{-# LANGUAGE CPP #-} -- | -- This module reexports most of the definitions from the \"base\" package, -- which are meant to be imported unqualified. -- -- For details check out the source. module BasePrelude ( module Exports, -- * Reimplementations of functions presented in versions of \"base\" newer than 4.6 -- ** Data.Bool bool, -- ** Data.Function (&), -- ** Data.Functor ($>), -- ** Data.List isSubsequenceOf, sortOn, uncons, -- ** Debug.Trace traceShowId, traceM, traceShowM, ) where -- Reexports ------------------------- import Control.Applicative as Exports import Control.Arrow as Exports hiding (first, second) import Control.Category as Exports import Control.Concurrent as Exports import Control.Exception as Exports import Control.Monad as Exports hiding (mapM_, sequence_, forM_, msum, mapM, sequence, forM) import Control.Monad.Fix as Exports hiding (fix) import Control.Monad.ST as Exports #if MIN_VERSION_base(4,8,0) import Data.Bifunctor as Exports #endif import Data.Bits as Exports import Data.Bool as Exports hiding (bool) import Data.Char as Exports import Data.Complex as Exports import Data.Data as Exports import Data.Dynamic as Exports import Data.Either as Exports import Data.Fixed as Exports import Data.Foldable as Exports import Data.Functor as Exports hiding (($>)) import Data.Function as Exports hiding ((.), id, (&)) import Data.Int as Exports import Data.IORef as Exports import Data.Ix as Exports import Data.List as Exports hiding (sortOn, isSubsequenceOf, uncons, concat, foldr, foldl1, maximum, minimum, product, sum, all, and, any, concatMap, elem, foldl, foldr1, notElem, or, find, maximumBy, minimumBy, mapAccumL, mapAccumR, foldl') import Data.Maybe as Exports import Data.Monoid as Exports import Data.Ord as Exports import Data.Ratio as Exports import Data.STRef as Exports import Data.String as Exports import Data.Traversable as Exports import Data.Tuple as Exports import Data.Unique as Exports import Data.Version as Exports import Data.Word as Exports import Debug.Trace as Exports hiding (traceShowId, traceM, traceShowM) import Foreign.Storable as Exports import Foreign.Ptr as Exports import Foreign.ForeignPtr as Exports import Foreign.StablePtr as Exports import GHC.Conc as Exports hiding (withMVar, threadWaitWriteSTM, threadWaitWrite, threadWaitReadSTM, threadWaitRead) import GHC.Exts as Exports (lazy, inline, sortWith, groupWith) import GHC.Generics as Exports (Generic) import GHC.IO.Exception as Exports import Numeric as Exports import Prelude as Exports hiding (concat, foldr, mapM_, sequence_, foldl1, maximum, minimum, product, sum, all, and, any, concatMap, elem, foldl, foldr1, notElem, or, mapM, sequence, id, (.)) import System.Environment as Exports import System.Exit as Exports import System.IO as Exports (Handle, hClose) import System.IO.Error as Exports import System.IO.Unsafe as Exports import System.Mem as Exports import System.Mem.StableName as Exports import System.Timeout as Exports import Text.ParserCombinators.ReadP as Exports (ReadP, ReadS, readP_to_S, readS_to_P) import Text.ParserCombinators.ReadPrec as Exports (ReadPrec, readPrec_to_P, readP_to_Prec, readPrec_to_S, readS_to_Prec) import Text.Printf as Exports (printf, hPrintf) import Text.Read as Exports (Read(..), readMaybe, readEither) import Unsafe.Coerce as Exports -- Conditional imports for reimplementations #if MIN_VERSION_base(4,7,0) import Data.Bool (bool) import Debug.Trace (traceShowId, traceM, traceShowM) import Data.Functor (($>)) #endif #if MIN_VERSION_base(4,8,0) import Data.Function ((&)) import Data.List (isSubsequenceOf, sortOn, uncons) #endif --------------------------------- -- Reimplementations for base-4.7 --------------------------------- #if !MIN_VERSION_base(4,7,0) -- | Case analysis for the 'Bool' type. -- @bool a b p@ evaluates to @a@ when @p@ is @False@, and evaluates to @b@ -- when @p@ is @True@. bool :: a -> a -> Bool -> a bool f t b = if b then t else f {-| Like 'traceShow' but returns the shown value instead of a third value. -} traceShowId :: (Show a) => a -> a traceShowId a = trace (show a) a {-| Like 'trace' but returning unit in an arbitrary monad. Allows for convenient use in do-notation. Note that the application of 'trace' is not an action in the monad, as 'traceIO' is in the 'IO' monad. > ... = do > x <- ... > traceM $ "x: " ++ show x > y <- ... > traceM $ "y: " ++ show y -} traceM :: (Monad m) => String -> m () traceM string = trace string $ return () {-| Like 'traceM', but uses 'show' on the argument to convert it to a 'String'. > ... = do > x <- ... > traceShowM $ x > y <- ... > traceShowM $ x + y -} traceShowM :: (Show a, Monad m) => a -> m () traceShowM = traceM . show infixl 4 $> -- | Flipped version of '<$'. ($>) :: Functor f => f a -> b -> f b ($>) = flip (<$) #endif --------------------------------- -- Reimplementations for base-4.8 --------------------------------- #if !MIN_VERSION_base(4,8,0) infixl 1 & -- | '&' is a reverse application operator. This provides notational -- convenience. Its precedence is one higher than that of the forward -- application operator '$', which allows '&' to be nested in '$'. (&) :: a -> (a -> b) -> b x & f = f x -- | The 'isSubsequenceOf' function takes two lists and returns 'True' if the -- first list is a subsequence of the second list. -- -- @'isSubsequenceOf' x y@ is equivalent to @'elem' x ('subsequences' y)@. -- -- ==== __Examples__ -- -- >>> isSubsequenceOf "GHC" "The Glorious Haskell Compiler" -- True -- >>> isSubsequenceOf ['a','d'..'z'] ['a'..'z'] -- True -- >>> isSubsequenceOf [1..10] [10,9..0] -- False isSubsequenceOf :: (Eq a) => [a] -> [a] -> Bool isSubsequenceOf [] _ = True isSubsequenceOf _ [] = False isSubsequenceOf a@(x:a') (y:b) | x == y = isSubsequenceOf a' b | otherwise = isSubsequenceOf a b -- | Decompose a list into its head and tail. If the list is empty, -- returns 'Nothing'. If the list is non-empty, returns @'Just' (x, xs)@, -- where @x@ is the head of the list and @xs@ its tail. uncons :: [a] -> Maybe (a, [a]) uncons [] = Nothing uncons (x:xs) = Just (x, xs) -- | Sort a list by comparing the results of a key function applied to each -- element. @sortOn f@ is equivalent to @sortBy . comparing f@, but has the -- performance advantage of only evaluating @f@ once for each element in the -- input list. This is called the decorate-sort-undecorate paradigm, or -- Schwartzian transform. sortOn :: Ord b => (a -> b) -> [a] -> [a] sortOn f = map snd . sortBy (comparing fst) . map (\x -> let y = f x in y `seq` (y, x)) #endif