- in bits of Int#, so these wrappers perform a check and return
893 -- either zero or -1 appropriately.
895 -- Note that these wrappers still produce undefined results when the
896 -- second argument (the shift amount) is negative.
898 -- | Shift the argument left by the specified number of bits
899 -- (which must be non-negative).
900 shiftL# :: Word# -> Int# -> Word#
901 a `shiftL#` b | b >=# WORD_SIZE_IN_BITS# = int2Word# 0#
902 | otherwise = a `uncheckedShiftL#` b
904 -- | Shift the argument right by the specified number of bits
905 -- (which must be non-negative).
906 shiftRL# :: Word# -> Int# -> Word#
907 a `shiftRL#` b | b >=# WORD_SIZE_IN_BITS# = int2Word# 0#
908 | otherwise = a `uncheckedShiftRL#` b
910 -- | Shift the argument left by the specified number of bits
911 -- (which must be non-negative).
912 iShiftL# :: Int# -> Int# -> Int#
913 a `iShiftL#` b | b >=# WORD_SIZE_IN_BITS# = 0#
914 | otherwise = a `uncheckedIShiftL#` b
916 -- | Shift the argument right (signed) by the specified number of bits
917 -- (which must be non-negative).
918 iShiftRA# :: Int# -> Int# -> Int#
919 a `iShiftRA#` b | b >=# WORD_SIZE_IN_BITS# = if a <# 0# then (-1#) else 0#
920 | otherwise = a `uncheckedIShiftRA#` b
922 -- | Shift the argument right (unsigned) by the specified number of bits
923 -- (which must be non-negative).
924 iShiftRL# :: Int# -> Int# -> Int#
925 a `iShiftRL#` b | b >=# WORD_SIZE_IN_BITS# = 0#
926 | otherwise = a `uncheckedIShiftRL#` b
928 #if WORD_SIZE_IN_BITS == 32
930 "narrow32Int#" forall x#. narrow32Int# x# = x#
931 "narrow32Word#" forall x#. narrow32Word# x# = x#
936 "int2Word2Int" forall x#. int2Word# (word2Int# x#) = x#
937 "word2Int2Word" forall x#. word2Int# (int2Word# x#) = x#
942 %********************************************************
944 \subsection{Unpacking C strings}
946 %********************************************************
948 This code is needed for virtually all programs, since it's used for
949 unpacking the strings of error messages.
952 unpackCString# :: Addr# -> [Char]
953 {-# NOINLINE [1] unpackCString# #-}
958 | ch `eqChar#` '\0'# = []
959 | otherwise = C# ch : unpack (nh +# 1#)
961 ch = indexCharOffAddr# addr nh
963 unpackAppendCString# :: Addr# -> [Char] -> [Char]
964 unpackAppendCString# addr rest
968 | ch `eqChar#` '\0'# = rest
969 | otherwise = C# ch : unpack (nh +# 1#)
971 ch = indexCharOffAddr# addr nh
973 unpackFoldrCString# :: Addr# -> (Char -> a -> a) -> a -> a
974 {-# NOINLINE [0] unpackFoldrCString# #-}
975 -- Don't inline till right at the end;
976 -- usually the unpack-list rule turns it into unpackCStringList
977 unpackFoldrCString# addr f z
981 | ch `eqChar#` '\0'# = z
982 | otherwise = C# ch `f` unpack (nh +# 1#)
984 ch = indexCharOffAddr# addr nh
986 unpackCStringUtf8# :: Addr# -> [Char]
987 unpackCStringUtf8# addr
991 | ch `eqChar#` '\0'# = []
992 | ch `leChar#` '\x7F'# = C# ch : unpack (nh +# 1#)
993 | ch `leChar#` '\xDF'# =
994 C# (chr# (((ord# ch -# 0xC0#) `uncheckedIShiftL#` 6#) +#
995 (ord# (indexCharOffAddr# addr (nh +# 1#)) -# 0x80#))) :
997 | ch `leChar#` '\xEF'# =
998 C# (chr# (((ord# ch -# 0xE0#) `uncheckedIShiftL#` 12#) +#
999 ((ord# (indexCharOffAddr# addr (nh +# 1#)) -# 0x80#) `uncheckedIShiftL#` 6#) +#
1000 (ord# (indexCharOffAddr# addr (nh +# 2#)) -# 0x80#))) :
1003 C# (chr# (((ord# ch -# 0xF0#) `uncheckedIShiftL#` 18#) +#
1004 ((ord# (indexCharOffAddr# addr (nh +# 1#)) -# 0x80#) `uncheckedIShiftL#` 12#) +#
1005 ((ord# (indexCharOffAddr# addr (nh +# 2#)) -# 0x80#) `uncheckedIShiftL#` 6#) +#
1006 (ord# (indexCharOffAddr# addr (nh +# 3#)) -# 0x80#))) :
1009 ch = indexCharOffAddr# addr nh
1011 unpackNBytes# :: Addr# -> Int# -> [Char]
1012 unpackNBytes# _addr 0# = []
1013 unpackNBytes# addr len# = unpack [] (len# -# 1#)
1018 case indexCharOffAddr# addr i# of
1019 ch -> unpack (C# ch : acc) (i# -# 1#)
1022 "unpack" [~1] forall a . unpackCString# a = build (unpackFoldrCString# a)
1023 "unpack-list" [1] forall a . unpackFoldrCString# a (:) [] = unpackCString# a
1024 "unpack-append" forall a n . unpackFoldrCString# a (:) n = unpackAppendCString# a n
1026 -- There's a built-in rule (in PrelRules.lhs) for
1027 -- unpackFoldr "foo" c (unpackFoldr "baz" c n) = unpackFoldr "foobaz" c n
1034 -- | A special argument for the 'Control.Monad.ST.ST' type constructor,
1035 -- indexing a state embedded in the 'Prelude.IO' monad by
1036 -- 'Control.Monad.ST.stToIO'.