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, 'Data.Maybe.Maybe' and 'System.IO.IO'
213 defined in the "Prelude" satisfy these laws.
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 a concept from a branch of mathematics known as /category theory/.
221 From the perspective of a Haskell programmer, however, it is best to
222 think of a monad as an /abstract datatype/ of actions.
223 Haskell's @do@ expressions provide a convenient syntax for writing
226 Minimal complete definition: '>>=' and 'return'.
228 Instances of 'Monad' should satisfy the following laws:
230 > return a >>= k == k a
232 > m >>= (\x -> k x >>= h) == (m >>= k) >>= h
234 Instances of both 'Monad' and 'Functor' should additionally satisfy the law:
236 > fmap f xs == xs >>= return . f
238 The instances of 'Monad' for lists, 'Data.Maybe.Maybe' and 'System.IO.IO'
239 defined in the "Prelude" satisfy these laws.
243 -- | Sequentially compose two actions, passing any value produced
244 -- by the first as an argument to the second.
245 (>>=) :: forall a b. m a -> (a -> m b) -> m b
246 -- | Sequentially compose two actions, discarding any value produced
247 -- by the first, like sequencing operators (such as the semicolon)
248 -- in imperative languages.
249 (>>) :: forall a b. m a -> m b -> m b
250 -- Explicit for-alls so that we know what order to
251 -- give type arguments when desugaring
253 -- | Inject a value into the monadic type.
255 -- | Fail with a message. This operation is not part of the
256 -- mathematical definition of a monad, but is invoked on pattern-match
257 -- failure in a @do@ expression.
258 fail :: String -> m a
260 m >> k = m >>= \_ -> k
265 %*********************************************************
267 \subsection{The list type}
269 %*********************************************************
272 data [] a = [] | a : [a] -- do explicitly: deriving (Eq, Ord)
273 -- to avoid weird names like con2tag_[]#
276 instance (Eq a) => Eq [a] where
277 {-# SPECIALISE instance Eq [Char] #-}
279 (x:xs) == (y:ys) = x == y && xs == ys
282 instance (Ord a) => Ord [a] where
283 {-# SPECIALISE instance Ord [Char] #-}
285 compare [] (_:_) = LT
286 compare (_:_) [] = GT
287 compare (x:xs) (y:ys) = case compare x y of
291 instance Functor [] where
294 instance Monad [] where
295 m >>= k = foldr ((++) . k) [] m
296 m >> k = foldr ((++) . (\ _ -> k)) [] m
301 A few list functions that appear here because they are used here.
302 The rest of the prelude list functions are in GHC.List.
304 ----------------------------------------------
305 -- foldr/build/augment
306 ----------------------------------------------
309 -- | 'foldr', applied to a binary operator, a starting value (typically
310 -- the right-identity of the operator), and a list, reduces the list
311 -- using the binary operator, from right to left:
313 -- > foldr f z [x1, x2, ..., xn] == x1 `f` (x2 `f` ... (xn `f` z)...)
315 foldr :: (a -> b -> b) -> b -> [a] -> b
317 -- foldr f z (x:xs) = f x (foldr f z xs)
318 {-# INLINE [0] foldr #-}
319 -- Inline only in the final stage, after the foldr/cons rule has had a chance
323 go (y:ys) = y `k` go ys
325 -- | A list producer that can be fused with 'foldr'.
326 -- This function is merely
328 -- > build g = g (:) []
330 -- but GHC's simplifier will transform an expression of the form
331 -- @'foldr' k z ('build' g)@, which may arise after inlining, to @g k z@,
332 -- which avoids producing an intermediate list.
334 build :: forall a. (forall b. (a -> b -> b) -> b -> b) -> [a]
335 {-# INLINE [1] build #-}
336 -- The INLINE is important, even though build is tiny,
337 -- because it prevents [] getting inlined in the version that
338 -- appears in the interface file. If [] *is* inlined, it
339 -- won't match with [] appearing in rules in an importing module.
341 -- The "1" says to inline in phase 1
345 -- | A list producer that can be fused with 'foldr'.
346 -- This function is merely
348 -- > augment g xs = g (:) xs
350 -- but GHC's simplifier will transform an expression of the form
351 -- @'foldr' k z ('augment' g xs)@, which may arise after inlining, to
352 -- @g k ('foldr' k z xs)@, which avoids producing an intermediate list.
354 augment :: forall a. (forall b. (a->b->b) -> b -> b) -> [a] -> [a]
355 {-# INLINE [1] augment #-}
356 augment g xs = g (:) xs
359 "fold/build" forall k z (g::forall b. (a->b->b) -> b -> b) .
360 foldr k z (build g) = g k z
362 "foldr/augment" forall k z xs (g::forall b. (a->b->b) -> b -> b) .
363 foldr k z (augment g xs) = g k (foldr k z xs)
365 "foldr/id" foldr (:) [] = \x -> x
366 "foldr/app" [1] forall ys. foldr (:) ys = \xs -> xs ++ ys
367 -- Only activate this from phase 1, because that's
368 -- when we disable the rule that expands (++) into foldr
370 -- The foldr/cons rule looks nice, but it can give disastrously
371 -- bloated code when commpiling
372 -- array (a,b) [(1,2), (2,2), (3,2), ...very long list... ]
373 -- i.e. when there are very very long literal lists
374 -- So I've disabled it for now. We could have special cases
375 -- for short lists, I suppose.
376 -- "foldr/cons" forall k z x xs. foldr k z (x:xs) = k x (foldr k z xs)
378 "foldr/single" forall k z x. foldr k z [x] = k x z
379 "foldr/nil" forall k z. foldr k z [] = z
381 "augment/build" forall (g::forall b. (a->b->b) -> b -> b)
382 (h::forall b. (a->b->b) -> b -> b) .
383 augment g (build h) = build (\c n -> g c (h c n))
384 "augment/nil" forall (g::forall b. (a->b->b) -> b -> b) .
385 augment g [] = build g
388 -- This rule is true, but not (I think) useful:
389 -- augment g (augment h t) = augment (\cn -> g c (h c n)) t
393 ----------------------------------------------
395 ----------------------------------------------
398 -- | 'map' @f xs@ is the list obtained by applying @f@ to each element
401 -- > map f [x1, x2, ..., xn] == [f x1, f x2, ..., f xn]
402 -- > map f [x1, x2, ...] == [f x1, f x2, ...]
404 map :: (a -> b) -> [a] -> [b]
406 map f (x:xs) = f x : map f xs
409 mapFB :: (elt -> lst -> lst) -> (a -> elt) -> a -> lst -> lst
410 {-# INLINE [0] mapFB #-}
411 mapFB c f x ys = c (f x) ys
413 -- The rules for map work like this.
415 -- Up to (but not including) phase 1, we use the "map" rule to
416 -- rewrite all saturated applications of map with its build/fold
417 -- form, hoping for fusion to happen.
418 -- In phase 1 and 0, we switch off that rule, inline build, and
419 -- switch on the "mapList" rule, which rewrites the foldr/mapFB
420 -- thing back into plain map.
422 -- It's important that these two rules aren't both active at once
423 -- (along with build's unfolding) else we'd get an infinite loop
424 -- in the rules. Hence the activation control below.
426 -- The "mapFB" rule optimises compositions of map.
428 -- This same pattern is followed by many other functions:
429 -- e.g. append, filter, iterate, repeat, etc.
432 "map" [~1] forall f xs. map f xs = build (\c n -> foldr (mapFB c f) n xs)
433 "mapList" [1] forall f. foldr (mapFB (:) f) [] = map f
434 "mapFB" forall c f g. mapFB (mapFB c f) g = mapFB c (f.g)
439 ----------------------------------------------
441 ----------------------------------------------
443 -- | Append two lists, i.e.,
445 -- > [x1, ..., xm] ++ [y1, ..., yn] == [x1, ..., xm, y1, ..., yn]
446 -- > [x1, ..., xm] ++ [y1, ...] == [x1, ..., xm, y1, ...]
448 -- If the first list is not finite, the result is the first list.
450 (++) :: [a] -> [a] -> [a]
452 (++) (x:xs) ys = x : xs ++ ys
455 "++" [~1] forall xs ys. xs ++ ys = augment (\c n -> foldr c n xs) ys
461 %*********************************************************
463 \subsection{Type @Bool@}
465 %*********************************************************
468 -- |The 'Bool' type is an enumeration. It is defined with 'False'
469 -- first so that the corresponding 'Prelude.Enum' instance will give
470 -- 'Prelude.fromEnum' 'False' the value zero, and
471 -- 'Prelude.fromEnum' 'True' the value 1.
472 data Bool = False | True deriving (Eq, Ord)
473 -- Read in GHC.Read, Show in GHC.Show
478 (&&) :: Bool -> Bool -> Bool
483 (||) :: Bool -> Bool -> Bool
492 -- |'otherwise' is defined as the value 'True'. It helps to make
493 -- guards more readable. eg.
495 -- > f x | x < 0 = ...
496 -- > | otherwise = ...
502 %*********************************************************
504 \subsection{The @()@ type}
506 %*********************************************************
508 The Unit type is here because virtually any program needs it (whereas
509 some programs may get away without consulting GHC.Tup). Furthermore,
510 the renamer currently *always* asks for () to be in scope, so that
511 ccalls can use () as their default type; so when compiling GHC.Base we
512 need (). (We could arrange suck in () only if -fglasgow-exts, but putting
513 it here seems more direct.)
516 -- | The unit datatype @()@ has one non-undefined member, the nullary
524 instance Ord () where
535 %*********************************************************
537 \subsection{Type @Ordering@}
539 %*********************************************************
542 -- | Represents an ordering relationship between two values: less
543 -- than, equal to, or greater than. An 'Ordering' is returned by
545 data Ordering = LT | EQ | GT deriving (Eq, Ord)
546 -- Read in GHC.Read, Show in GHC.Show
550 %*********************************************************
552 \subsection{Type @Char@ and @String@}
554 %*********************************************************
557 -- | A 'String' is a list of characters. String constants in Haskell are values
562 {-| The character type 'Char' is an enumeration whose values represent
563 Unicode (or equivalently ISO\/IEC 10646) characters
564 (see <http://www.unicode.org/> for details).
565 This set extends the ISO 8859-1 (Latin-1) character set
566 (the first 256 charachers), which is itself an extension of the ASCII
567 character set (the first 128 characters).
568 A character literal in Haskell has type 'Char'.
570 To convert a 'Char' to or from the corresponding 'Int' value defined
571 by Unicode, use 'Prelude.toEnum' and 'Prelude.fromEnum' from the
572 'Prelude.Enum' class respectively (or equivalently 'ord' and 'chr').
576 -- We don't use deriving for Eq and Ord, because for Ord the derived
577 -- instance defines only compare, which takes two primops. Then
578 -- '>' uses compare, and therefore takes two primops instead of one.
580 instance Eq Char where
581 (C# c1) == (C# c2) = c1 `eqChar#` c2
582 (C# c1) /= (C# c2) = c1 `neChar#` c2
584 instance Ord Char where
585 (C# c1) > (C# c2) = c1 `gtChar#` c2
586 (C# c1) >= (C# c2) = c1 `geChar#` c2
587 (C# c1) <= (C# c2) = c1 `leChar#` c2
588 (C# c1) < (C# c2) = c1 `ltChar#` c2
591 "x# `eqChar#` x#" forall x#. x# `eqChar#` x# = True
592 "x# `neChar#` x#" forall x#. x# `neChar#` x# = False
593 "x# `gtChar#` x#" forall x#. x# `gtChar#` x# = False
594 "x# `geChar#` x#" forall x#. x# `geChar#` x# = True
595 "x# `leChar#` x#" forall x#. x# `leChar#` x# = True
596 "x# `ltChar#` x#" forall x#. x# `ltChar#` x# = False
599 -- | The 'Prelude.toEnum' method restricted to the type 'Data.Char.Char'.
601 chr (I# i#) | int2Word# i# `leWord#` int2Word# 0x10FFFF# = C# (chr# i#)
602 | otherwise = error "Prelude.chr: bad argument"
604 unsafeChr :: Int -> Char
605 unsafeChr (I# i#) = C# (chr# i#)
607 -- | The 'Prelude.fromEnum' method restricted to the type 'Data.Char.Char'.
609 ord (C# c#) = I# (ord# c#)
612 String equality is used when desugaring pattern-matches against strings.
615 eqString :: String -> String -> Bool
616 eqString [] [] = True
617 eqString (c1:cs1) (c2:cs2) = c1 == c2 && cs1 `eqString` cs2
618 eqString cs1 cs2 = False
620 {-# RULES "eqString" (==) = eqString #-}
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 -- lazy function; this is just the same as id, but its unfolding
687 -- and strictness are over-ridden by the definition in MkId.lhs
688 -- That way, it does not get inlined, and the strictness analyser
689 -- sees it as lazy. Then the worker/wrapper phase inlines it.
694 -- Assertion function. This simply ignores its boolean argument.
695 -- The compiler may rewrite it to @('assertError' line)@.
697 -- | If the first argument evaluates to 'True', then the result is the
698 -- second argument. Otherwise an 'AssertionFailed' exception is raised,
699 -- containing a 'String' with the source file and line number of the
702 -- Assertions can normally be turned on or off with a compiler flag
703 -- (for GHC, assertions are normally on unless optimisation is turned on
704 -- with @-O@ or the @-fignore-asserts@
705 -- option is given). When assertions are turned off, the first
706 -- argument to 'assert' is ignored, and the second argument is
707 -- returned as the result.
709 -- SLPJ: in 5.04 etc 'assert' is in GHC.Prim,
710 -- but from Template Haskell onwards it's simply
711 -- defined here in Base.lhs
712 assert :: Bool -> a -> a
718 -- | Constant function.
722 -- | Function composition.
724 (.) :: (b -> c) -> (a -> b) -> a -> c
727 -- | @'flip' f@ takes its (first) two arguments in the reverse order of @f@.
728 flip :: (a -> b -> c) -> b -> a -> c
731 -- | Application operator. This operator is redundant, since ordinary
732 -- application @(f x)@ means the same as @(f '$' x)@. However, '$' has
733 -- low, right-associative binding precedence, so it sometimes allows
734 -- parentheses to be omitted; for example:
736 -- > f $ g $ h x = f (g (h x))
738 -- It is also useful in higher-order situations, such as @'map' ('$' 0) xs@,
739 -- or @'Data.List.zipWith' ('$') fs xs@.
741 ($) :: (a -> b) -> a -> b
744 -- | @'until' p f@ yields the result of applying @f@ until @p@ holds.
745 until :: (a -> Bool) -> (a -> a) -> a -> a
746 until p f x | p x = x
747 | otherwise = until p f (f x)
749 -- | 'asTypeOf' is a type-restricted version of 'const'. It is usually
750 -- used as an infix operator, and its typing forces its first argument
751 -- (which is usually overloaded) to have the same type as the second.
752 asTypeOf :: a -> a -> a
756 %*********************************************************
758 \subsection{Generics}
760 %*********************************************************
765 data (:+:) a b = Inl a | Inr b
766 data (:*:) a b = a :*: b
770 %*********************************************************
772 \subsection{@getTag@}
774 %*********************************************************
776 Returns the 'tag' of a constructor application; this function is used
777 by the deriving code for Eq, Ord and Enum.
779 The primitive dataToTag# requires an evaluated constructor application
780 as its argument, so we provide getTag as a wrapper that performs the
781 evaluation before calling dataToTag#. We could have dataToTag#
782 evaluate its argument, but we prefer to do it this way because (a)
783 dataToTag# can be an inline primop if it doesn't need to do any
784 evaluation, and (b) we want to expose the evaluation to the
785 simplifier, because it might be possible to eliminate the evaluation
786 in the case when the argument is already known to be evaluated.
789 {-# INLINE getTag #-}
791 getTag x = x `seq` dataToTag# x
794 %*********************************************************
796 \subsection{Numeric primops}
798 %*********************************************************
801 divInt# :: Int# -> Int# -> Int#
803 -- Be careful NOT to overflow if we do any additional arithmetic
804 -- on the arguments... the following previous version of this
805 -- code has problems with overflow:
806 -- | (x# ># 0#) && (y# <# 0#) = ((x# -# y#) -# 1#) `quotInt#` y#
807 -- | (x# <# 0#) && (y# ># 0#) = ((x# -# y#) +# 1#) `quotInt#` y#
808 | (x# ># 0#) && (y# <# 0#) = ((x# -# 1#) `quotInt#` y#) -# 1#
809 | (x# <# 0#) && (y# ># 0#) = ((x# +# 1#) `quotInt#` y#) -# 1#
810 | otherwise = x# `quotInt#` y#
812 modInt# :: Int# -> Int# -> Int#
814 | (x# ># 0#) && (y# <# 0#) ||
815 (x# <# 0#) && (y# ># 0#) = if r# /=# 0# then r# +# y# else 0#
821 Definitions of the boxed PrimOps; these will be
822 used in the case of partial applications, etc.
831 {-# INLINE plusInt #-}
832 {-# INLINE minusInt #-}
833 {-# INLINE timesInt #-}
834 {-# INLINE quotInt #-}
835 {-# INLINE remInt #-}
836 {-# INLINE negateInt #-}
838 plusInt, minusInt, timesInt, quotInt, remInt, divInt, modInt, gcdInt :: Int -> Int -> Int
839 (I# x) `plusInt` (I# y) = I# (x +# y)
840 (I# x) `minusInt` (I# y) = I# (x -# y)
841 (I# x) `timesInt` (I# y) = I# (x *# y)
842 (I# x) `quotInt` (I# y) = I# (x `quotInt#` y)
843 (I# x) `remInt` (I# y) = I# (x `remInt#` y)
844 (I# x) `divInt` (I# y) = I# (x `divInt#` y)
845 (I# x) `modInt` (I# y) = I# (x `modInt#` y)
848 "x# +# 0#" forall x#. x# +# 0# = x#
849 "0# +# x#" forall x#. 0# +# x# = x#
850 "x# -# 0#" forall x#. x# -# 0# = x#
851 "x# -# x#" forall x#. x# -# x# = 0#
852 "x# *# 0#" forall x#. x# *# 0# = 0#
853 "0# *# x#" forall x#. 0# *# x# = 0#
854 "x# *# 1#" forall x#. x# *# 1# = x#
855 "1# *# x#" forall x#. 1# *# x# = x#
858 gcdInt (I# a) (I# b) = g a b
859 where g 0# 0# = error "GHC.Base.gcdInt: gcd 0 0 is undefined"
862 g _ _ = I# (gcdInt# absA absB)
864 absInt x = if x <# 0# then negateInt# x else x
869 negateInt :: Int -> Int
870 negateInt (I# x) = I# (negateInt# x)
872 gtInt, geInt, eqInt, neInt, ltInt, leInt :: Int -> Int -> Bool
873 (I# x) `gtInt` (I# y) = x ># y
874 (I# x) `geInt` (I# y) = x >=# y
875 (I# x) `eqInt` (I# y) = x ==# y
876 (I# x) `neInt` (I# y) = x /=# y
877 (I# x) `ltInt` (I# y) = x <# y
878 (I# x) `leInt` (I# y) = x <=# y
881 "x# ># x#" forall x#. x# ># x# = False
882 "x# >=# x#" forall x#. x# >=# x# = True
883 "x# ==# x#" forall x#. x# ==# x# = True
884 "x# /=# x#" forall x#. x# /=# x# = False
885 "x# <# x#" forall x#. x# <# x# = False
886 "x# <=# x#" forall x#. x# <=# x# = True
890 "plusFloat x 0.0" forall x#. plusFloat# x# 0.0# = x#
891 "plusFloat 0.0 x" forall x#. plusFloat# 0.0# x# = x#
892 "minusFloat x 0.0" forall x#. minusFloat# x# 0.0# = x#
893 "minusFloat x x" forall x#. minusFloat# x# x# = 0.0#
894 "timesFloat x 0.0" forall x#. timesFloat# x# 0.0# = 0.0#
895 "timesFloat0.0 x" forall x#. timesFloat# 0.0# x# = 0.0#
896 "timesFloat x 1.0" forall x#. timesFloat# x# 1.0# = x#
897 "timesFloat 1.0 x" forall x#. timesFloat# 1.0# x# = x#
898 "divideFloat x 1.0" forall x#. divideFloat# x# 1.0# = x#
902 "plusDouble x 0.0" forall x#. (+##) x# 0.0## = x#
903 "plusDouble 0.0 x" forall x#. (+##) 0.0## x# = x#
904 "minusDouble x 0.0" forall x#. (-##) x# 0.0## = x#
905 "minusDouble x x" forall x#. (-##) x# x# = 0.0##
906 "timesDouble x 0.0" forall x#. (*##) x# 0.0## = 0.0##
907 "timesDouble 0.0 x" forall x#. (*##) 0.0## x# = 0.0##
908 "timesDouble x 1.0" forall x#. (*##) x# 1.0## = x#
909 "timesDouble 1.0 x" forall x#. (*##) 1.0## x# = x#
910 "divideDouble x 1.0" forall x#. (/##) x# 1.0## = x#
913 -- Wrappers for the shift operations. The uncheckedShift# family are
914 -- undefined when the amount being shifted by is greater than the size
915 -- in bits of Int#, so these wrappers perform a check and return
916 -- either zero or -1 appropriately.
918 -- Note that these wrappers still produce undefined results when the
919 -- second argument (the shift amount) is negative.
921 -- | Shift the argument left by the specified number of bits
922 -- (which must be non-negative).
923 shiftL# :: Word# -> Int# -> Word#
924 a `shiftL#` b | b >=# WORD_SIZE_IN_BITS# = int2Word# 0#
925 | otherwise = a `uncheckedShiftL#` b
927 -- | Shift the argument right by the specified number of bits
928 -- (which must be non-negative).
929 shiftRL# :: Word# -> Int# -> Word#
930 a `shiftRL#` b | b >=# WORD_SIZE_IN_BITS# = int2Word# 0#
931 | otherwise = a `uncheckedShiftRL#` b
933 -- | Shift the argument left by the specified number of bits
934 -- (which must be non-negative).
935 iShiftL# :: Int# -> Int# -> Int#
936 a `iShiftL#` b | b >=# WORD_SIZE_IN_BITS# = 0#
937 | otherwise = a `uncheckedIShiftL#` b
939 -- | Shift the argument right (signed) by the specified number of bits
940 -- (which must be non-negative).
941 iShiftRA# :: Int# -> Int# -> Int#
942 a `iShiftRA#` b | b >=# WORD_SIZE_IN_BITS# = if a <# 0# then (-1#) else 0#
943 | otherwise = a `uncheckedIShiftRA#` b
945 -- | Shift the argument right (unsigned) by the specified number of bits
946 -- (which must be non-negative).
947 iShiftRL# :: Int# -> Int# -> Int#
948 a `iShiftRL#` b | b >=# WORD_SIZE_IN_BITS# = 0#
949 | otherwise = a `uncheckedIShiftRL#` b
951 #if WORD_SIZE_IN_BITS == 32
953 "narrow32Int#" forall x#. narrow32Int# x# = x#
954 "narrow32Word#" forall x#. narrow32Word# x# = x#
959 "int2Word2Int" forall x#. int2Word# (word2Int# x#) = x#
960 "word2Int2Word" forall x#. word2Int# (int2Word# x#) = x#
965 %********************************************************
967 \subsection{Unpacking C strings}
969 %********************************************************
971 This code is needed for virtually all programs, since it's used for
972 unpacking the strings of error messages.
975 unpackCString# :: Addr# -> [Char]
976 {-# NOINLINE [1] unpackCString# #-}
981 | ch `eqChar#` '\0'# = []
982 | otherwise = C# ch : unpack (nh +# 1#)
984 ch = indexCharOffAddr# addr nh
986 unpackAppendCString# :: Addr# -> [Char] -> [Char]
987 unpackAppendCString# addr rest
991 | ch `eqChar#` '\0'# = rest
992 | otherwise = C# ch : unpack (nh +# 1#)
994 ch = indexCharOffAddr# addr nh
996 unpackFoldrCString# :: Addr# -> (Char -> a -> a) -> a -> a
997 {-# NOINLINE [0] unpackFoldrCString# #-}
998 -- Don't inline till right at the end;
999 -- usually the unpack-list rule turns it into unpackCStringList
1000 unpackFoldrCString# addr f z
1004 | ch `eqChar#` '\0'# = z
1005 | otherwise = C# ch `f` unpack (nh +# 1#)
1007 ch = indexCharOffAddr# addr nh
1009 unpackCStringUtf8# :: Addr# -> [Char]
1010 unpackCStringUtf8# addr
1014 | ch `eqChar#` '\0'# = []
1015 | ch `leChar#` '\x7F'# = C# ch : unpack (nh +# 1#)
1016 | ch `leChar#` '\xDF'# =
1017 C# (chr# (((ord# ch -# 0xC0#) `uncheckedIShiftL#` 6#) +#
1018 (ord# (indexCharOffAddr# addr (nh +# 1#)) -# 0x80#))) :
1020 | ch `leChar#` '\xEF'# =
1021 C# (chr# (((ord# ch -# 0xE0#) `uncheckedIShiftL#` 12#) +#
1022 ((ord# (indexCharOffAddr# addr (nh +# 1#)) -# 0x80#) `uncheckedIShiftL#` 6#) +#
1023 (ord# (indexCharOffAddr# addr (nh +# 2#)) -# 0x80#))) :
1026 C# (chr# (((ord# ch -# 0xF0#) `uncheckedIShiftL#` 18#) +#
1027 ((ord# (indexCharOffAddr# addr (nh +# 1#)) -# 0x80#) `uncheckedIShiftL#` 12#) +#
1028 ((ord# (indexCharOffAddr# addr (nh +# 2#)) -# 0x80#) `uncheckedIShiftL#` 6#) +#
1029 (ord# (indexCharOffAddr# addr (nh +# 3#)) -# 0x80#))) :
1032 ch = indexCharOffAddr# addr nh
1034 unpackNBytes# :: Addr# -> Int# -> [Char]
1035 unpackNBytes# _addr 0# = []
1036 unpackNBytes# addr len# = unpack [] (len# -# 1#)
1041 case indexCharOffAddr# addr i# of
1042 ch -> unpack (C# ch : acc) (i# -# 1#)
1045 "unpack" [~1] forall a . unpackCString# a = build (unpackFoldrCString# a)
1046 "unpack-list" [1] forall a . unpackFoldrCString# a (:) [] = unpackCString# a
1047 "unpack-append" forall a n . unpackFoldrCString# a (:) n = unpackAppendCString# a n
1049 -- There's a built-in rule (in PrelRules.lhs) for
1050 -- unpackFoldr "foo" c (unpackFoldr "baz" c n) = unpackFoldr "foobaz" c n
1057 -- | A special argument for the 'Control.Monad.ST.ST' type constructor,
1058 -- indexing a state embedded in the 'Prelude.IO' monad by
1059 -- 'Control.Monad.ST.stToIO'.