+++ /dev/null
-%
-% (c) The University of Glasgow 1992-2002
-%
-\section[Util]{Highly random utility functions}
-
-\begin{code}
-module Util (
-
- -- general list processing
- zipEqual, zipWithEqual, zipWith3Equal, zipWith4Equal,
- zipLazy, stretchZipWith,
- mapFst, mapSnd,
- mapAndUnzip, mapAndUnzip3,
- nOfThem, filterOut,
- lengthExceeds, lengthIs, lengthAtLeast, listLengthCmp, atLength,
- isSingleton, only, singleton,
- notNull, snocView,
-
- isIn, isn'tIn,
-
- -- for-loop
- nTimes,
-
- -- sorting
- sortLe, sortWith,
-
- -- transitive closures
- transitiveClosure,
-
- -- accumulating
- mapAccumL, mapAccumR, mapAccumB,
- foldl2, count, all2,
-
- takeList, dropList, splitAtList, split,
-
- -- comparisons
- isEqual, eqListBy, equalLength, compareLength,
- thenCmp, cmpList, prefixMatch, suffixMatch, maybePrefixMatch,
- removeSpaces,
-
- -- strictness
- foldl', seqList,
-
- -- pairs
- unzipWith,
-
- global, consIORef,
-
- -- module names
- looksLikeModuleName,
-
- toArgs,
-
- -- Floating point stuff
- readRational,
-
- -- IO-ish utilities
- createDirectoryHierarchy,
- doesDirNameExist,
- modificationTimeIfExists,
-
- later, handleDyn, handle,
-
- -- Filename utils
- Suffix,
- splitFilename, suffixOf, basenameOf, joinFileExt,
- splitFilenameDir, joinFileName,
- splitFilename3,
- splitLongestPrefix,
- replaceFilenameSuffix, directoryOf, filenameOf,
- replaceFilenameDirectory,
- escapeSpaces, isPathSeparator,
- parseSearchPath,
- normalisePath, platformPath, pgmPath,
- ) where
-
-#include "HsVersions.h"
-
-import Panic ( panic, trace )
-import FastTypes
-
-import EXCEPTION ( Exception(..), finally, throwDyn, catchDyn, throw )
-import qualified EXCEPTION as Exception
-import DYNAMIC ( Typeable )
-import DATA_IOREF ( IORef, newIORef )
-import UNSAFE_IO ( unsafePerformIO )
-import DATA_IOREF ( readIORef, writeIORef )
-
-import qualified List ( elem, notElem )
-
-#ifndef DEBUG
-import List ( zipWith4 )
-#endif
-
-import Monad ( when )
-import IO ( catch, isDoesNotExistError )
-import Directory ( doesDirectoryExist, createDirectory )
-import Char ( isUpper, isAlphaNum, isSpace, ord, isDigit )
-import Ratio ( (%) )
-import Time ( ClockTime )
-import Directory ( getModificationTime )
-
-infixr 9 `thenCmp`
-\end{code}
-
-%************************************************************************
-%* *
-\subsection{The Eager monad}
-%* *
-%************************************************************************
-
-The @Eager@ monad is just an encoding of continuation-passing style,
-used to allow you to express "do this and then that", mainly to avoid
-space leaks. It's done with a type synonym to save bureaucracy.
-
-\begin{code}
-#if NOT_USED
-
-type Eager ans a = (a -> ans) -> ans
-
-runEager :: Eager a a -> a
-runEager m = m (\x -> x)
-
-appEager :: Eager ans a -> (a -> ans) -> ans
-appEager m cont = m cont
-
-thenEager :: Eager ans a -> (a -> Eager ans b) -> Eager ans b
-thenEager m k cont = m (\r -> k r cont)
-
-returnEager :: a -> Eager ans a
-returnEager v cont = cont v
-
-mapEager :: (a -> Eager ans b) -> [a] -> Eager ans [b]
-mapEager f [] = returnEager []
-mapEager f (x:xs) = f x `thenEager` \ y ->
- mapEager f xs `thenEager` \ ys ->
- returnEager (y:ys)
-#endif
-\end{code}
-
-%************************************************************************
-%* *
-\subsection{A for loop}
-%* *
-%************************************************************************
-
-\begin{code}
--- Compose a function with itself n times. (nth rather than twice)
-nTimes :: Int -> (a -> a) -> (a -> a)
-nTimes 0 _ = id
-nTimes 1 f = f
-nTimes n f = f . nTimes (n-1) f
-\end{code}
-
-%************************************************************************
-%* *
-\subsection[Utils-lists]{General list processing}
-%* *
-%************************************************************************
-
-\begin{code}
-filterOut :: (a->Bool) -> [a] -> [a]
--- Like filter, only reverses the sense of the test
-filterOut p [] = []
-filterOut p (x:xs) | p x = filterOut p xs
- | otherwise = x : filterOut p xs
-\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 msg [] [] = []
-zipEqual msg (a:as) (b:bs) = (a,b) : zipEqual msg as bs
-zipEqual msg as bs = panic ("zipEqual: unequal lists:"++msg)
-
-zipWithEqual msg z (a:as) (b:bs)= z a b : zipWithEqual msg z as bs
-zipWithEqual msg _ [] [] = []
-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 msg _ [] [] [] = []
-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 msg _ [] [] [] [] = []
-zipWith4Equal msg _ _ _ _ _ = panic ("zipWith4Equal: unequal lists:"++msg)
-#endif
-\end{code}
-
-\begin{code}
--- zipLazy is lazy in the second list (observe the ~)
-
-zipLazy :: [a] -> [b] -> [(a,b)]
-zipLazy [] ys = []
-zipLazy (x:xs) ~(y:ys) = (x,y) : zipLazy xs ys
-\end{code}
-
-
-\begin{code}
-stretchZipWith :: (a -> Bool) -> b -> (a->b->c) -> [a] -> [b] -> [c]
--- (stretchZipWith p z f xs ys) stretches ys by inserting z in
--- the places where p returns *True*
-
-stretchZipWith p z f [] ys = []
-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 f [] = ([],[])
-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 f [] = ([],[],[])
-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 atLen atEnd ls n' unravels list 'ls' to position 'n';
--- specification:
---
--- atLength atLenPred atEndPred ls n
--- | n < 0 = atLenPred n
--- | length ls < n = atEndPred (n - length ls)
--- | otherwise = atLenPred (drop n ls)
---
-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 (n-1) xs
-
--- special cases.
-lengthExceeds :: [a] -> Int -> Bool
--- (lengthExceeds xs n) = (length xs > n)
-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 -- not yet seen 'n' elts, so list length is < n.
- | otherwise = GT
-
- atLen [] = EQ
- atLen _ = GT
-
-singleton :: a -> [a]
-singleton x = [x]
-
-isSingleton :: [a] -> Bool
-isSingleton [x] = True
-isSingleton _ = False
-
-notNull :: [a] -> Bool
-notNull [] = False
-notNull _ = True
-
-snocView :: [a] -> Maybe ([a],a)
- -- Split off the last element
-snocView [] = Nothing
-snocView xs = go [] xs
- where
- -- Invariant: second arg is non-empty
- go acc [x] = Just (reverse acc, x)
- go acc (x:xs) = go (x:acc) xs
-
-only :: [a] -> a
-#ifdef DEBUG
-only [a] = a
-#else
-only (a:_) = a
-#endif
-\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 = elem__ x ys
-isn'tIn msg x ys = notElem__ x ys
-
---these are here to be SPECIALIZEd (automagically)
-elem__ _ [] = False
-elem__ x (y:ys) = x==y || elem__ x ys
-
-notElem__ x [] = True
-notElem__ x (y:ys) = x /= y && notElem__ x ys
-
-# else /* DEBUG */
-isIn msg x ys
- = elem (_ILIT 0) x ys
- where
- elem i _ [] = False
- elem i x (y:ys)
- | i ># _ILIT 100 = trace ("Over-long elem in " ++ msg) $
- x `List.elem` (y:ys)
- | otherwise = x == y || elem (i +# _ILIT(1)) x ys
-
-isn'tIn msg x ys
- = notElem (_ILIT 0) x ys
- where
- notElem i x [] = True
- notElem i x (y:ys)
- | i ># _ILIT 100 = trace ("Over-long notElem in " ++ msg) $
- x `List.notElem` (y:ys)
- | otherwise = x /= y && notElem (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 <kehler@cs.chalmers.se>
-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]]
--- Given a <= function, group finds maximal contiguous up-runs
--- or down-runs in the input list.
--- It's stable, in the sense that it never re-orders equal elements
---
--- Date: Mon, 12 Feb 1996 15:09:41 +0000
--- From: Andy Gill <andy@dcs.gla.ac.uk>
--- Here is a `better' definition of group.
-
-group p [] = []
-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 :)
- -- NB: the 'not' is essential for stablity
- -- x `p` x_min would reverse equal elements
-
-generalMerge :: (a -> a -> Bool) -> [a] -> [a] -> [a]
-generalMerge p xs [] = xs
-generalMerge p [] ys = ys
-generalMerge p (x:xs) (y:ys) | x `p` y = x : generalMerge p xs (y:ys)
- | otherwise = y : generalMerge p (x:xs) ys
-
--- gamma is now called balancedFold
-
-balancedFold :: (a -> a -> a) -> [a] -> a
-balancedFold f [] = error "can't reduce an empty list using balancedFold"
-balancedFold f [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' f xs = xs
-
-generalNaturalMergeSort p [] = []
-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
-\end{code}
-
-%************************************************************************
-%* *
-\subsection[Utils-transitive-closure]{Transitive closure}
-%* *
-%************************************************************************
-
-This algorithm for transitive closure is straightforward, albeit quadratic.
-
-\begin{code}
-transitiveClosure :: (a -> [a]) -- Successor function
- -> (a -> a -> Bool) -- Equality predicate
- -> [a]
- -> [a] -- The transitive closure
-
-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)
-
- x `is_in` [] = False
- x `is_in` (y:ys) | eq x y = True
- | otherwise = x `is_in` ys
-\end{code}
-
-%************************************************************************
-%* *
-\subsection[Utils-accum]{Accumulating}
-%* *
-%************************************************************************
-
-@mapAccumL@ behaves like a combination
-of @map@ and @foldl@;
-it applies a function to each element of a list, passing an accumulating
-parameter from left to right, and returning a final value of this
-accumulator together with the new list.
-
-\begin{code}
-mapAccumL :: (acc -> x -> (acc, y)) -- Function of elt of input list
- -- and accumulator, returning new
- -- accumulator and elt of result list
- -> acc -- Initial accumulator
- -> [x] -- Input list
- -> (acc, [y]) -- Final accumulator and result list
-
-mapAccumL f b [] = (b, [])
-mapAccumL f b (x:xs) = (b'', x':xs') where
- (b', x') = f b x
- (b'', xs') = mapAccumL f b' xs
-\end{code}
-
-@mapAccumR@ does the same, but working from right to left instead. Its type is
-the same as @mapAccumL@, though.
-
-\begin{code}
-mapAccumR :: (acc -> x -> (acc, y)) -- Function of elt of input list
- -- and accumulator, returning new
- -- accumulator and elt of result list
- -> acc -- Initial accumulator
- -> [x] -- Input list
- -> (acc, [y]) -- Final accumulator and result list
-
-mapAccumR f b [] = (b, [])
-mapAccumR f b (x:xs) = (b'', x':xs') where
- (b'', x') = f b' x
- (b', xs') = mapAccumR f b xs
-\end{code}
-
-Here is the bi-directional version, that works from both left and right.
-
-\begin{code}
-mapAccumB :: (accl -> accr -> x -> (accl, accr,y))
- -- Function of elt of input list
- -- and accumulator, returning new
- -- accumulator and elt of result list
- -> accl -- Initial accumulator from left
- -> accr -- Initial accumulator from right
- -> [x] -- Input list
- -> (accl, accr, [y]) -- Final accumulators and result list
-
-mapAccumB f a b [] = (a,b,[])
-mapAccumB f a b (x:xs) = (a'',b'',y:ys)
- where
- (a',b'',y) = f a b' x
- (a'',b',ys) = mapAccumB f a' b xs
-\end{code}
-
-A strict version of foldl.
-
-\begin{code}
-foldl' :: (a -> b -> a) -> a -> [b] -> a
-foldl' f z xs = lgo z xs
- where
- lgo z [] = z
- lgo z (x:xs) = (lgo $! (f z x)) xs
-\end{code}
-
-A combination of foldl with zip. It works with equal length lists.
-
-\begin{code}
-foldl2 :: (acc -> a -> b -> acc) -> acc -> [a] -> [b] -> acc
-foldl2 k z [] [] = z
-foldl2 k z (a:as) (b:bs) = foldl2 k (k z a b) as bs
-
-all2 :: (a -> b -> Bool) -> [a] -> [b] -> Bool
--- True if the lists are the same length, and
--- all corresponding elements satisfy the predicate
-all2 p [] [] = True
-all2 p (x:xs) (y:ys) = p x y && all2 p xs ys
-all2 p xs ys = False
-\end{code}
-
-Count the number of times a predicate is true
-
-\begin{code}
-count :: (a -> Bool) -> [a] -> Int
-count p [] = 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
-
-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
--- Often used in (isEqual (a `compare` b))
-isEqual GT = False
-isEqual EQ = True
-isEqual LT = False
-
-thenCmp :: Ordering -> Ordering -> Ordering
-{-# INLINE thenCmp #-}
-thenCmp EQ any = any
-thenCmp other any = other
-
-eqListBy :: (a->a->Bool) -> [a] -> [a] -> Bool
-eqListBy eq [] [] = True
-eqListBy eq (x:xs) (y:ys) = eq x y && eqListBy eq xs ys
-eqListBy eq xs ys = False
-
-equalLength :: [a] -> [b] -> Bool
-equalLength [] [] = True
-equalLength (_:xs) (_:ys) = equalLength xs ys
-equalLength xs ys = False
-
-compareLength :: [a] -> [b] -> Ordering
-compareLength [] [] = EQ
-compareLength (_:xs) (_:ys) = compareLength xs ys
-compareLength [] _ys = LT
-compareLength _xs [] = GT
-
-cmpList :: (a -> a -> Ordering) -> [a] -> [a] -> Ordering
- -- `cmpList' uses a user-specified comparer
-
-cmpList cmp [] [] = EQ
-cmpList cmp [] _ = LT
-cmpList cmp _ [] = GT
-cmpList cmp (a:as) (b:bs)
- = case cmp a b of { EQ -> cmpList cmp as bs; xxx -> xxx }
-\end{code}
-
-\begin{code}
-prefixMatch :: Eq a => [a] -> [a] -> Bool
-prefixMatch [] _str = True
-prefixMatch _pat [] = False
-prefixMatch (p:ps) (s:ss) | p == s = prefixMatch ps ss
- | otherwise = False
-
-maybePrefixMatch :: String -> String -> Maybe String
-maybePrefixMatch [] rest = Just rest
-maybePrefixMatch (_:_) [] = Nothing
-maybePrefixMatch (p:pat) (r:rest)
- | p == r = maybePrefixMatch pat rest
- | otherwise = Nothing
-
-suffixMatch :: Eq a => [a] -> [a] -> Bool
-suffixMatch pat str = prefixMatch (reverse pat) (reverse str)
-
-removeSpaces :: String -> String
-removeSpaces = reverse . dropWhile isSpace . reverse . dropWhile isSpace
-\end{code}
-
-%************************************************************************
-%* *
-\subsection[Utils-pairs]{Pairs}
-%* *
-%************************************************************************
-
-The following are curried versions of @fst@ and @snd@.
-
-\begin{code}
-#if NOT_USED
-cfst :: a -> b -> a -- stranal-sem only (Note)
-cfst x y = x
-#endif
-\end{code}
-
-The following provide us higher order functions that, when applied
-to a function, operate on pairs.
-
-\begin{code}
-#if NOT_USED
-applyToPair :: ((a -> c),(b -> d)) -> (a,b) -> (c,d)
-applyToPair (f,g) (x,y) = (f x, g y)
-
-applyToFst :: (a -> c) -> (a,b)-> (c,b)
-applyToFst f (x,y) = (f x,y)
-
-applyToSnd :: (b -> d) -> (a,b) -> (a,d)
-applyToSnd f (x,y) = (x,f y)
-#endif
-\end{code}
-
-\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
- xs <- readIORef var
- writeIORef var (x:xs)
-\end{code}
-
-Module names:
-
-\begin{code}
-looksLikeModuleName [] = False
-looksLikeModuleName (c:cs) = isUpper c && go cs
- where go [] = True
- go ('.':cs) = looksLikeModuleName cs
- go (c:cs) = (isAlphaNum c || c == '_') && go cs
-\end{code}
-
-Akin to @Prelude.words@, but sensitive to dquoted entities treating
-them as single words.
-
-\begin{code}
-toArgs :: String -> [String]
-toArgs "" = []
-toArgs s =
- case break (\ ch -> isSpace ch || ch == '"') (dropWhile isSpace s) of -- "
- (w,aft) ->
- (\ ws -> if null w then ws else w : ws) $
- case aft of
- [] -> []
- (x:xs)
- | x /= '"' -> toArgs xs
- | otherwise ->
- case lex aft of
- ((str,rs):_) -> stripQuotes str : toArgs rs
- _ -> [aft]
- where
- -- strip away dquotes; assume first and last chars contain quotes.
- stripQuotes :: String -> String
- stripQuotes ('"':xs) = init xs
- stripQuotes xs = xs
-\end{code}
-
--- -----------------------------------------------------------------------------
--- Floats
-
-\begin{code}
-readRational__ :: ReadS Rational -- NB: doesn't handle leading "-"
-readRational__ r = do
- (n,d,s) <- readFix r
- (k,t) <- readExp s
- return ((n%1)*10^^(k-d), 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 -- NB: *does* handle a leading "-"
-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)
-
-
------------------------------------------------------------------------------
--- Create a hierarchy of directories
-
-createDirectoryHierarchy :: FilePath -> IO ()
-createDirectoryHierarchy dir = do
- b <- doesDirectoryExist dir
- when (not b) $ do
- createDirectoryHierarchy (directoryOf dir)
- createDirectory dir
-
------------------------------------------------------------------------------
--- Verify that the 'dirname' portion of a FilePath exists.
---
-doesDirNameExist :: FilePath -> IO Bool
-doesDirNameExist fpath = doesDirectoryExist (directoryOf fpath)
-
--- -----------------------------------------------------------------------------
--- Exception utils
-
-later = flip finally
-
-handleDyn :: Typeable ex => (ex -> IO a) -> IO a -> IO a
-handleDyn = flip catchDyn
-
-handle :: (Exception -> IO a) -> IO a -> IO a
-#if __GLASGOW_HASKELL__ < 501
-handle = flip Exception.catchAllIO
-#else
-handle h f = f `Exception.catch` \e -> case e of
- ExitException _ -> throw e
- _ -> h e
-#endif
-
--- --------------------------------------------------------------
--- check existence & modification time at the same time
-
-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
-
--- --------------------------------------------------------------
--- Filename manipulation
-
--- Filenames are kept "normalised" inside GHC, using '/' as the path
--- separator. On Windows these functions will also recognise '\\' as
--- the path separator, but will generally construct paths using '/'.
-
-type Suffix = String
-
-splitFilename :: String -> (String,Suffix)
-splitFilename f = splitLongestPrefix f (=='.')
-
-basenameOf :: FilePath -> String
-basenameOf = fst . splitFilename
-
-suffixOf :: FilePath -> Suffix
-suffixOf = snd . splitFilename
-
-joinFileExt :: String -> String -> FilePath
-joinFileExt path "" = path
-joinFileExt path ext = path ++ '.':ext
-
--- "foo/bar/xyzzy.ext" -> ("foo/bar", "xyzzy.ext")
-splitFilenameDir :: String -> (String,String)
-splitFilenameDir str
- = let (dir, rest) = splitLongestPrefix str isPathSeparator
- (dir', rest') | null rest = (".", dir)
- | otherwise = (dir, rest)
- in (dir', rest')
-
--- "foo/bar/xyzzy.ext" -> ("foo/bar", "xyzzy", ".ext")
-splitFilename3 :: String -> (String,String,Suffix)
-splitFilename3 str
- = let (dir, rest) = splitFilenameDir str
- (name, ext) = splitFilename rest
- in (dir, name, ext)
-
-joinFileName :: String -> String -> FilePath
-joinFileName "" fname = fname
-joinFileName "." fname = fname
-joinFileName dir "" = dir
-joinFileName dir fname = dir ++ '/':fname
-
--- split a string at the last character where 'pred' is True,
--- returning a pair of strings. The first component holds the string
--- up (but not including) the last character for which 'pred' returned
--- True, the second whatever comes after (but also not including the
--- last character).
---
--- If 'pred' returns False for all characters in the string, the original
--- string is returned in the first component (and the second one is just
--- empty).
-splitLongestPrefix :: String -> (Char -> Bool) -> (String,String)
-splitLongestPrefix str pred
- | null r_pre = (str, [])
- | otherwise = (reverse (tail r_pre), reverse r_suf)
- -- 'tail' drops the char satisfying 'pred'
- where
- (r_suf, r_pre) = break pred (reverse str)
-
-replaceFilenameSuffix :: FilePath -> Suffix -> FilePath
-replaceFilenameSuffix file suf = basenameOf file `joinFileExt` suf
-
--- directoryOf strips the filename off the input string, returning
--- the directory.
-directoryOf :: FilePath -> String
-directoryOf = fst . splitFilenameDir
-
--- filenameOf strips the directory off the input string, returning
--- the filename.
-filenameOf :: FilePath -> String
-filenameOf = snd . splitFilenameDir
-
-replaceFilenameDirectory :: FilePath -> String -> FilePath
-replaceFilenameDirectory path dir = dir `joinFileName` filenameOf path
-
-escapeSpaces :: String -> String
-escapeSpaces = foldr (\c s -> if isSpace c then '\\':c:s else c:s) ""
-
-isPathSeparator :: Char -> Bool
-isPathSeparator ch =
-#ifdef mingw32_TARGET_OS
- ch == '/' || ch == '\\'
-#else
- ch == '/'
-#endif
-
---------------------------------------------------------------
--- * Search path
---------------------------------------------------------------
-
--- | The function splits the given string to substrings
--- using the 'searchPathSeparator'.
-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 (==searchPathSeparator) s
-
--- | A platform-specific character used to separate search path strings in
--- environment variables. The separator is a colon (\":\") on Unix and Macintosh,
--- and a semicolon (\";\") on the Windows operating system.
-searchPathSeparator :: Char
-#if mingw32_HOST_OS || mingw32_TARGET_OS
-searchPathSeparator = ';'
-#else
-searchPathSeparator = ':'
-#endif
-
------------------------------------------------------------------------------
--- Convert filepath into platform / MSDOS form.
-
--- We maintain path names in Unix form ('/'-separated) right until
--- the last moment. On Windows we dos-ify them just before passing them
--- to the Windows command.
---
--- The alternative, of using '/' consistently on Unix and '\' on Windows,
--- proved quite awkward. There were a lot more calls to platformPath,
--- and even on Windows we might invoke a unix-like utility (eg 'sh'), which
--- interpreted a command line 'foo\baz' as 'foobaz'.
-
-normalisePath :: String -> String
--- Just changes '\' to '/'
-
-pgmPath :: String -- Directory string in Unix format
- -> String -- Program name with no directory separators
- -- (e.g. copy /y)
- -> String -- Program invocation string in native format
-
-#if defined(mingw32_HOST_OS)
---------------------- Windows version ------------------
-normalisePath xs = subst '\\' '/' xs
-pgmPath dir pgm = platformPath dir ++ '\\' : pgm
-platformPath p = subst '/' '\\' p
-
-subst a b ls = map (\ x -> if x == a then b else x) ls
-#else
---------------------- Non-Windows version --------------
-normalisePath xs = xs
-pgmPath dir pgm = dir ++ '/' : pgm
-platformPath stuff = stuff
---------------------------------------------------------
-#endif
-\end{code}
projects / ghc-hetmet.git / blobdiff