X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2Futils%2FUtil.lhs;h=11d1b5e545700e1552773d0870de7ecd96aa603c;hb=153b9cb9b11e05c4edb1b6bc0a7b972660e41f70;hp=1f7289d2aec90ebd12047763d4e4ccbf9a51ff5b;hpb=ee096783fedf17a078700a106adeefba3e5e9ba6;p=ghc-hetmet.git diff --git a/ghc/compiler/utils/Util.lhs b/ghc/compiler/utils/Util.lhs index 1f7289d..11d1b5e 100644 --- a/ghc/compiler/utils/Util.lhs +++ b/ghc/compiler/utils/Util.lhs @@ -1,68 +1,77 @@ % -% (c) The GRASP/AQUA Project, Glasgow University, 1992-1998 +% (c) The University of Glasgow 1992-2002 % \section[Util]{Highly random utility functions} \begin{code} --- IF_NOT_GHC is meant to make this module useful outside the context of GHC -#define IF_NOT_GHC(a) - module Util ( -#if NOT_USED - -- The Eager monad - Eager, thenEager, returnEager, mapEager, appEager, runEager, -#endif -- general list processing zipEqual, zipWithEqual, zipWith3Equal, zipWith4Equal, - zipLazy, stretchZipEqual, + zipLazy, stretchZipWith, mapAndUnzip, mapAndUnzip3, - nOfThem, lengthExceeds, isSingleton, only, - snocView, - isIn, isn'tIn, + nOfThem, filterOut, + lengthExceeds, lengthIs, lengthAtLeast, listLengthCmp, atLength, + isSingleton, only, + notNull, snocView, - -- association lists - assoc, assocUsing, assocDefault, assocDefaultUsing, + isIn, isn'tIn, - -- duplicate handling - hasNoDups, equivClasses, runs, removeDups, equivClassesByUniq, + -- for-loop + nTimes, -- sorting - IF_NOT_GHC(quicksort COMMA stableSortLt COMMA mergesort COMMA) - sortLt, - IF_NOT_GHC(mergeSort COMMA) naturalMergeSortLe, -- from Carsten - IF_NOT_GHC(naturalMergeSort COMMA mergeSortLe COMMA) + sortLe, sortWith, -- transitive closures transitiveClosure, -- accumulating - mapAccumL, mapAccumR, mapAccumB, foldl2, count, + mapAccumL, mapAccumR, mapAccumB, + foldl2, count, + + takeList, dropList, splitAtList, -- comparisons - thenCmp, cmpList, + isEqual, eqListBy, equalLength, compareLength, + thenCmp, cmpList, prefixMatch, suffixMatch, maybePrefixMatch, -- strictness - seqList, ($!), + foldl', seqList, -- pairs - IF_NOT_GHC(cfst COMMA applyToPair COMMA applyToFst COMMA) - IF_NOT_GHC(applyToSnd COMMA foldPair COMMA) - unzipWith + unzipWith, - -- I/O -#if __GLASGOW_HASKELL__ < 402 - , bracket -#endif + global, + -- module names + looksLikeModuleName, + + toArgs, + + -- Floating point stuff + readRational, ) where #include "HsVersions.h" +import Panic ( panic, trace ) +import FastTypes + +#if __GLASGOW_HASKELL__ <= 408 +import EXCEPTION ( catchIO, justIoErrors, raiseInThread ) +#endif +import DATA_IOREF ( IORef, newIORef ) +import UNSAFE_IO ( unsafePerformIO ) + +import qualified List ( elem, notElem ) + +#ifndef DEBUG import List ( zipWith4 ) -import Panic ( panic ) -import Unique ( Unique ) -import UniqFM ( eltsUFM, emptyUFM, addToUFM_C ) +#endif + +import Char ( isUpper, isAlphaNum, isSpace, ord, isDigit ) +import Ratio ( (%) ) infixr 9 `thenCmp` \end{code} @@ -104,10 +113,32 @@ mapEager f (x:xs) = f x `thenEager` \ y -> %************************************************************************ %* * +\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? @@ -154,13 +185,16 @@ zipLazy (x:xs) ~(y:ys) = (x,y) : zipLazy xs ys \begin{code} -stretchZipEqual :: (a -> b -> Maybe a) -> [a] -> [b] -> [a] --- (stretchZipEqual f xs ys) stretches ys to "fit" the places where f returns a Just +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* -stretchZipEqual f [] [] = [] -stretchZipEqual f (x:xs) (y:ys) = case f x y of - Just x' -> x' : stretchZipEqual f xs ys - Nothing -> x : stretchZipEqual f xs (y:ys) +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} @@ -190,15 +224,66 @@ mapAndUnzip3 f (x:xs) 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) is True if length xs > n -(x:xs) `lengthExceeds` n = n < 1 || xs `lengthExceeds` (n - 1) -[] `lengthExceeds` n = n < 0 +-- (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 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 @@ -207,14 +292,6 @@ only (a:_) = a #endif \end{code} -\begin{code} -snocView :: [a] -> ([a], a) -- Split off the last element -snocView xs = go xs [] - where - go [x] acc = (reverse acc, x) - go (x:xs) acc = go xs (x:acc) -\end{code} - Debugging/specialising versions of \tr{elem} and \tr{notElem} \begin{code} @@ -231,256 +308,25 @@ elem__ x (y:ys) = x==y || elem__ x ys notElem__ x [] = True notElem__ x (y:ys) = x /= y && notElem__ x ys -# else {- DEBUG -} +# else /* DEBUG */ isIn msg x ys - = elem ILIT(0) x ys + = elem (_ILIT 0) x ys where elem i _ [] = False elem i x (y:ys) - | i _GE_ ILIT(100) = panic ("Over-long elem in: " ++ msg) - | otherwise = x == y || elem (i _ADD_ ILIT(1)) x 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 + = notElem (_ILIT 0) x ys where notElem i x [] = True notElem i x (y:ys) - | i _GE_ ILIT(100) = panic ("Over-long notElem in: " ++ msg) - | otherwise = x /= y && notElem (i _ADD_ ILIT(1)) x ys - -# endif {- DEBUG -} - -\end{code} - -%************************************************************************ -%* * -\subsection[Utils-assoc]{Association lists} -%* * -%************************************************************************ - -See also @assocMaybe@ and @mkLookupFun@ in module @Maybes@. - -\begin{code} -assoc :: (Eq a) => String -> [(a, b)] -> a -> b -assocDefault :: (Eq a) => b -> [(a, b)] -> a -> b -assocUsing :: (a -> a -> Bool) -> String -> [(a, b)] -> a -> b -assocDefaultUsing :: (a -> a -> Bool) -> b -> [(a, b)] -> a -> b - -assocDefaultUsing eq deflt ((k,v) : rest) key - | k `eq` key = v - | otherwise = assocDefaultUsing eq deflt rest key - -assocDefaultUsing eq deflt [] key = deflt - -assoc crash_msg list key = assocDefaultUsing (==) (panic ("Failed in assoc: " ++ crash_msg)) list key -assocDefault deflt list key = assocDefaultUsing (==) deflt list key -assocUsing eq crash_msg list key = assocDefaultUsing eq (panic ("Failed in assoc: " ++ crash_msg)) list key -\end{code} - -%************************************************************************ -%* * -\subsection[Utils-dups]{Duplicate-handling} -%* * -%************************************************************************ - -\begin{code} -hasNoDups :: (Eq a) => [a] -> Bool - -hasNoDups xs = f [] xs - where - f seen_so_far [] = True - f seen_so_far (x:xs) = if x `is_elem` seen_so_far then - False - else - f (x:seen_so_far) xs - - is_elem = isIn "hasNoDups" -\end{code} - -\begin{code} -equivClasses :: (a -> a -> Ordering) -- Comparison - -> [a] - -> [[a]] - -equivClasses cmp stuff@[] = [] -equivClasses cmp stuff@[item] = [stuff] -equivClasses cmp items - = runs eq (sortLt lt items) - where - eq a b = case cmp a b of { EQ -> True; _ -> False } - lt a b = case cmp a b of { LT -> True; _ -> False } -\end{code} - -The first cases in @equivClasses@ above are just to cut to the point -more quickly... - -@runs@ groups a list into a list of lists, each sublist being a run of -identical elements of the input list. It is passed a predicate @p@ which -tells when two elements are equal. - -\begin{code} -runs :: (a -> a -> Bool) -- Equality - -> [a] - -> [[a]] - -runs p [] = [] -runs p (x:xs) = case (span (p x) xs) of - (first, rest) -> (x:first) : (runs p rest) -\end{code} - -\begin{code} -removeDups :: (a -> a -> Ordering) -- Comparison function - -> [a] - -> ([a], -- List with no duplicates - [[a]]) -- List of duplicate groups. One representative from - -- each group appears in the first result - -removeDups cmp [] = ([], []) -removeDups cmp [x] = ([x],[]) -removeDups cmp xs - = case (mapAccumR collect_dups [] (equivClasses cmp xs)) of { (dups, xs') -> - (xs', dups) } - where - collect_dups dups_so_far [x] = (dups_so_far, x) - collect_dups dups_so_far dups@(x:xs) = (dups:dups_so_far, x) -\end{code} - - -\begin{code} -equivClassesByUniq :: (a -> Unique) -> [a] -> [[a]] - -- NB: it's *very* important that if we have the input list [a,b,c], - -- where a,b,c all have the same unique, then we get back the list - -- [a,b,c] - -- not - -- [c,b,a] - -- Hence the use of foldr, plus the reversed-args tack_on below -equivClassesByUniq get_uniq xs - = eltsUFM (foldr add emptyUFM xs) - where - add a ufm = addToUFM_C tack_on ufm (get_uniq a) [a] - tack_on old new = new++old -\end{code} - -%************************************************************************ -%* * -\subsection[Utils-sorting]{Sorting} -%* * -%************************************************************************ - -%************************************************************************ -%* * -\subsubsection[Utils-quicksorting]{Quicksorts} -%* * -%************************************************************************ - -\begin{code} -#if NOT_USED - --- tail-recursive, etc., "quicker sort" [as per Meira thesis] -quicksort :: (a -> a -> Bool) -- Less-than predicate - -> [a] -- Input list - -> [a] -- Result list in increasing order - -quicksort lt [] = [] -quicksort lt [x] = [x] -quicksort lt (x:xs) = split x [] [] xs - where - split x lo hi [] = quicksort lt lo ++ (x : quicksort lt hi) - split x lo hi (y:ys) | y `lt` x = split x (y:lo) hi ys - | True = split x lo (y:hi) ys -#endif -\end{code} - -Quicksort variant from Lennart's Haskell-library contribution. This -is a {\em stable} sort. - -\begin{code} -stableSortLt = sortLt -- synonym; when we want to highlight stable-ness - -sortLt :: (a -> a -> Bool) -- Less-than predicate - -> [a] -- Input list - -> [a] -- Result list - -sortLt lt l = qsort lt l [] - --- qsort is stable and does not concatenate. -qsort :: (a -> a -> Bool) -- Less-than predicate - -> [a] -- xs, Input list - -> [a] -- r, Concatenate this list to the sorted input list - -> [a] -- Result = sort xs ++ r - -qsort lt [] r = r -qsort lt [x] r = x:r -qsort lt (x:xs) r = qpart lt x xs [] [] r - --- qpart partitions and sorts the sublists --- rlt contains things less than x, --- rge contains the ones greater than or equal to x. --- Both have equal elements reversed with respect to the original list. - -qpart lt x [] rlt rge r = - -- rlt and rge are in reverse order and must be sorted with an - -- anti-stable sorting - rqsort lt rlt (x : rqsort lt rge r) - -qpart lt x (y:ys) rlt rge r = - if lt y x then - -- y < x - qpart lt x ys (y:rlt) rge r - else - -- y >= x - qpart lt x ys rlt (y:rge) r - --- rqsort is as qsort but anti-stable, i.e. reverses equal elements -rqsort lt [] r = r -rqsort lt [x] r = x:r -rqsort lt (x:xs) r = rqpart lt x xs [] [] r - -rqpart lt x [] rle rgt r = - qsort lt rle (x : qsort lt rgt r) - -rqpart lt x (y:ys) rle rgt r = - if lt x y then - -- y > x - rqpart lt x ys rle (y:rgt) r - else - -- y <= x - rqpart lt x ys (y:rle) rgt r -\end{code} - -%************************************************************************ -%* * -\subsubsection[Utils-dull-mergesort]{A rather dull mergesort} -%* * -%************************************************************************ - -\begin{code} -#if NOT_USED -mergesort :: (a -> a -> Ordering) -> [a] -> [a] - -mergesort cmp xs = merge_lists (split_into_runs [] xs) - where - a `le` b = case cmp a b of { LT -> True; EQ -> True; GT -> False } - a `ge` b = case cmp a b of { LT -> False; EQ -> True; GT -> True } - - split_into_runs [] [] = [] - split_into_runs run [] = [run] - split_into_runs [] (x:xs) = split_into_runs [x] xs - split_into_runs [r] (x:xs) | x `ge` r = split_into_runs [r,x] xs - split_into_runs rl@(r:rs) (x:xs) | x `le` r = split_into_runs (x:rl) xs - | True = rl : (split_into_runs [x] xs) - - merge_lists [] = [] - merge_lists (x:xs) = merge x (merge_lists xs) - - merge [] ys = ys - merge xs [] = xs - merge xl@(x:xs) yl@(y:ys) - = case cmp x y of - EQ -> x : y : (merge xs ys) - LT -> x : (merge xs yl) - GT -> y : (merge xl ys) -#endif + | 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} %************************************************************************ @@ -526,34 +372,24 @@ Carsten \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 +-- Here is a `better' definition of group. -{- -Date: Mon, 12 Feb 1996 15:09:41 +0000 -From: Andy Gill - -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 - | not (x `p` x_max) = group' xs x_min x (s . (x :)) - | x `p` x_min = group' xs x x_max ((x :) . 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 :) - --- This one works forwards *and* backwards, as well as also being --- faster that the one in Util.lhs. - -{- ORIG: -group p [] = [[]] -group p (x:xs) = - let ((h1:t1):tt1) = group p xs - (t,tt) = if null xs then ([],[]) else - if x `p` h1 then (h1:t1,tt1) else - ([], (h1:t1):tt1) - in ((x:t):tt) --} + -- 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 @@ -572,19 +408,28 @@ balancedFold' :: (a -> a -> a) -> [a] -> [a] balancedFold' f (x:y:xs) = f x y : balancedFold' f xs balancedFold' f xs = xs -generalMergeSort p [] = [] -generalMergeSort p xs = (balancedFold (generalMerge p) . map (: [])) 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 -naturalMergeSortLe le = generalNaturalMergeSort 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} %************************************************************************ @@ -675,6 +520,16 @@ mapAccumB f a b (x:xs) = (a'',b'',y:ys) (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} @@ -692,6 +547,32 @@ 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 + +\end{code} + %************************************************************************ %* * @@ -700,11 +581,33 @@ count p (x:xs) | p x = 1 + count p xs %************************************************************************ \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 @@ -716,16 +619,22 @@ cmpList cmp (a:as) (b:bs) \end{code} \begin{code} -cmpString :: String -> String -> Ordering - -cmpString [] [] = EQ -cmpString (x:xs) (y:ys) = if x == y then cmpString xs ys - else if x < y then LT - else GT -cmpString [] ys = LT -cmpString xs [] = GT -\end{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) +\end{code} %************************************************************************ %* * @@ -736,14 +645,17 @@ cmpString xs [] = GT 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) @@ -752,11 +664,7 @@ applyToFst f (x,y) = (f x,y) applyToSnd :: (b -> d) -> (a,b) -> (a,d) applyToSnd f (x,y) = (x,f y) - -foldPair :: (a->a->a,b->b->b) -> (a,b) -> [(a,b)] -> (a,b) -foldPair fg ab [] = ab -foldPair fg@(f,g) ab ((a,b):abs) = (f a u,g b v) - where (u,v) = foldPair fg ab abs +#endif \end{code} \begin{code} @@ -765,27 +673,99 @@ unzipWith f pairs = map ( \ (a, b) -> f a b ) pairs \end{code} \begin{code} -#if __HASKELL1__ > 4 seqList :: [a] -> b -> b -#else -seqList :: (Eval a) => [a] -> b -> b -#endif seqList [] b = b seqList (x:xs) b = x `seq` seqList xs b +\end{code} -#if __HASKELL1__ <= 4 -($!) :: (Eval a) => (a -> b) -> a -> b -f $! x = x `seq` f x -#endif +Global variables: + +\begin{code} +global :: a -> IORef a +global a = unsafePerformIO (newIORef a) \end{code} +Module names: + \begin{code} -#if __GLASGOW_HASKELL__ < 402 -bracket :: IO a -> (a -> IO b) -> (a -> IO c) -> IO c -bracket before after thing = do - a <- before - r <- (thing a) `catch` (\err -> after a >> fail err) - after a - return r -#endif +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) \end{code}