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.Tuple 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.List List functions
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 GHC.ST The ST monad, instances and a few helper functions
48 Ix Classes: Ix, plus instances for Int, Bool, Char, Integer, Ordering, tuples
50 GHC.Arr Types: Array, MutableArray, MutableVar
52 Arrays are used by a function in GHC.Float
54 GHC.Float Classes: Floating, RealFloat
55 Types: Float, Double, plus instances of all classes so far
57 This module contains everything to do with floating point.
58 It is a big module (900 lines)
59 With a bit of luck, many modules can be compiled without ever reading GHC.Float.hi
62 Other Prelude modules are much easier with fewer complex dependencies.
65 {-# OPTIONS_GHC -fno-implicit-prelude #-}
66 -----------------------------------------------------------------------------
69 -- Copyright : (c) The University of Glasgow, 1992-2002
70 -- License : see libraries/base/LICENSE
72 -- Maintainer : cvs-ghc@haskell.org
73 -- Stability : internal
74 -- Portability : non-portable (GHC extensions)
76 -- Basic data types and classes.
78 -----------------------------------------------------------------------------
86 module GHC.Prim, -- Re-export GHC.Prim and GHC.Err, to avoid lots
87 module GHC.Err -- of people having to import it explicitly
92 import {-# SOURCE #-} GHC.Err
96 infix 4 ==, /=, <, <=, >=, >
102 default () -- Double isn't available yet
106 %*********************************************************
108 \subsection{DEBUGGING STUFF}
109 %* (for use when compiling GHC.Base itself doesn't work)
111 %*********************************************************
115 data Bool = False | True
116 data Ordering = LT | EQ | GT
124 (&&) True True = True
130 unpackCString# :: Addr# -> [Char]
131 unpackFoldrCString# :: Addr# -> (Char -> a -> a) -> a -> a
132 unpackAppendCString# :: Addr# -> [Char] -> [Char]
133 unpackCStringUtf8# :: Addr# -> [Char]
134 unpackCString# a = error "urk"
135 unpackFoldrCString# a = error "urk"
136 unpackAppendCString# a = error "urk"
137 unpackCStringUtf8# a = error "urk"
142 %*********************************************************
144 \subsection{Standard classes @Eq@, @Ord@}
146 %*********************************************************
150 -- | The 'Eq' class defines equality ('==') and inequality ('/=').
151 -- All the basic datatypes exported by the "Prelude" are instances of 'Eq',
152 -- and 'Eq' may be derived for any datatype whose constituents are also
153 -- instances of 'Eq'.
155 -- Minimal complete definition: either '==' or '/='.
158 (==), (/=) :: a -> a -> Bool
160 x /= y = not (x == y)
161 x == y = not (x /= y)
163 -- | The 'Ord' class is used for totally ordered datatypes.
165 -- Instances of 'Ord' can be derived for any user-defined
166 -- datatype whose constituent types are in 'Ord'. The declared order
167 -- of the constructors in the data declaration determines the ordering
168 -- in derived 'Ord' instances. The 'Ordering' datatype allows a single
169 -- comparison to determine the precise ordering of two objects.
171 -- Minimal complete definition: either 'compare' or '<='.
172 -- Using 'compare' can be more efficient for complex types.
174 class (Eq a) => Ord a where
175 compare :: a -> a -> Ordering
176 (<), (<=), (>), (>=) :: a -> a -> Bool
177 max, min :: a -> a -> a
181 | x <= y = LT -- NB: must be '<=' not '<' to validate the
182 -- above claim about the minimal things that
183 -- can be defined for an instance of Ord
186 x < y = case compare x y of { LT -> True; _other -> False }
187 x <= y = case compare x y of { GT -> False; _other -> True }
188 x > y = case compare x y of { GT -> True; _other -> False }
189 x >= y = case compare x y of { LT -> False; _other -> True }
191 -- These two default methods use '<=' rather than 'compare'
192 -- because the latter is often more expensive
193 max x y = if x <= y then y else x
194 min x y = if x <= y then x else y
197 %*********************************************************
199 \subsection{Monadic classes @Functor@, @Monad@ }
201 %*********************************************************
204 {- | The 'Functor' class is used for types that can be mapped over.
205 Instances of 'Functor' should satisfy the following laws:
208 > fmap (f . g) == fmap f . fmap g
210 The instances of 'Functor' for lists, 'Data.Maybe.Maybe' and 'System.IO.IO'
211 defined in the "Prelude" satisfy these laws.
214 class Functor f where
215 fmap :: (a -> b) -> f a -> f b
217 {- | The 'Monad' class defines the basic operations over a /monad/,
218 a concept from a branch of mathematics known as /category theory/.
219 From the perspective of a Haskell programmer, however, it is best to
220 think of a monad as an /abstract datatype/ of actions.
221 Haskell's @do@ expressions provide a convenient syntax for writing
224 Minimal complete definition: '>>=' and 'return'.
226 Instances of 'Monad' should satisfy the following laws:
228 > return a >>= k == k a
230 > m >>= (\x -> k x >>= h) == (m >>= k) >>= h
232 Instances of both 'Monad' and 'Functor' should additionally satisfy the law:
234 > fmap f xs == xs >>= return . f
236 The instances of 'Monad' for lists, 'Data.Maybe.Maybe' and 'System.IO.IO'
237 defined in the "Prelude" satisfy these laws.
241 -- | Sequentially compose two actions, passing any value produced
242 -- by the first as an argument to the second.
243 (>>=) :: forall a b. m a -> (a -> m b) -> m b
244 -- | Sequentially compose two actions, discarding any value produced
245 -- by the first, like sequencing operators (such as the semicolon)
246 -- in imperative languages.
247 (>>) :: forall a b. m a -> m b -> m b
248 -- Explicit for-alls so that we know what order to
249 -- give type arguments when desugaring
251 -- | Inject a value into the monadic type.
253 -- | Fail with a message. This operation is not part of the
254 -- mathematical definition of a monad, but is invoked on pattern-match
255 -- failure in a @do@ expression.
256 fail :: String -> m a
258 m >> k = m >>= \_ -> k
263 %*********************************************************
265 \subsection{The list type}
267 %*********************************************************
270 data [] a = [] | a : [a] -- do explicitly: deriving (Eq, Ord)
271 -- to avoid weird names like con2tag_[]#
274 instance (Eq a) => Eq [a] where
275 {-# SPECIALISE instance Eq [Char] #-}
277 (x:xs) == (y:ys) = x == y && xs == ys
280 instance (Ord a) => Ord [a] where
281 {-# SPECIALISE instance Ord [Char] #-}
283 compare [] (_:_) = LT
284 compare (_:_) [] = GT
285 compare (x:xs) (y:ys) = case compare x y of
289 instance Functor [] where
292 instance Monad [] where
293 m >>= k = foldr ((++) . k) [] m
294 m >> k = foldr ((++) . (\ _ -> k)) [] m
299 A few list functions that appear here because they are used here.
300 The rest of the prelude list functions are in GHC.List.
302 ----------------------------------------------
303 -- foldr/build/augment
304 ----------------------------------------------
307 -- | 'foldr', applied to a binary operator, a starting value (typically
308 -- the right-identity of the operator), and a list, reduces the list
309 -- using the binary operator, from right to left:
311 -- > foldr f z [x1, x2, ..., xn] == x1 `f` (x2 `f` ... (xn `f` z)...)
313 foldr :: (a -> b -> b) -> b -> [a] -> b
315 -- foldr f z (x:xs) = f x (foldr f z xs)
316 {-# INLINE [0] foldr #-}
317 -- Inline only in the final stage, after the foldr/cons rule has had a chance
321 go (y:ys) = y `k` go ys
323 -- | A list producer that can be fused with 'foldr'.
324 -- This function is merely
326 -- > build g = g (:) []
328 -- but GHC's simplifier will transform an expression of the form
329 -- @'foldr' k z ('build' g)@, which may arise after inlining, to @g k z@,
330 -- which avoids producing an intermediate list.
332 build :: forall a. (forall b. (a -> b -> b) -> b -> b) -> [a]
333 {-# INLINE [1] build #-}
334 -- The INLINE is important, even though build is tiny,
335 -- because it prevents [] getting inlined in the version that
336 -- appears in the interface file. If [] *is* inlined, it
337 -- won't match with [] appearing in rules in an importing module.
339 -- The "1" says to inline in phase 1
343 -- | A list producer that can be fused with 'foldr'.
344 -- This function is merely
346 -- > augment g xs = g (:) xs
348 -- but GHC's simplifier will transform an expression of the form
349 -- @'foldr' k z ('augment' g xs)@, which may arise after inlining, to
350 -- @g k ('foldr' k z xs)@, which avoids producing an intermediate list.
352 augment :: forall a. (forall b. (a->b->b) -> b -> b) -> [a] -> [a]
353 {-# INLINE [1] augment #-}
354 augment g xs = g (:) xs
357 "fold/build" forall k z (g::forall b. (a->b->b) -> b -> b) .
358 foldr k z (build g) = g k z
360 "foldr/augment" forall k z xs (g::forall b. (a->b->b) -> b -> b) .
361 foldr k z (augment g xs) = g k (foldr k z xs)
363 "foldr/id" foldr (:) [] = \x -> x
364 "foldr/app" [1] forall ys. foldr (:) ys = \xs -> xs ++ ys
365 -- Only activate this from phase 1, because that's
366 -- when we disable the rule that expands (++) into foldr
368 -- The foldr/cons rule looks nice, but it can give disastrously
369 -- bloated code when commpiling
370 -- array (a,b) [(1,2), (2,2), (3,2), ...very long list... ]
371 -- i.e. when there are very very long literal lists
372 -- So I've disabled it for now. We could have special cases
373 -- for short lists, I suppose.
374 -- "foldr/cons" forall k z x xs. foldr k z (x:xs) = k x (foldr k z xs)
376 "foldr/single" forall k z x. foldr k z [x] = k x z
377 "foldr/nil" forall k z. foldr k z [] = z
379 "augment/build" forall (g::forall b. (a->b->b) -> b -> b)
380 (h::forall b. (a->b->b) -> b -> b) .
381 augment g (build h) = build (\c n -> g c (h c n))
382 "augment/nil" forall (g::forall b. (a->b->b) -> b -> b) .
383 augment g [] = build g
386 -- This rule is true, but not (I think) useful:
387 -- augment g (augment h t) = augment (\cn -> g c (h c n)) t
391 ----------------------------------------------
393 ----------------------------------------------
396 -- | 'map' @f xs@ is the list obtained by applying @f@ to each element
399 -- > map f [x1, x2, ..., xn] == [f x1, f x2, ..., f xn]
400 -- > map f [x1, x2, ...] == [f x1, f x2, ...]
402 map :: (a -> b) -> [a] -> [b]
404 map f (x:xs) = f x : map f xs
407 mapFB :: (elt -> lst -> lst) -> (a -> elt) -> a -> lst -> lst
408 {-# INLINE [0] mapFB #-}
409 mapFB c f x ys = c (f x) ys
411 -- The rules for map work like this.
413 -- Up to (but not including) phase 1, we use the "map" rule to
414 -- rewrite all saturated applications of map with its build/fold
415 -- form, hoping for fusion to happen.
416 -- In phase 1 and 0, we switch off that rule, inline build, and
417 -- switch on the "mapList" rule, which rewrites the foldr/mapFB
418 -- thing back into plain map.
420 -- It's important that these two rules aren't both active at once
421 -- (along with build's unfolding) else we'd get an infinite loop
422 -- in the rules. Hence the activation control below.
424 -- The "mapFB" rule optimises compositions of map.
426 -- This same pattern is followed by many other functions:
427 -- e.g. append, filter, iterate, repeat, etc.
430 "map" [~1] forall f xs. map f xs = build (\c n -> foldr (mapFB c f) n xs)
431 "mapList" [1] forall f. foldr (mapFB (:) f) [] = map f
432 "mapFB" forall c f g. mapFB (mapFB c f) g = mapFB c (f.g)
437 ----------------------------------------------
439 ----------------------------------------------
441 -- | Append two lists, i.e.,
443 -- > [x1, ..., xm] ++ [y1, ..., yn] == [x1, ..., xm, y1, ..., yn]
444 -- > [x1, ..., xm] ++ [y1, ...] == [x1, ..., xm, y1, ...]
446 -- If the first list is not finite, the result is the first list.
448 (++) :: [a] -> [a] -> [a]
450 (++) (x:xs) ys = x : xs ++ ys
453 "++" [~1] forall xs ys. xs ++ ys = augment (\c n -> foldr c n xs) ys
459 %*********************************************************
461 \subsection{Type @Bool@}
463 %*********************************************************
466 -- |The 'Bool' type is an enumeration. It is defined with 'False'
467 -- first so that the corresponding 'Prelude.Enum' instance will give
468 -- 'Prelude.fromEnum' 'False' the value zero, and
469 -- 'Prelude.fromEnum' 'True' the value 1.
470 data Bool = False | True deriving (Eq, Ord)
471 -- Read in GHC.Read, Show in GHC.Show
476 (&&) :: Bool -> Bool -> Bool
481 (||) :: Bool -> Bool -> Bool
490 -- |'otherwise' is defined as the value 'True'. It helps to make
491 -- guards more readable. eg.
493 -- > f x | x < 0 = ...
494 -- > | otherwise = ...
500 %*********************************************************
502 \subsection{The @()@ type}
504 %*********************************************************
506 The Unit type is here because virtually any program needs it (whereas
507 some programs may get away without consulting GHC.Tup). Furthermore,
508 the renamer currently *always* asks for () to be in scope, so that
509 ccalls can use () as their default type; so when compiling GHC.Base we
510 need (). (We could arrange suck in () only if -fglasgow-exts, but putting
511 it here seems more direct.)
514 -- | The unit datatype @()@ has one non-undefined member, the nullary
522 instance Ord () where
533 %*********************************************************
535 \subsection{Type @Ordering@}
537 %*********************************************************
540 -- | Represents an ordering relationship between two values: less
541 -- than, equal to, or greater than. An 'Ordering' is returned by
543 data Ordering = LT | EQ | GT deriving (Eq, Ord)
544 -- Read in GHC.Read, Show in GHC.Show
548 %*********************************************************
550 \subsection{Type @Char@ and @String@}
552 %*********************************************************
555 -- | A 'String' is a list of characters. String constants in Haskell are values
560 {-| The character type 'Char' is an enumeration whose values represent
561 Unicode (or equivalently ISO\/IEC 10646) characters
562 (see <http://www.unicode.org/> for details).
563 This set extends the ISO 8859-1 (Latin-1) character set
564 (the first 256 charachers), which is itself an extension of the ASCII
565 character set (the first 128 characters).
566 A character literal in Haskell has type 'Char'.
568 To convert a 'Char' to or from the corresponding 'Int' value defined
569 by Unicode, use 'Prelude.toEnum' and 'Prelude.fromEnum' from the
570 'Prelude.Enum' class respectively (or equivalently 'ord' and 'chr').
574 -- We don't use deriving for Eq and Ord, because for Ord the derived
575 -- instance defines only compare, which takes two primops. Then
576 -- '>' uses compare, and therefore takes two primops instead of one.
578 instance Eq Char where
579 (C# c1) == (C# c2) = c1 `eqChar#` c2
580 (C# c1) /= (C# c2) = c1 `neChar#` c2
582 instance Ord Char where
583 (C# c1) > (C# c2) = c1 `gtChar#` c2
584 (C# c1) >= (C# c2) = c1 `geChar#` c2
585 (C# c1) <= (C# c2) = c1 `leChar#` c2
586 (C# c1) < (C# c2) = c1 `ltChar#` c2
589 "x# `eqChar#` x#" forall x#. x# `eqChar#` x# = True
590 "x# `neChar#` x#" forall x#. x# `neChar#` x# = False
591 "x# `gtChar#` x#" forall x#. x# `gtChar#` x# = False
592 "x# `geChar#` x#" forall x#. x# `geChar#` x# = True
593 "x# `leChar#` x#" forall x#. x# `leChar#` x# = True
594 "x# `ltChar#` x#" forall x#. x# `ltChar#` x# = False
597 -- | The 'Prelude.toEnum' method restricted to the type 'Data.Char.Char'.
599 chr (I# i#) | int2Word# i# `leWord#` int2Word# 0x10FFFF# = C# (chr# i#)
600 | otherwise = error "Prelude.chr: bad argument"
602 unsafeChr :: Int -> Char
603 unsafeChr (I# i#) = C# (chr# i#)
605 -- | The 'Prelude.fromEnum' method restricted to the type 'Data.Char.Char'.
607 ord (C# c#) = I# (ord# c#)
610 String equality is used when desugaring pattern-matches against strings.
613 eqString :: String -> String -> Bool
614 eqString [] [] = True
615 eqString (c1:cs1) (c2:cs2) = c1 == c2 && cs1 `eqString` cs2
616 eqString cs1 cs2 = False
618 {-# RULES "eqString" (==) = eqString #-}
619 -- eqString also has a BuiltInRule in PrelRules.lhs:
620 -- eqString (unpackCString# (Lit s1)) (unpackCString# (Lit s2) = s1==s2
624 %*********************************************************
626 \subsection{Type @Int@}
628 %*********************************************************
632 -- ^A fixed-precision integer type with at least the range @[-2^29 .. 2^29-1]@.
633 -- The exact range for a given implementation can be determined by using
634 -- 'Prelude.minBound' and 'Prelude.maxBound' from the 'Prelude.Bounded' class.
636 zeroInt, oneInt, twoInt, maxInt, minInt :: Int
641 {- Seems clumsy. Should perhaps put minInt and MaxInt directly into MachDeps.h -}
642 #if WORD_SIZE_IN_BITS == 31
643 minInt = I# (-0x40000000#)
644 maxInt = I# 0x3FFFFFFF#
645 #elif WORD_SIZE_IN_BITS == 32
646 minInt = I# (-0x80000000#)
647 maxInt = I# 0x7FFFFFFF#
649 minInt = I# (-0x8000000000000000#)
650 maxInt = I# 0x7FFFFFFFFFFFFFFF#
653 instance Eq Int where
657 instance Ord Int where
664 compareInt :: Int -> Int -> Ordering
665 (I# x#) `compareInt` (I# y#) = compareInt# x# y#
667 compareInt# :: Int# -> Int# -> Ordering
675 %*********************************************************
677 \subsection{The function type}
679 %*********************************************************
682 -- | Identity function.
686 -- | The call '(lazy e)' means the same as 'e', but 'lazy' has a
687 -- magical strictness property: it is lazy in its first argument,
688 -- even though its semantics is strict.
691 -- Implementation note: its strictness and unfolding are over-ridden
692 -- by the definition in MkId.lhs; in both cases to nothing at all.
693 -- That way, 'lazy' does not get inlined, and the strictness analyser
694 -- sees it as lazy. Then the worker/wrapper phase inlines it.
698 -- | The call '(inline f)' reduces to 'f', but 'inline' has a BuiltInRule
699 -- that tries to inline 'f' (if it has an unfolding) unconditionally
700 -- The 'NOINLINE' pragma arranges that inline only gets inlined (and
701 -- hence eliminated) late in compilation, after the rule has had
702 -- a god chance to fire.
704 {-# NOINLINE[0] inline #-}
707 -- Assertion function. This simply ignores its boolean argument.
708 -- The compiler may rewrite it to @('assertError' line)@.
710 -- | If the first argument evaluates to 'True', then the result is the
711 -- second argument. Otherwise an 'AssertionFailed' exception is raised,
712 -- containing a 'String' with the source file and line number of the
715 -- Assertions can normally be turned on or off with a compiler flag
716 -- (for GHC, assertions are normally on unless optimisation is turned on
717 -- with @-O@ or the @-fignore-asserts@
718 -- option is given). When assertions are turned off, the first
719 -- argument to 'assert' is ignored, and the second argument is
720 -- returned as the result.
722 -- SLPJ: in 5.04 etc 'assert' is in GHC.Prim,
723 -- but from Template Haskell onwards it's simply
724 -- defined here in Base.lhs
725 assert :: Bool -> a -> a
731 breakpointCond :: Bool -> a -> a
732 breakpointCond _ r = r
734 -- | Constant function.
738 -- | Function composition.
740 (.) :: (b -> c) -> (a -> b) -> a -> c
743 -- | @'flip' f@ takes its (first) two arguments in the reverse order of @f@.
744 flip :: (a -> b -> c) -> b -> a -> c
747 -- | Application operator. This operator is redundant, since ordinary
748 -- application @(f x)@ means the same as @(f '$' x)@. However, '$' has
749 -- low, right-associative binding precedence, so it sometimes allows
750 -- parentheses to be omitted; for example:
752 -- > f $ g $ h x = f (g (h x))
754 -- It is also useful in higher-order situations, such as @'map' ('$' 0) xs@,
755 -- or @'Data.List.zipWith' ('$') fs xs@.
757 ($) :: (a -> b) -> a -> b
760 -- | @'until' p f@ yields the result of applying @f@ until @p@ holds.
761 until :: (a -> Bool) -> (a -> a) -> a -> a
762 until p f x | p x = x
763 | otherwise = until p f (f x)
765 -- | 'asTypeOf' is a type-restricted version of 'const'. It is usually
766 -- used as an infix operator, and its typing forces its first argument
767 -- (which is usually overloaded) to have the same type as the second.
768 asTypeOf :: a -> a -> a
772 %*********************************************************
774 \subsection{Generics}
776 %*********************************************************
781 data (:+:) a b = Inl a | Inr b
782 data (:*:) a b = a :*: b
786 %*********************************************************
788 \subsection{@getTag@}
790 %*********************************************************
792 Returns the 'tag' of a constructor application; this function is used
793 by the deriving code for Eq, Ord and Enum.
795 The primitive dataToTag# requires an evaluated constructor application
796 as its argument, so we provide getTag as a wrapper that performs the
797 evaluation before calling dataToTag#. We could have dataToTag#
798 evaluate its argument, but we prefer to do it this way because (a)
799 dataToTag# can be an inline primop if it doesn't need to do any
800 evaluation, and (b) we want to expose the evaluation to the
801 simplifier, because it might be possible to eliminate the evaluation
802 in the case when the argument is already known to be evaluated.
805 {-# INLINE getTag #-}
807 getTag x = x `seq` dataToTag# x
810 %*********************************************************
812 \subsection{Numeric primops}
814 %*********************************************************
817 divInt# :: Int# -> Int# -> Int#
819 -- Be careful NOT to overflow if we do any additional arithmetic
820 -- on the arguments... the following previous version of this
821 -- code has problems with overflow:
822 -- | (x# ># 0#) && (y# <# 0#) = ((x# -# y#) -# 1#) `quotInt#` y#
823 -- | (x# <# 0#) && (y# ># 0#) = ((x# -# y#) +# 1#) `quotInt#` y#
824 | (x# ># 0#) && (y# <# 0#) = ((x# -# 1#) `quotInt#` y#) -# 1#
825 | (x# <# 0#) && (y# ># 0#) = ((x# +# 1#) `quotInt#` y#) -# 1#
826 | otherwise = x# `quotInt#` y#
828 modInt# :: Int# -> Int# -> Int#
830 | (x# ># 0#) && (y# <# 0#) ||
831 (x# <# 0#) && (y# ># 0#) = if r# /=# 0# then r# +# y# else 0#
837 Definitions of the boxed PrimOps; these will be
838 used in the case of partial applications, etc.
847 {-# INLINE plusInt #-}
848 {-# INLINE minusInt #-}
849 {-# INLINE timesInt #-}
850 {-# INLINE quotInt #-}
851 {-# INLINE remInt #-}
852 {-# INLINE negateInt #-}
854 plusInt, minusInt, timesInt, quotInt, remInt, divInt, modInt, gcdInt :: Int -> Int -> Int
855 (I# x) `plusInt` (I# y) = I# (x +# y)
856 (I# x) `minusInt` (I# y) = I# (x -# y)
857 (I# x) `timesInt` (I# y) = I# (x *# y)
858 (I# x) `quotInt` (I# y) = I# (x `quotInt#` y)
859 (I# x) `remInt` (I# y) = I# (x `remInt#` y)
860 (I# x) `divInt` (I# y) = I# (x `divInt#` y)
861 (I# x) `modInt` (I# y) = I# (x `modInt#` y)
864 "x# +# 0#" forall x#. x# +# 0# = x#
865 "0# +# x#" forall x#. 0# +# x# = x#
866 "x# -# 0#" forall x#. x# -# 0# = x#
867 "x# -# x#" forall x#. x# -# x# = 0#
868 "x# *# 0#" forall x#. x# *# 0# = 0#
869 "0# *# x#" forall x#. 0# *# x# = 0#
870 "x# *# 1#" forall x#. x# *# 1# = x#
871 "1# *# x#" forall x#. 1# *# x# = x#
874 gcdInt (I# a) (I# b) = g a b
875 where g 0# 0# = error "GHC.Base.gcdInt: gcd 0 0 is undefined"
878 g _ _ = I# (gcdInt# absA absB)
880 absInt x = if x <# 0# then negateInt# x else x
885 negateInt :: Int -> Int
886 negateInt (I# x) = I# (negateInt# x)
888 gtInt, geInt, eqInt, neInt, ltInt, leInt :: Int -> Int -> Bool
889 (I# x) `gtInt` (I# y) = x ># y
890 (I# x) `geInt` (I# y) = x >=# y
891 (I# x) `eqInt` (I# y) = x ==# y
892 (I# x) `neInt` (I# y) = x /=# y
893 (I# x) `ltInt` (I# y) = x <# y
894 (I# x) `leInt` (I# y) = x <=# y
897 "x# ># x#" forall x#. x# ># x# = False
898 "x# >=# x#" forall x#. x# >=# x# = True
899 "x# ==# x#" forall x#. x# ==# x# = True
900 "x# /=# x#" forall x#. x# /=# x# = False
901 "x# <# x#" forall x#. x# <# x# = False
902 "x# <=# x#" forall x#. x# <=# x# = True
906 "plusFloat x 0.0" forall x#. plusFloat# x# 0.0# = x#
907 "plusFloat 0.0 x" forall x#. plusFloat# 0.0# x# = x#
908 "minusFloat x 0.0" forall x#. minusFloat# x# 0.0# = x#
909 "minusFloat x x" forall x#. minusFloat# x# x# = 0.0#
910 "timesFloat x 0.0" forall x#. timesFloat# x# 0.0# = 0.0#
911 "timesFloat0.0 x" forall x#. timesFloat# 0.0# x# = 0.0#
912 "timesFloat x 1.0" forall x#. timesFloat# x# 1.0# = x#
913 "timesFloat 1.0 x" forall x#. timesFloat# 1.0# x# = x#
914 "divideFloat x 1.0" forall x#. divideFloat# x# 1.0# = x#
918 "plusDouble x 0.0" forall x#. (+##) x# 0.0## = x#
919 "plusDouble 0.0 x" forall x#. (+##) 0.0## x# = x#
920 "minusDouble x 0.0" forall x#. (-##) x# 0.0## = x#
921 "minusDouble x x" forall x#. (-##) x# x# = 0.0##
922 "timesDouble x 0.0" forall x#. (*##) x# 0.0## = 0.0##
923 "timesDouble 0.0 x" forall x#. (*##) 0.0## x# = 0.0##
924 "timesDouble x 1.0" forall x#. (*##) x# 1.0## = x#
925 "timesDouble 1.0 x" forall x#. (*##) 1.0## x# = x#
926 "divideDouble x 1.0" forall x#. (/##) x# 1.0## = x#
929 -- Wrappers for the shift operations. The uncheckedShift# family are
930 -- undefined when the amount being shifted by is greater than the size
931 -- in bits of Int#, so these wrappers perform a check and return
932 -- either zero or -1 appropriately.
934 -- Note that these wrappers still produce undefined results when the
935 -- second argument (the shift amount) is negative.
937 -- | Shift the argument left by the specified number of bits
938 -- (which must be non-negative).
939 shiftL# :: Word# -> Int# -> Word#
940 a `shiftL#` b | b >=# WORD_SIZE_IN_BITS# = int2Word# 0#
941 | otherwise = a `uncheckedShiftL#` b
943 -- | Shift the argument right by the specified number of bits
944 -- (which must be non-negative).
945 shiftRL# :: Word# -> Int# -> Word#
946 a `shiftRL#` b | b >=# WORD_SIZE_IN_BITS# = int2Word# 0#
947 | otherwise = a `uncheckedShiftRL#` b
949 -- | Shift the argument left by the specified number of bits
950 -- (which must be non-negative).
951 iShiftL# :: Int# -> Int# -> Int#
952 a `iShiftL#` b | b >=# WORD_SIZE_IN_BITS# = 0#
953 | otherwise = a `uncheckedIShiftL#` b
955 -- | Shift the argument right (signed) by the specified number of bits
956 -- (which must be non-negative).
957 iShiftRA# :: Int# -> Int# -> Int#
958 a `iShiftRA#` b | b >=# WORD_SIZE_IN_BITS# = if a <# 0# then (-1#) else 0#
959 | otherwise = a `uncheckedIShiftRA#` b
961 -- | Shift the argument right (unsigned) by the specified number of bits
962 -- (which must be non-negative).
963 iShiftRL# :: Int# -> Int# -> Int#
964 a `iShiftRL#` b | b >=# WORD_SIZE_IN_BITS# = 0#
965 | otherwise = a `uncheckedIShiftRL#` b
967 #if WORD_SIZE_IN_BITS == 32
969 "narrow32Int#" forall x#. narrow32Int# x# = x#
970 "narrow32Word#" forall x#. narrow32Word# x# = x#
975 "int2Word2Int" forall x#. int2Word# (word2Int# x#) = x#
976 "word2Int2Word" forall x#. word2Int# (int2Word# x#) = x#
981 %********************************************************
983 \subsection{Unpacking C strings}
985 %********************************************************
987 This code is needed for virtually all programs, since it's used for
988 unpacking the strings of error messages.
991 unpackCString# :: Addr# -> [Char]
992 {-# NOINLINE [1] unpackCString# #-}
997 | ch `eqChar#` '\0'# = []
998 | otherwise = C# ch : unpack (nh +# 1#)
1000 ch = indexCharOffAddr# addr nh
1002 unpackAppendCString# :: Addr# -> [Char] -> [Char]
1003 unpackAppendCString# addr rest
1007 | ch `eqChar#` '\0'# = rest
1008 | otherwise = C# ch : unpack (nh +# 1#)
1010 ch = indexCharOffAddr# addr nh
1012 unpackFoldrCString# :: Addr# -> (Char -> a -> a) -> a -> a
1013 {-# NOINLINE [0] unpackFoldrCString# #-}
1014 -- Don't inline till right at the end;
1015 -- usually the unpack-list rule turns it into unpackCStringList
1016 -- It also has a BuiltInRule in PrelRules.lhs:
1017 -- unpackFoldrCString# "foo" c (unpackFoldrCString# "baz" c n)
1018 -- = unpackFoldrCString# "foobaz" c n
1019 unpackFoldrCString# addr f z
1023 | ch `eqChar#` '\0'# = z
1024 | otherwise = C# ch `f` unpack (nh +# 1#)
1026 ch = indexCharOffAddr# addr nh
1028 unpackCStringUtf8# :: Addr# -> [Char]
1029 unpackCStringUtf8# addr
1033 | ch `eqChar#` '\0'# = []
1034 | ch `leChar#` '\x7F'# = C# ch : unpack (nh +# 1#)
1035 | ch `leChar#` '\xDF'# =
1036 C# (chr# (((ord# ch -# 0xC0#) `uncheckedIShiftL#` 6#) +#
1037 (ord# (indexCharOffAddr# addr (nh +# 1#)) -# 0x80#))) :
1039 | ch `leChar#` '\xEF'# =
1040 C# (chr# (((ord# ch -# 0xE0#) `uncheckedIShiftL#` 12#) +#
1041 ((ord# (indexCharOffAddr# addr (nh +# 1#)) -# 0x80#) `uncheckedIShiftL#` 6#) +#
1042 (ord# (indexCharOffAddr# addr (nh +# 2#)) -# 0x80#))) :
1045 C# (chr# (((ord# ch -# 0xF0#) `uncheckedIShiftL#` 18#) +#
1046 ((ord# (indexCharOffAddr# addr (nh +# 1#)) -# 0x80#) `uncheckedIShiftL#` 12#) +#
1047 ((ord# (indexCharOffAddr# addr (nh +# 2#)) -# 0x80#) `uncheckedIShiftL#` 6#) +#
1048 (ord# (indexCharOffAddr# addr (nh +# 3#)) -# 0x80#))) :
1051 ch = indexCharOffAddr# addr nh
1053 unpackNBytes# :: Addr# -> Int# -> [Char]
1054 unpackNBytes# _addr 0# = []
1055 unpackNBytes# addr len# = unpack [] (len# -# 1#)
1060 case indexCharOffAddr# addr i# of
1061 ch -> unpack (C# ch : acc) (i# -# 1#)
1064 "unpack" [~1] forall a . unpackCString# a = build (unpackFoldrCString# a)
1065 "unpack-list" [1] forall a . unpackFoldrCString# a (:) [] = unpackCString# a
1066 "unpack-append" forall a n . unpackFoldrCString# a (:) n = unpackAppendCString# a n
1068 -- There's a built-in rule (in PrelRules.lhs) for
1069 -- unpackFoldr "foo" c (unpackFoldr "baz" c n) = unpackFoldr "foobaz" c n
1076 -- | A special argument for the 'Control.Monad.ST.ST' type constructor,
1077 -- indexing a state embedded in the 'Prelude.IO' monad by
1078 -- 'Control.Monad.ST.stToIO'.