%
% (c) The University of Glasgow 2006
% (c) The University of Glasgow 1992-2002
%
\begin{code}
module Util (
ghciSupported, debugIsOn, ghciTablesNextToCode, isDynamicGhcLib,
isWindowsHost, isWindowsTarget, isDarwinTarget,
zipEqual, zipWithEqual, zipWith3Equal, zipWith4Equal,
zipLazy, stretchZipWith,
unzipWith,
mapFst, mapSnd,
mapAndUnzip, mapAndUnzip3,
nOfThem, filterOut, partitionWith, splitEithers,
foldl1', foldl2, count, all2,
lengthExceeds, lengthIs, lengthAtLeast,
listLengthCmp, atLength, equalLength, compareLength,
isSingleton, only, singleton,
notNull, snocView,
isIn, isn'tIn,
fstOf3, sndOf3, thirdOf3,
takeList, dropList, splitAtList, split,
dropTail,
nTimes,
sortLe, sortWith, on,
isEqual, eqListBy,
thenCmp, cmpList,
removeSpaces,
fuzzyMatch,
transitiveClosure,
seqList,
looksLikeModuleName,
getCmd, toCmdArgs, toArgs,
readRational,
createDirectoryHierarchy,
doesDirNameExist,
modificationTimeIfExists,
global, consIORef, globalMVar, globalEmptyMVar,
Suffix,
splitLongestPrefix,
escapeSpaces,
parseSearchPath,
Direction(..), reslash,
abstractConstr, abstractDataType, mkNoRepType
) where
#include "HsVersions.h"
import Panic
import Data.Data
import Data.IORef ( IORef, newIORef, atomicModifyIORef )
import System.IO.Unsafe ( unsafePerformIO )
import Data.List hiding (group)
import Control.Concurrent.MVar ( MVar, newMVar, newEmptyMVar )
#ifdef DEBUG
import FastTypes
#endif
import Control.Monad ( unless )
import System.IO.Error as IO ( catch, isDoesNotExistError )
import System.Directory ( doesDirectoryExist, createDirectory,
getModificationTime )
import System.FilePath
import System.Time ( ClockTime )
import Data.Char ( isUpper, isAlphaNum, isSpace, ord, isDigit )
import Data.Ratio ( (%) )
import Data.Ord ( comparing )
import Data.Bits
import Data.Word
import qualified Data.IntMap as IM
infixr 9 `thenCmp`
\end{code}
%************************************************************************
%* *
\subsection{Is DEBUG on, are we on Windows, etc?}
%* *
%************************************************************************
These booleans are global constants, set by CPP flags. They allow us to
recompile a single module (this one) to change whether or not debug output
appears. They sometimes let us avoid even running CPP elsewhere.
It's important that the flags are literal constants (True/False). Then,
with -0, tests of the flags in other modules will simplify to the correct
branch of the conditional, thereby dropping debug code altogether when
the flags are off.
\begin{code}
ghciSupported :: Bool
#ifdef GHCI
ghciSupported = True
#else
ghciSupported = False
#endif
debugIsOn :: Bool
#ifdef DEBUG
debugIsOn = True
#else
debugIsOn = False
#endif
ghciTablesNextToCode :: Bool
#ifdef GHCI_TABLES_NEXT_TO_CODE
ghciTablesNextToCode = True
#else
ghciTablesNextToCode = False
#endif
isDynamicGhcLib :: Bool
#ifdef DYNAMIC
isDynamicGhcLib = True
#else
isDynamicGhcLib = False
#endif
isWindowsHost :: Bool
#ifdef mingw32_HOST_OS
isWindowsHost = True
#else
isWindowsHost = False
#endif
isWindowsTarget :: Bool
#ifdef mingw32_TARGET_OS
isWindowsTarget = True
#else
isWindowsTarget = False
#endif
isDarwinTarget :: Bool
#ifdef darwin_TARGET_OS
isDarwinTarget = True
#else
isDarwinTarget = False
#endif
\end{code}
%************************************************************************
%* *
\subsection{A for loop}
%* *
%************************************************************************
\begin{code}
nTimes :: Int -> (a -> a) -> (a -> a)
nTimes 0 _ = id
nTimes 1 f = f
nTimes n f = f . nTimes (n1) f
\end{code}
\begin{code}
fstOf3 :: (a,b,c) -> a
sndOf3 :: (a,b,c) -> b
thirdOf3 :: (a,b,c) -> c
fstOf3 (a,_,_) = a
sndOf3 (_,b,_) = b
thirdOf3 (_,_,c) = c
\end{code}
%************************************************************************
%* *
\subsection[Utils-lists]{General list processing}
%* *
%************************************************************************
\begin{code}
filterOut :: (a->Bool) -> [a] -> [a]
filterOut _ [] = []
filterOut p (x:xs) | p x = filterOut p xs
| otherwise = x : filterOut p xs
partitionWith :: (a -> Either b c) -> [a] -> ([b], [c])
partitionWith _ [] = ([],[])
partitionWith f (x:xs) = case f x of
Left b -> (b:bs, cs)
Right c -> (bs, c:cs)
where (bs,cs) = partitionWith f xs
splitEithers :: [Either a b] -> ([a], [b])
splitEithers [] = ([],[])
splitEithers (e : es) = case e of
Left x -> (x:xs, ys)
Right y -> (xs, y:ys)
where (xs,ys) = splitEithers es
\end{code}
A paranoid @zip@ (and some @zipWith@ friends) that checks the lists
are of equal length. Alastair Reid thinks this should only happen if
DEBUGging on; hey, why not?
\begin{code}
zipEqual :: String -> [a] -> [b] -> [(a,b)]
zipWithEqual :: String -> (a->b->c) -> [a]->[b]->[c]
zipWith3Equal :: String -> (a->b->c->d) -> [a]->[b]->[c]->[d]
zipWith4Equal :: String -> (a->b->c->d->e) -> [a]->[b]->[c]->[d]->[e]
#ifndef DEBUG
zipEqual _ = zip
zipWithEqual _ = zipWith
zipWith3Equal _ = zipWith3
zipWith4Equal _ = zipWith4
#else
zipEqual _ [] [] = []
zipEqual msg (a:as) (b:bs) = (a,b) : zipEqual msg as bs
zipEqual msg _ _ = panic ("zipEqual: unequal lists:"++msg)
zipWithEqual msg z (a:as) (b:bs)= z a b : zipWithEqual msg z as bs
zipWithEqual _ _ [] [] = []
zipWithEqual msg _ _ _ = panic ("zipWithEqual: unequal lists:"++msg)
zipWith3Equal msg z (a:as) (b:bs) (c:cs)
= z a b c : zipWith3Equal msg z as bs cs
zipWith3Equal _ _ [] [] [] = []
zipWith3Equal msg _ _ _ _ = panic ("zipWith3Equal: unequal lists:"++msg)
zipWith4Equal msg z (a:as) (b:bs) (c:cs) (d:ds)
= z a b c d : zipWith4Equal msg z as bs cs ds
zipWith4Equal _ _ [] [] [] [] = []
zipWith4Equal msg _ _ _ _ _ = panic ("zipWith4Equal: unequal lists:"++msg)
#endif
\end{code}
\begin{code}
zipLazy :: [a] -> [b] -> [(a,b)]
zipLazy [] _ = []
zipLazy (x:xs) zs = let y : ys = zs
in (x,y) : zipLazy xs ys
\end{code}
\begin{code}
stretchZipWith :: (a -> Bool) -> b -> (a->b->c) -> [a] -> [b] -> [c]
stretchZipWith _ _ _ [] _ = []
stretchZipWith p z f (x:xs) ys
| p x = f x z : stretchZipWith p z f xs ys
| otherwise = case ys of
[] -> []
(y:ys) -> f x y : stretchZipWith p z f xs ys
\end{code}
\begin{code}
mapFst :: (a->c) -> [(a,b)] -> [(c,b)]
mapSnd :: (b->c) -> [(a,b)] -> [(a,c)]
mapFst f xys = [(f x, y) | (x,y) <- xys]
mapSnd f xys = [(x, f y) | (x,y) <- xys]
mapAndUnzip :: (a -> (b, c)) -> [a] -> ([b], [c])
mapAndUnzip _ [] = ([], [])
mapAndUnzip f (x:xs)
= let (r1, r2) = f x
(rs1, rs2) = mapAndUnzip f xs
in
(r1:rs1, r2:rs2)
mapAndUnzip3 :: (a -> (b, c, d)) -> [a] -> ([b], [c], [d])
mapAndUnzip3 _ [] = ([], [], [])
mapAndUnzip3 f (x:xs)
= let (r1, r2, r3) = f x
(rs1, rs2, rs3) = mapAndUnzip3 f xs
in
(r1:rs1, r2:rs2, r3:rs3)
\end{code}
\begin{code}
nOfThem :: Int -> a -> [a]
nOfThem n thing = replicate n thing
atLength :: ([a] -> b)
-> (Int -> b)
-> [a]
-> Int
-> b
atLength atLenPred atEndPred ls n
| n < 0 = atEndPred n
| otherwise = go n ls
where
go n [] = atEndPred n
go 0 ls = atLenPred ls
go n (_:xs) = go (n1) xs
lengthExceeds :: [a] -> Int -> Bool
lengthExceeds = atLength notNull (const False)
lengthAtLeast :: [a] -> Int -> Bool
lengthAtLeast = atLength notNull (== 0)
lengthIs :: [a] -> Int -> Bool
lengthIs = atLength null (==0)
listLengthCmp :: [a] -> Int -> Ordering
listLengthCmp = atLength atLen atEnd
where
atEnd 0 = EQ
atEnd x
| x > 0 = LT
| otherwise = GT
atLen [] = EQ
atLen _ = GT
equalLength :: [a] -> [b] -> Bool
equalLength [] [] = True
equalLength (_:xs) (_:ys) = equalLength xs ys
equalLength _ _ = False
compareLength :: [a] -> [b] -> Ordering
compareLength [] [] = EQ
compareLength (_:xs) (_:ys) = compareLength xs ys
compareLength [] _ = LT
compareLength _ [] = GT
singleton :: a -> [a]
singleton x = [x]
isSingleton :: [a] -> Bool
isSingleton [_] = True
isSingleton _ = False
notNull :: [a] -> Bool
notNull [] = False
notNull _ = True
only :: [a] -> a
#ifdef DEBUG
only [a] = a
#else
only (a:_) = a
#endif
only _ = panic "Util: only"
\end{code}
Debugging/specialising versions of \tr{elem} and \tr{notElem}
\begin{code}
isIn, isn'tIn :: Eq a => String -> a -> [a] -> Bool
# ifndef DEBUG
isIn _msg x ys = x `elem` ys
isn'tIn _msg x ys = x `notElem` ys
# else /* DEBUG */
isIn msg x ys
= elem100 (_ILIT(0)) x ys
where
elem100 _ _ [] = False
elem100 i x (y:ys)
| i ># _ILIT(100) = trace ("Over-long elem in " ++ msg)
(x `elem` (y:ys))
| otherwise = x == y || elem100 (i +# _ILIT(1)) x ys
isn'tIn msg x ys
= notElem100 (_ILIT(0)) x ys
where
notElem100 _ _ [] = True
notElem100 i x (y:ys)
| i ># _ILIT(100) = trace ("Over-long notElem in " ++ msg)
(x `notElem` (y:ys))
| otherwise = x /= y && notElem100 (i +# _ILIT(1)) x ys
# endif /* DEBUG */
\end{code}
%************************************************************************
%* *
\subsubsection[Utils-Carsten-mergesort]{A mergesort from Carsten}
%* *
%************************************************************************
\begin{display}
Date: Mon, 3 May 93 20:45:23 +0200
From: Carsten Kehler Holst
To: partain@dcs.gla.ac.uk
Subject: natural merge sort beats quick sort [ and it is prettier ]
Here is a piece of Haskell code that I'm rather fond of. See it as an
attempt to get rid of the ridiculous quick-sort routine. group is
quite useful by itself I think it was John's idea originally though I
believe the lazy version is due to me [surprisingly complicated].
gamma [used to be called] is called gamma because I got inspired by
the Gamma calculus. It is not very close to the calculus but does
behave less sequentially than both foldr and foldl. One could imagine
a version of gamma that took a unit element as well thereby avoiding
the problem with empty lists.
I've tried this code against
1) insertion sort - as provided by haskell
2) the normal implementation of quick sort
3) a deforested version of quick sort due to Jan Sparud
4) a super-optimized-quick-sort of Lennart's
If the list is partially sorted both merge sort and in particular
natural merge sort wins. If the list is random [ average length of
rising subsequences = approx 2 ] mergesort still wins and natural
merge sort is marginally beaten by Lennart's soqs. The space
consumption of merge sort is a bit worse than Lennart's quick sort
approx a factor of 2. And a lot worse if Sparud's bug-fix [see his
fpca article ] isn't used because of group.
have fun
Carsten
\end{display}
\begin{code}
group :: (a -> a -> Bool) -> [a] -> [[a]]
group _ [] = []
group p (x:xs) = group' xs x x (x :)
where
group' [] _ _ s = [s []]
group' (x:xs) x_min x_max s
| x_max `p` x = group' xs x_min x (s . (x :))
| not (x_min `p` x) = group' xs x x_max ((x :) . s)
| otherwise = s [] : group' xs x x (x :)
generalMerge :: (a -> a -> Bool) -> [a] -> [a] -> [a]
generalMerge _ xs [] = xs
generalMerge _ [] ys = ys
generalMerge p (x:xs) (y:ys) | x `p` y = x : generalMerge p xs (y:ys)
| otherwise = y : generalMerge p (x:xs) ys
balancedFold :: (a -> a -> a) -> [a] -> a
balancedFold _ [] = error "can't reduce an empty list using balancedFold"
balancedFold _ [x] = x
balancedFold f l = balancedFold f (balancedFold' f l)
balancedFold' :: (a -> a -> a) -> [a] -> [a]
balancedFold' f (x:y:xs) = f x y : balancedFold' f xs
balancedFold' _ xs = xs
generalNaturalMergeSort :: (a -> a -> Bool) -> [a] -> [a]
generalNaturalMergeSort _ [] = []
generalNaturalMergeSort p xs = (balancedFold (generalMerge p) . group p) xs
#if NOT_USED
generalMergeSort p [] = []
generalMergeSort p xs = (balancedFold (generalMerge p) . map (: [])) xs
mergeSort, naturalMergeSort :: Ord a => [a] -> [a]
mergeSort = generalMergeSort (<=)
naturalMergeSort = generalNaturalMergeSort (<=)
mergeSortLe le = generalMergeSort le
#endif
sortLe :: (a->a->Bool) -> [a] -> [a]
sortLe le = generalNaturalMergeSort le
sortWith :: Ord b => (a->b) -> [a] -> [a]
sortWith get_key xs = sortLe le xs
where
x `le` y = get_key x < get_key y
on :: (a -> a -> c) -> (b -> a) -> b -> b -> c
on cmp sel = \x y -> sel x `cmp` sel y
\end{code}
%************************************************************************
%* *
\subsection[Utils-transitive-closure]{Transitive closure}
%* *
%************************************************************************
This algorithm for transitive closure is straightforward, albeit quadratic.
\begin{code}
transitiveClosure :: (a -> [a])
-> (a -> a -> Bool)
-> [a]
-> [a]
transitiveClosure succ eq xs
= go [] xs
where
go done [] = done
go done (x:xs) | x `is_in` done = go done xs
| otherwise = go (x:done) (succ x ++ xs)
_ `is_in` [] = False
x `is_in` (y:ys) | eq x y = True
| otherwise = x `is_in` ys
\end{code}
%************************************************************************
%* *
\subsection[Utils-accum]{Accumulating}
%* *
%************************************************************************
A combination of foldl with zip. It works with equal length lists.
\begin{code}
foldl2 :: (acc -> a -> b -> acc) -> acc -> [a] -> [b] -> acc
foldl2 _ z [] [] = z
foldl2 k z (a:as) (b:bs) = foldl2 k (k z a b) as bs
foldl2 _ _ _ _ = panic "Util: foldl2"
all2 :: (a -> b -> Bool) -> [a] -> [b] -> Bool
all2 _ [] [] = True
all2 p (x:xs) (y:ys) = p x y && all2 p xs ys
all2 _ _ _ = False
\end{code}
Count the number of times a predicate is true
\begin{code}
count :: (a -> Bool) -> [a] -> Int
count _ [] = 0
count p (x:xs) | p x = 1 + count p xs
| otherwise = count p xs
\end{code}
@splitAt@, @take@, and @drop@ but with length of another
list giving the break-off point:
\begin{code}
takeList :: [b] -> [a] -> [a]
takeList [] _ = []
takeList (_:xs) ls =
case ls of
[] -> []
(y:ys) -> y : takeList xs ys
dropList :: [b] -> [a] -> [a]
dropList [] xs = xs
dropList _ xs@[] = xs
dropList (_:xs) (_:ys) = dropList xs ys
splitAtList :: [b] -> [a] -> ([a], [a])
splitAtList [] xs = ([], xs)
splitAtList _ xs@[] = (xs, xs)
splitAtList (_:xs) (y:ys) = (y:ys', ys'')
where
(ys', ys'') = splitAtList xs ys
dropTail :: Int -> [a] -> [a]
dropTail n = reverse . drop n . reverse
snocView :: [a] -> Maybe ([a],a)
snocView [] = Nothing
snocView xs = go [] xs
where
go acc [x] = Just (reverse acc, x)
go acc (x:xs) = go (x:acc) xs
go _ [] = panic "Util: snocView"
split :: Char -> String -> [String]
split c s = case rest of
[] -> [chunk]
_:rest -> chunk : split c rest
where (chunk, rest) = break (==c) s
\end{code}
%************************************************************************
%* *
\subsection[Utils-comparison]{Comparisons}
%* *
%************************************************************************
\begin{code}
isEqual :: Ordering -> Bool
isEqual GT = False
isEqual EQ = True
isEqual LT = False
thenCmp :: Ordering -> Ordering -> Ordering
thenCmp EQ ordering = ordering
thenCmp ordering _ = ordering
eqListBy :: (a->a->Bool) -> [a] -> [a] -> Bool
eqListBy _ [] [] = True
eqListBy eq (x:xs) (y:ys) = eq x y && eqListBy eq xs ys
eqListBy _ _ _ = False
cmpList :: (a -> a -> Ordering) -> [a] -> [a] -> Ordering
cmpList _ [] [] = EQ
cmpList _ [] _ = LT
cmpList _ _ [] = GT
cmpList cmp (a:as) (b:bs)
= case cmp a b of { EQ -> cmpList cmp as bs; xxx -> xxx }
\end{code}
\begin{code}
removeSpaces :: String -> String
removeSpaces = reverse . dropWhile isSpace . reverse . dropWhile isSpace
\end{code}
%************************************************************************
%* *
\subsection{Edit distance}
%* *
%************************************************************************
\begin{code}
restrictedDamerauLevenshteinDistance :: String -> String -> Int
restrictedDamerauLevenshteinDistance str1 str2 = restrictedDamerauLevenshteinDistanceWithLengths m n str1 str2
where
m = length str1
n = length str2
restrictedDamerauLevenshteinDistanceWithLengths :: Int -> Int -> String -> String -> Int
restrictedDamerauLevenshteinDistanceWithLengths m n str1 str2
| m <= n = if n <= 32
then restrictedDamerauLevenshteinDistance' (undefined :: Word32) m n str1 str2
else restrictedDamerauLevenshteinDistance' (undefined :: Integer) m n str1 str2
| otherwise = if m <= 32
then restrictedDamerauLevenshteinDistance' (undefined :: Word32) n m str2 str1
else restrictedDamerauLevenshteinDistance' (undefined :: Integer) n m str2 str1
restrictedDamerauLevenshteinDistance' :: (Bits bv) => bv -> Int -> Int -> String -> String -> Int
restrictedDamerauLevenshteinDistance' _bv_dummy m n str1 str2
| [] <- str1 = n
| otherwise = extractAnswer $ foldl' (restrictedDamerauLevenshteinDistanceWorker (matchVectors str1) top_bit_mask vector_mask) (0, 0, m_ones, 0, m) str2
where m_ones@vector_mask = (2 ^ m) 1
top_bit_mask = (1 `shiftL` (m 1)) `asTypeOf` _bv_dummy
extractAnswer (_, _, _, _, distance) = distance
restrictedDamerauLevenshteinDistanceWorker :: (Bits bv) => IM.IntMap bv -> bv -> bv -> (bv, bv, bv, bv, Int) -> Char -> (bv, bv, bv, bv, Int)
restrictedDamerauLevenshteinDistanceWorker str1_mvs top_bit_mask vector_mask (pm, d0, vp, vn, distance) char2
= seq str1_mvs $ seq top_bit_mask $ seq vector_mask $ seq pm' $ seq d0' $ seq vp' $ seq vn' $ seq distance'' $ seq char2 $ (pm', d0', vp', vn', distance'')
where
pm' = IM.findWithDefault 0 (ord char2) str1_mvs
d0' = ((((sizedComplement vector_mask d0) .&. pm') `shiftL` 1) .&. pm)
.|. ((((pm' .&. vp) + vp) .&. vector_mask) `xor` vp) .|. pm' .|. vn
hp' = vn .|. sizedComplement vector_mask (d0' .|. vp)
hn' = d0' .&. vp
hp'_shift = ((hp' `shiftL` 1) .|. 1) .&. vector_mask
hn'_shift = (hn' `shiftL` 1) .&. vector_mask
vp' = hn'_shift .|. sizedComplement vector_mask (d0' .|. hp'_shift)
vn' = d0' .&. hp'_shift
distance' = if hp' .&. top_bit_mask /= 0 then distance + 1 else distance
distance'' = if hn' .&. top_bit_mask /= 0 then distance' 1 else distance'
sizedComplement :: Bits bv => bv -> bv -> bv
sizedComplement vector_mask vect = vector_mask `xor` vect
matchVectors :: Bits bv => String -> IM.IntMap bv
matchVectors = snd . foldl' go (0 :: Int, IM.empty)
where
go (ix, im) char = let ix' = ix + 1
im' = IM.insertWith (.|.) (ord char) (2 ^ ix) im
in seq ix' $ seq im' $ (ix', im')
#ifdef __GLASGOW_HASKELL__
#endif
fuzzyMatch :: String -> [String] -> [String]
fuzzyMatch user_entered possibilites = map fst $ take mAX_RESULTS $ sortBy (comparing snd)
[ (poss, distance) | poss <- possibilites
, let distance = restrictedDamerauLevenshteinDistance poss user_entered
, distance <= fuzzy_threshold ]
where
fuzzy_threshold = max (round $ fromInteger (genericLength user_entered) / (4 :: Rational)) 1
mAX_RESULTS = 3
\end{code}
%************************************************************************
%* *
\subsection[Utils-pairs]{Pairs}
%* *
%************************************************************************
\begin{code}
unzipWith :: (a -> b -> c) -> [(a, b)] -> [c]
unzipWith f pairs = map ( \ (a, b) -> f a b ) pairs
\end{code}
\begin{code}
seqList :: [a] -> b -> b
seqList [] b = b
seqList (x:xs) b = x `seq` seqList xs b
\end{code}
Global variables:
\begin{code}
global :: a -> IORef a
global a = unsafePerformIO (newIORef a)
\end{code}
\begin{code}
consIORef :: IORef [a] -> a -> IO ()
consIORef var x = do
atomicModifyIORef var (\xs -> (x:xs,()))
\end{code}
\begin{code}
globalMVar :: a -> MVar a
globalMVar a = unsafePerformIO (newMVar a)
globalEmptyMVar :: MVar a
globalEmptyMVar = unsafePerformIO newEmptyMVar
\end{code}
Module names:
\begin{code}
looksLikeModuleName :: String -> Bool
looksLikeModuleName [] = False
looksLikeModuleName (c:cs) = isUpper c && go cs
where go [] = True
go ('.':cs) = looksLikeModuleName cs
go (c:cs) = (isAlphaNum c || c == '_' || c == '\'') && go cs
\end{code}
Akin to @Prelude.words@, but acts like the Bourne shell, treating
quoted strings as Haskell Strings, and also parses Haskell [String]
syntax.
\begin{code}
getCmd :: String -> Either String
(String, String)
getCmd s = case break isSpace $ dropWhile isSpace s of
([], _) -> Left ("Couldn't find command in " ++ show s)
res -> Right res
toCmdArgs :: String -> Either String
(String, [String])
toCmdArgs s = case getCmd s of
Left err -> Left err
Right (cmd, s') -> case toArgs s' of
Left err -> Left err
Right args -> Right (cmd, args)
toArgs :: String -> Either String
[String]
toArgs str
= case dropWhile isSpace str of
s@('[':_) -> case reads s of
[(args, spaces)]
| all isSpace spaces ->
Right args
_ ->
Left ("Couldn't read " ++ show str ++ "as [String]")
s -> toArgs' s
where
toArgs' s = case dropWhile isSpace s of
[] -> Right []
('"' : _) -> case reads s of
[(arg, rest)]
| all isSpace (take 1 rest) ->
case toArgs' rest of
Left err -> Left err
Right args -> Right (arg : args)
_ ->
Left ("Couldn't read " ++ show s ++ "as String")
s' -> case break isSpace s' of
(arg, s'') -> case toArgs' s'' of
Left err -> Left err
Right args -> Right (arg : args)
\end{code}
-- -----------------------------------------------------------------------------
-- Floats
\begin{code}
readRational__ :: ReadS Rational
readRational__ r = do
(n,d,s) <- readFix r
(k,t) <- readExp s
return ((n%1)*10^^(kd), t)
where
readFix r = do
(ds,s) <- lexDecDigits r
(ds',t) <- lexDotDigits s
return (read (ds++ds'), length ds', t)
readExp (e:s) | e `elem` "eE" = readExp' s
readExp s = return (0,s)
readExp' ('+':s) = readDec s
readExp' ('-':s) = do (k,t) <- readDec s
return (k,t)
readExp' s = readDec s
readDec s = do
(ds,r) <- nonnull isDigit s
return (foldl1 (\n d -> n * 10 + d) [ ord d ord '0' | d <- ds ],
r)
lexDecDigits = nonnull isDigit
lexDotDigits ('.':s) = return (span isDigit s)
lexDotDigits s = return ("",s)
nonnull p s = do (cs@(_:_),t) <- return (span p s)
return (cs,t)
readRational :: String -> Rational
readRational top_s
= case top_s of
'-' : xs -> (read_me xs)
xs -> read_me xs
where
read_me s
= case (do { (x,"") <- readRational__ s ; return x }) of
[x] -> x
[] -> error ("readRational: no parse:" ++ top_s)
_ -> error ("readRational: ambiguous parse:" ++ top_s)
createDirectoryHierarchy :: FilePath -> IO ()
createDirectoryHierarchy dir | isDrive dir = return ()
createDirectoryHierarchy dir = do
b <- doesDirectoryExist dir
unless b $ do createDirectoryHierarchy (takeDirectory dir)
createDirectory dir
doesDirNameExist :: FilePath -> IO Bool
doesDirNameExist fpath = case takeDirectory fpath of
"" -> return True
_ -> doesDirectoryExist (takeDirectory fpath)
modificationTimeIfExists :: FilePath -> IO (Maybe ClockTime)
modificationTimeIfExists f = do
(do t <- getModificationTime f; return (Just t))
`IO.catch` \e -> if isDoesNotExistError e
then return Nothing
else ioError e
splitLongestPrefix :: String -> (Char -> Bool) -> (String,String)
splitLongestPrefix str pred
| null r_pre = (str, [])
| otherwise = (reverse (tail r_pre), reverse r_suf)
where (r_suf, r_pre) = break pred (reverse str)
escapeSpaces :: String -> String
escapeSpaces = foldr (\c s -> if isSpace c then '\\':c:s else c:s) ""
type Suffix = String
parseSearchPath :: String -> [FilePath]
parseSearchPath path = split path
where
split :: String -> [String]
split s =
case rest' of
[] -> [chunk]
_:rest -> chunk : split rest
where
chunk =
case chunk' of
#ifdef mingw32_HOST_OS
('\"':xs@(_:_)) | last xs == '\"' -> init xs
#endif
_ -> chunk'
(chunk', rest') = break isSearchPathSeparator s
data Direction = Forwards | Backwards
reslash :: Direction -> FilePath -> FilePath
reslash d = f
where f ('/' : xs) = slash : f xs
f ('\\' : xs) = slash : f xs
f (x : xs) = x : f xs
f "" = ""
slash = case d of
Forwards -> '/'
Backwards -> '\\'
\end{code}
%************************************************************************
%* *
\subsection[Utils-Data]{Utils for defining Data instances}
%* *
%************************************************************************
These functions helps us to define Data instances for abstract types.
\begin{code}
abstractConstr :: String -> Constr
abstractConstr n = mkConstr (abstractDataType n) ("{abstract:"++n++"}") [] Prefix
\end{code}
\begin{code}
abstractDataType :: String -> DataType
abstractDataType n = mkDataType n [abstractConstr n]
\end{code}
\begin{code}
#if __GLASGOW_HASKELL__ < 612
mkNoRepType :: String -> DataType
mkNoRepType = mkNorepType
#endif
\end{code}