Prelude.hs

    {-# LANGUAGE Trustworthy #-}
    {-# LANGUAGE NoImplicitPrelude #-}

    -----------------------------------------------------------------------------
    -- |
    -- Module      :  Prelude
    -- Copyright   :  (c) The University of Glasgow 2001
    -- License     :  BSD-style (see the file libraries/base/LICENSE)
    --
    -- Maintainer  :  libraries@haskell.org
    -- Stability   :  stable
    -- Portability :  portable
    --
    -- The Prelude: a standard module. The Prelude is imported by default
    -- into all Haskell modules unless either there is an explicit import
    -- statement for it, or the NoImplicitPrelude extension is enabled.
    --
    -----------------------------------------------------------------------------

    module Prelude (

        -- * Standard types, classes and related functions

        -- ** Basic data types
        Bool(False, True),
        (&&), (||), not, otherwise,

        Maybe(Nothing, Just),
        maybe,

        Either(Left, Right),
        either,

        Ordering(LT, EQ, GT),
        Char, String,

        -- *** Tuples
        fst, snd, curry, uncurry,

        -- ** Basic type classes
        Eq((==), (/=)),
        Ord(compare, (<), (<=), (>=), (>), max, min),
        Enum(succ, pred, toEnum, fromEnum, enumFrom, enumFromThen,
             enumFromTo, enumFromThenTo),
        Bounded(minBound, maxBound),

        -- ** Numbers

        -- *** Numeric types
        Int, Integer, Float, Double,
        Rational, Word,

        -- *** Numeric type classes
        Num((+), (-), (*), negate, abs, signum, fromInteger),
        Real(toRational),
        Integral(quot, rem, div, mod, quotRem, divMod, toInteger),
        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, atan2),

        -- *** Numeric functions
        subtract, even, odd, gcd, lcm, (^), (^^),
        fromIntegral, realToFrac,

        -- ** Monoids
        Monoid(mempty, mappend, mconcat),

        -- ** Monads and functors
        Functor(fmap, (<$)), (<$>),
        Applicative(pure, (<*>), (*>), (<*)),
        Monad((>>=), (>>), return, fail),
        mapM_, sequence_, (=<<),

        -- ** Folds and traversals
        Foldable(elem,      -- :: (Foldable t, Eq a) => a -> t a -> Bool
                 -- fold,   -- :: Monoid m => t m -> m
                 foldMap,   -- :: Monoid m => (a -> m) -> t a -> m
                 foldr,     -- :: (a -> b -> b) -> b -> t a -> b
                 -- foldr', -- :: (a -> b -> b) -> b -> t a -> b
                 foldl,     -- :: (b -> a -> b) -> b -> t a -> b
                 -- foldl', -- :: (b -> a -> b) -> b -> t a -> b
                 foldr1,    -- :: (a -> a -> a) -> t a -> a
                 foldl1,    -- :: (a -> a -> a) -> t a -> a
                 maximum,   -- :: (Foldable t, Ord a) => t a -> a
                 minimum,   -- :: (Foldable t, Ord a) => t a -> a
                 product,   -- :: (Foldable t, Num a) => t a -> a
                 sum),      -- :: Num a => t a -> a
                 -- toList) -- :: Foldable t => t a -> [a]

        Traversable(traverse, sequenceA, mapM, sequence),

        -- ** Miscellaneous functions
        id, const, (.), flip, ($), until,
        asTypeOf, error, errorWithoutStackTrace, undefined,
        seq, ($!),

        -- * List operations
        map, (++), filter,
        head, last, tail, init, null, length, (!!),
        reverse,
        -- *** Special folds
        and, or, any, all,
        concat, concatMap,
        -- ** Building lists
        -- *** Scans
        scanl, scanl1, scanr, scanr1,
        -- *** Infinite lists
        iterate, repeat, replicate, cycle,
        -- ** Sublists
        take, drop, splitAt, takeWhile, dropWhile, span, break,
        -- ** Searching lists
        notElem, lookup,
        -- ** Zipping and unzipping lists
        zip, zip3, zipWith, zipWith3, unzip, unzip3,
        -- ** Functions on strings
        lines, words, unlines, unwords,

        -- * Converting to and from @String@
        -- ** Converting to @String@
        ShowS,
        Show(showsPrec, showList, show),
        shows,
        showChar, showString, showParen,
        -- ** Converting from @String@
        ReadS,
        Read(readsPrec, readList),
        reads, readParen, read, lex,

        -- * Basic Input and output
        IO,
        -- ** Simple I\/O operations
        -- All I/O functions defined here are character oriented.  The
        -- treatment of the newline character will vary on different systems.
        -- For example, two characters of input, return and linefeed, may
        -- read as a single newline character.  These functions cannot be
        -- used portably for binary I/O.
        -- *** Output functions
        putChar,
        putStr, putStrLn, print,
        -- *** Input functions
        getChar,
        getLine, getContents, interact,
        -- *** Files
        FilePath,
        readFile, writeFile, appendFile, readIO, readLn,
        -- ** Exception handling in the I\/O monad
        IOError, ioError, userError,

      ) where

    import Control.Monad
    import System.IO
    import System.IO.Error
    import Data.List
    import Data.Either
    import Data.Foldable    ( Foldable(..) )
    import Data.Functor     ( (<$>) )
    import Data.Maybe
    import Data.Traversable ( Traversable(..) )
    import Data.Tuple

    import GHC.Base hiding ( foldr, mapM, sequence )
    import Text.Read
    import GHC.Enum
    import GHC.Num
    import GHC.Real
    import GHC.Float
    import GHC.Show