+% ------------------------------------------------------------------------------
+% $Id: Prelude.lhs,v 1.26 2001/05/18 16:54:05 simonmar Exp $
+%
+% (c) The University of Glasgow, 1992-2000
+%
+
+\section[Prelude]{Module @Prelude@}
+
We add the option -fno-implicit-prelude here to tell the reader that
special names such as () and -> shouldn't be resolved to Prelude.()
and Prelude.-> (as they are normally). -- SDM 8/10/97
module Prelude (
- -- Everything from these modules
- module PrelList,
- module PrelIO,
+ -- Everything corresponding to the Report's PreludeList
+ module PrelList,
+ lines, words, unlines, unwords,
+ sum, product,
+
+ -- Everything corresponding to the Report's PreludeText
+ ReadS, ShowS,
+ Read(readsPrec, readList),
+ Show(showsPrec, showList, show),
+ reads, shows, read, lex,
+ showChar, showString, readParen, showParen,
+
+ -- Everything corresponding to the Report's PreludeIO
+ ioError, userError, catch,
+ FilePath, IOError,
+ putChar,
+ putStr, putStrLn, print,
+ getChar,
+ getLine, getContents, interact,
+ readFile, writeFile, appendFile, readIO, readLn,
+
+ Bool(..),
+ Maybe(..),
+ Either(..),
+ Ordering(..),
+ Char, String, Int, Integer, Float, Double, IO,
+ Rational,
+ []((:), []),
+
module PrelTup,
-
- -- From PrelBase
- (->),
- Eq(..),
- Ord(..), Ordering(..),
- Bounded(..),
- Enum(..), succ, pred,
- Show(..), ShowS, shows, show, showChar, showString, showParen,
- Eval(..), seq, strict,
- Bool(..), (&&), (||), not, otherwise,
- Char, String, Int, Integer, Float, Double, Void,
- Maybe(..), maybe,
- Either(..), either,
+ -- Includes tuple types + fst, snd, curry, uncurry
()(..), -- The unit type
-
+ (->), -- functions
- id, const, (.), flip, ($), until, asTypeOf, undefined,
-
- -- From Error
- error,
-
- -- From Monad
- Functor(..), Monad(..), MonadZero(..), MonadPlus(..),
- accumulate, sequence, mapM, mapM_, guard, filter, concat, applyM,
-
- -- From PrelRead
- ReadS, Read(readsPrec, readList),
- reads, read, lex, readParen,
-
- -- From PrelShow
-
- -- From PrelNum
- Ratio, Rational,
- (%), numerator, denominator, approxRational,
-
- Num((+), (-), (*), negate, abs, signum, fromInteger, fromInt{-glaExt-}),
- Real(toRational),
- Integral(quot, rem, div, mod, quotRem, divMod, toInteger, toInt{-partain-}),
- Fractional((/), recip, fromRational),
- Floating(pi, exp, log, sqrt, (**), logBase, sin, cos, tan,
- asin, acos, atan, sinh, cosh, tanh, asinh, acosh, atanh),
- RealFrac(properFraction, truncate, round, ceiling, floor),
- RealFloat(floatRadix, floatDigits, floatRange, decodeFloat,
- encodeFloat, exponent, significand, scaleFloat, isNaN,
- isInfinite, isDenormalized, isIEEE, isNegativeZero),
+ Eq(..),
+ Ord(..),
+ Enum(..),
+ Bounded(..),
+ Num(..),
+ Real(..),
+ Integral(..),
+ Fractional(..),
+ Floating(..),
+ RealFrac(..),
+ RealFloat(..),
+
+ -- Monad stuff, from PrelBase, and defined here
+ Monad(..),
+ Functor(..),
+ mapM, mapM_, sequence, sequence_, (=<<),
+
+ maybe, either,
+ (&&), (||), not, otherwise,
subtract, even, odd, gcd, lcm, (^), (^^),
- fromIntegral, fromRealFrac, atan2
+ fromIntegral, realToFrac,
+ --exported by PrelTup: fst, snd, curry, uncurry,
+ id, const, (.), flip, ($), until,
+ asTypeOf, error, undefined,
+ seq, ($!)
+
) where
+import Monad
+
import PrelBase
import PrelList
+#ifndef USE_REPORT_PRELUDE
+ hiding ( takeUInt_append )
+#endif
import PrelIO
+import PrelIOBase
+import PrelException
import PrelRead
+import PrelEnum
import PrelNum
+import PrelReal
+import PrelFloat
import PrelTup
import PrelMaybe
-import PrelEither
-import PrelBounded
-import Monad
-import Maybe
-import PrelErr ( error, seqError )
-
--- These can't conveniently be defined in PrelBase because they use numbers,
--- or I/O, so here's a convenient place to do them.
+import PrelShow
+import PrelConc
+import PrelErr ( error, undefined )
-strict :: Eval a => (a -> b) -> a -> b
-strict f x = x `seq` f x
+infixr 0 $!
+\end{code}
--- "seq" is defined a bit wierdly (see below)
---
--- The reason for the strange "0# -> parError" case is that
--- it fools the compiler into thinking that seq is non-strict in
--- its second argument (even if it inlines seq at the call site).
--- If it thinks seq is strict in "y", then it often evaluates
--- "y" before "x", which is totally wrong.
---
--- Just before converting from Core to STG there's a bit of magic
--- that recognises the seq# and eliminates the duff case.
+%*********************************************************
+%* *
+\subsection{Miscellaneous functions}
+%* *
+%*********************************************************
-{-# INLINE seq #-}
-seq :: Eval a => a -> b -> b
-seq x y = case (seq# x) of { 0# -> seqError; _ -> y }
+\begin{code}
+($!) :: (a -> b) -> a -> b
+f $! x = x `seq` f x
+\end{code}
--- It is expected that compilers will recognize this and insert error
--- messages which are more appropriate to the context in which undefined
--- appears.
-undefined :: a
-undefined = error "Prelude.undefined"
-\end{code}
+%*********************************************************
+%* *
+\subsection{List sum and product}
+%* *
+%*********************************************************
+List sum and product are defined here because PrelList is too far
+down the compilation chain to "see" the Num class.
+\begin{code}
+-- sum and product compute the sum or product of a finite list of numbers.
+{-# SPECIALISE sum :: [Int] -> Int #-}
+{-# SPECIALISE sum :: [Integer] -> Integer #-}
+{-# SPECIALISE product :: [Int] -> Int #-}
+{-# SPECIALISE product :: [Integer] -> Integer #-}
+sum, product :: (Num a) => [a] -> a
+#ifdef USE_REPORT_PRELUDE
+sum = foldl (+) 0
+product = foldl (*) 1
+#else
+sum l = sum' l 0
+ where
+ sum' [] a = a
+ sum' (x:xs) a = sum' xs (a+x)
+product l = prod l 1
+ where
+ prod [] a = a
+ prod (x:xs) a = prod xs (a*x)
+#endif
+\end{code}
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