%
+% (c) The University of Glasgow 2006
% (c) The University of Glasgow 1992-2002
%
-\section[Util]{Highly random utility functions}
\begin{code}
+-- | Highly random utility functions
module Util (
+ -- * Flags dependent on the compiler build
+ ghciSupported, debugIsOn, ghciTablesNextToCode, isDynamicGhcLib,
+ isWindowsHost, isWindowsTarget, isDarwinTarget,
- -- general list processing
- zipEqual, zipWithEqual, zipWith3Equal, zipWith4Equal,
+ -- * General list processing
+ zipEqual, zipWithEqual, zipWith3Equal, zipWith4Equal,
zipLazy, stretchZipWith,
- mapFst, mapSnd,
- mapAndUnzip, mapAndUnzip3,
- nOfThem, filterOut,
+
+ unzipWith,
+
+ mapFst, mapSnd,
+ mapAndUnzip, mapAndUnzip3,
+ nOfThem, filterOut, partitionWith, splitEithers,
+
+ foldl1', foldl2, count, all2,
- lengthExceeds, lengthIs, lengthAtLeast,
- listLengthCmp, atLength, equalLength, compareLength,
+ lengthExceeds, lengthIs, lengthAtLeast,
+ listLengthCmp, atLength, equalLength, compareLength,
- isSingleton, only, singleton,
- notNull, snocView,
+ isSingleton, only, singleton,
+ notNull, snocView,
- isIn, isn'tIn,
+ isIn, isn'tIn,
- -- for-loop
- nTimes,
+ -- * Tuples
+ fstOf3, sndOf3, thirdOf3,
- -- sorting
- sortLe, sortWith,
+ -- * List operations controlled by another list
+ takeList, dropList, splitAtList, split,
+ dropTail,
- -- transitive closures
- transitiveClosure,
+ -- * For loop
+ nTimes,
- -- accumulating
- mapAccumL, mapAccumR, mapAccumB,
- foldl2, count, all2,
-
- takeList, dropList, splitAtList, split,
+ -- * Sorting
+ sortLe, sortWith, on,
- -- comparisons
- isEqual, eqListBy,
- thenCmp, cmpList, prefixMatch, suffixMatch, maybePrefixMatch,
- removeSpaces,
+ -- * Comparisons
+ isEqual, eqListBy,
+ thenCmp, cmpList,
+ removeSpaces,
+
+ -- * Edit distance
+ fuzzyMatch,
- -- strictness
- foldl', seqList,
+ -- * Transitive closures
+ transitiveClosure,
- -- pairs
- unzipWith,
+ -- * Strictness
+ seqList,
- global, consIORef,
+ -- * Module names
+ looksLikeModuleName,
- -- module names
- looksLikeModuleName,
-
- toArgs,
+ -- * Argument processing
+ getCmd, toCmdArgs, toArgs,
- -- Floating point stuff
- readRational,
+ -- * Floating point
+ readRational,
- -- IO-ish utilities
- createDirectoryHierarchy,
- doesDirNameExist,
- modificationTimeIfExists,
+ -- * IO-ish utilities
+ createDirectoryHierarchy,
+ doesDirNameExist,
+ modificationTimeIfExists,
- later, handleDyn, handle,
+ global, consIORef, globalMVar, globalEmptyMVar,
- -- Filename utils
- Suffix,
- splitFilename, suffixOf, basenameOf, joinFileExt,
- splitFilenameDir, joinFileName,
- splitFilename3,
- splitLongestPrefix,
- replaceFilenameSuffix, directoryOf, filenameOf,
- replaceFilenameDirectory,
- escapeSpaces, isPathSeparator,
- parseSearchPath,
- normalisePath, platformPath, pgmPath,
+ -- * Filenames and paths
+ Suffix,
+ splitLongestPrefix,
+ escapeSpaces,
+ parseSearchPath,
+ Direction(..), reslash,
+
+ -- * Utils for defining Data instances
+ abstractConstr, abstractDataType, mkNoRepType
) 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 Panic
-import qualified List ( elem, notElem )
+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 )
-#ifndef DEBUG
-import List ( zipWith4 )
+#ifdef DEBUG
+import FastTypes
#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 )
+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{The Eager monad}
-%* *
+%* *
+\subsection{Is DEBUG on, are we on Windows, etc?}
+%* *
%************************************************************************
-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.
+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}
-#if NOT_USED
+ghciSupported :: Bool
+#ifdef GHCI
+ghciSupported = True
+#else
+ghciSupported = False
+#endif
-type Eager ans a = (a -> ans) -> ans
+debugIsOn :: Bool
+#ifdef DEBUG
+debugIsOn = True
+#else
+debugIsOn = False
+#endif
-runEager :: Eager a a -> a
-runEager m = m (\x -> x)
+ghciTablesNextToCode :: Bool
+#ifdef GHCI_TABLES_NEXT_TO_CODE
+ghciTablesNextToCode = True
+#else
+ghciTablesNextToCode = False
+#endif
-appEager :: Eager ans a -> (a -> ans) -> ans
-appEager m cont = m cont
+isDynamicGhcLib :: Bool
+#ifdef DYNAMIC
+isDynamicGhcLib = True
+#else
+isDynamicGhcLib = False
+#endif
-thenEager :: Eager ans a -> (a -> Eager ans b) -> Eager ans b
-thenEager m k cont = m (\r -> k r cont)
+isWindowsHost :: Bool
+#ifdef mingw32_HOST_OS
+isWindowsHost = True
+#else
+isWindowsHost = False
+#endif
-returnEager :: a -> Eager ans a
-returnEager v cont = cont v
+isWindowsTarget :: Bool
+#ifdef mingw32_TARGET_OS
+isWindowsTarget = True
+#else
+isWindowsTarget = False
+#endif
-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)
+isDarwinTarget :: Bool
+#ifdef darwin_TARGET_OS
+isDarwinTarget = True
+#else
+isDarwinTarget = False
#endif
\end{code}
%************************************************************************
-%* *
+%* *
\subsection{A for loop}
-%* *
+%* *
%************************************************************************
\begin{code}
--- Compose a function with itself n times. (nth rather than twice)
+-- | 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}
+\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]
--- Like filter, only reverses the sense of the test
-filterOut p [] = []
+-- ^ Like filter, only it reverses the sense of the test
+filterOut _ [] = []
filterOut p (x:xs) | p x = filterOut p xs
- | otherwise = x : filterOut p xs
+ | otherwise = x : filterOut p xs
+
+partitionWith :: (a -> Either b c) -> [a] -> ([b], [c])
+-- ^ Uses a function to determine which of two output lists an input element should join
+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])
+-- ^ Teases a list of 'Either's apart into two lists
+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
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]
+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
zipWith3Equal _ = zipWith3
zipWith4Equal _ = zipWith4
#else
-zipEqual msg [] [] = []
+zipEqual _ [] [] = []
zipEqual msg (a:as) (b:bs) = (a,b) : zipEqual msg as bs
-zipEqual msg as bs = panic ("zipEqual: unequal lists:"++msg)
+zipEqual msg _ _ = 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)
+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 msg _ [] [] [] = []
-zipWith3Equal msg _ _ _ _ = panic ("zipWith3Equal: unequal lists:"++msg)
+ = 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 msg _ [] [] [] [] = []
-zipWith4Equal msg _ _ _ _ _ = panic ("zipWith4Equal: unequal lists:"++msg)
+ = 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 is lazy in the second list (observe the ~)
-
+-- | 'zipLazy' is a kind of 'zip' that 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
+zipLazy [] _ = []
+-- We want to write this, but with GHC 6.4 we get a warning, so it
+-- doesn't validate:
+-- zipLazy (x:xs) ~(y:ys) = (x,y) : zipLazy xs ys
+-- so we write this instead:
+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 p z f xs ys) stretches ys by inserting z in
--- the places where p returns *True*
+-- ^ @stretchZipWith p z f xs ys@ stretches @ys@ by inserting @z@ in
+-- the places where @p@ returns @True@
-stretchZipWith p z f [] ys = []
+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
+ [] -> []
+ (y:ys) -> f x y : stretchZipWith p z f xs ys
\end{code}
mapAndUnzip :: (a -> (b, c)) -> [a] -> ([b], [c])
-mapAndUnzip f [] = ([],[])
+mapAndUnzip _ [] = ([], [])
mapAndUnzip f (x:xs)
- = let
- (r1, r2) = f x
- (rs1, rs2) = mapAndUnzip f 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 _ [] = ([], [], [])
mapAndUnzip3 f (x:xs)
- = let
- (r1, r2, r3) = f x
- (rs1, rs2, rs3) = mapAndUnzip3 f xs
+ = let (r1, r2, r3) = f x
+ (rs1, rs2, rs3) = mapAndUnzip3 f xs
in
(r1:rs1, r2:rs2, r3:rs3)
\end{code}
nOfThem :: Int -> a -> [a]
nOfThem n thing = replicate n thing
--- 'atLength atLen atEnd ls n' unravels list 'ls' to position 'n';
--- specification:
+-- | @atLength atLen atEnd ls n@ unravels list @ls@ to position @n@. Precisely:
--
+-- @
-- 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
+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.
+-- Some special cases of atLength:
+
lengthExceeds :: [a] -> Int -> Bool
--- (lengthExceeds xs n) = (length xs > n)
+-- ^ > (lengthExceeds xs n) = (length xs > n)
lengthExceeds = atLength notNull (const False)
lengthAtLeast :: [a] -> Int -> Bool
lengthIs :: [a] -> Int -> Bool
lengthIs = atLength null (==0)
-listLengthCmp :: [a] -> Int -> Ordering
-listLengthCmp = atLength atLen atEnd
+listLengthCmp :: [a] -> Int -> Ordering
+listLengthCmp = atLength atLen atEnd
where
atEnd 0 = EQ
atEnd x
atLen _ = GT
equalLength :: [a] -> [b] -> Bool
-equalLength [] [] = True
+equalLength [] [] = True
equalLength (_:xs) (_:ys) = equalLength xs ys
-equalLength xs ys = False
+equalLength _ _ = False
compareLength :: [a] -> [b] -> Ordering
-compareLength [] [] = EQ
+compareLength [] [] = EQ
compareLength (_:xs) (_:ys) = compareLength xs ys
-compareLength [] _ys = LT
-compareLength _xs [] = GT
+compareLength [] _ = LT
+compareLength _ [] = GT
----------------------------
singleton :: a -> [a]
singleton x = [x]
isSingleton :: [a] -> Bool
-isSingleton [x] = True
-isSingleton _ = False
+isSingleton [_] = True
+isSingleton _ = False
notNull :: [a] -> Bool
notNull [] = False
#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
+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
+isIn _msg x ys = x `elem` ys
+isn'tIn _msg x ys = x `notElem` ys
# else /* DEBUG */
isIn msg x ys
- = elem (_ILIT 0) x ys
+ = elem100 (_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
+ 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
- = notElem (_ILIT 0) x ys
+ = notElem100 (_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
+ 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}
\begin{code}
group :: (a -> a -> Bool) -> [a] -> [[a]]
--- Given a <= function, group finds maximal contiguous up-runs
+-- 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
--
-- From: Andy Gill <andy@dcs.gla.ac.uk>
-- Here is a `better' definition of group.
-group p [] = []
+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 :)
- -- NB: the 'not' is essential for stablity
- -- x `p` x_min would reverse equal elements
+ 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
+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
-- 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 _ [] = 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' f xs = xs
+balancedFold' _ xs = xs
-generalNaturalMergeSort p [] = []
+generalNaturalMergeSort :: (a -> a -> Bool) -> [a] -> [a]
+generalNaturalMergeSort _ [] = []
generalNaturalMergeSort p xs = (balancedFold (generalMerge p) . group p) xs
#if NOT_USED
sortWith :: Ord b => (a->b) -> [a] -> [a]
sortWith get_key xs = sortLe le xs
where
- x `le` y = get_key x < get_key y
+ 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]) -- Successor function
- -> (a -> a -> Bool) -- Equality predicate
- -> [a]
- -> [a] -- The transitive closure
+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 [] = done
go done (x:xs) | x `is_in` done = go done xs
- | otherwise = go (x:done) (succ x ++ xs)
+ | otherwise = go (x:done) (succ x ++ xs)
- x `is_in` [] = False
+ _ `is_in` [] = False
x `is_in` (y:ys) | eq x y = True
- | otherwise = x `is_in` ys
+ | 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 _ 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
--- True if the lists are the same length, and
+-- True if the lists are the same length, and
-- all corresponding elements satisfy the predicate
-all2 p [] [] = True
+all2 _ [] [] = True
all2 p (x:xs) (y:ys) = p x y && all2 p xs ys
-all2 p xs ys = False
+all2 _ _ _ = False
\end{code}
Count the number of times a predicate is true
\begin{code}
count :: (a -> Bool) -> [a] -> Int
-count p [] = 0
+count _ [] = 0
count p (x:xs) | p x = 1 + count p xs
- | otherwise = count p xs
+ | otherwise = count p xs
\end{code}
@splitAt@, @take@, and @drop@ but with length of another
\begin{code}
takeList :: [b] -> [a] -> [a]
takeList [] _ = []
-takeList (_:xs) ls =
+takeList (_:xs) ls =
case ls of
[] -> []
(y:ys) -> y : takeList xs ys
where
(ys', ys'') = splitAtList xs ys
+-- drop from the end of a list
+dropTail :: Int -> [a] -> [a]
+dropTail n = reverse . drop n . reverse
+
snocView :: [a] -> Maybe ([a],a)
- -- Split off the last element
+ -- 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
+ where
+ -- Invariant: second arg is non-empty
+ 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
+ [] -> [chunk]
+ _:rest -> chunk : split c rest
where (chunk, rest) = break (==c) s
\end{code}
%************************************************************************
-%* *
+%* *
\subsection[Utils-comparison]{Comparisons}
-%* *
+%* *
%************************************************************************
\begin{code}
thenCmp :: Ordering -> Ordering -> Ordering
{-# INLINE thenCmp #-}
-thenCmp EQ any = any
-thenCmp other any = other
+thenCmp EQ ordering = ordering
+thenCmp ordering _ = ordering
eqListBy :: (a->a->Bool) -> [a] -> [a] -> Bool
-eqListBy eq [] [] = True
+eqListBy _ [] [] = True
eqListBy eq (x:xs) (y:ys) = eq x y && eqListBy eq xs ys
-eqListBy eq xs ys = False
+eqListBy _ _ _ = False
cmpList :: (a -> a -> Ordering) -> [a] -> [a] -> Ordering
-- `cmpList' uses a user-specified comparer
-cmpList cmp [] [] = EQ
-cmpList cmp [] _ = LT
-cmpList cmp _ [] = GT
+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}
-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}
-%* *
+%* *
+\subsection{Edit distance}
+%* *
%************************************************************************
-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}
+-- | Find the "restricted" Damerau-Levenshtein edit distance between two strings. See: <http://en.wikipedia.org/wiki/Damerau-Levenshtein_distance>.
+-- Based on the algorithm presented in "A Bit-Vector Algorithm for Computing Levenshtein and Damerau Edit Distances" in PSC'02 (Heikki Hyyro).
+-- See http://www.cs.uta.fi/~helmu/pubs/psc02.pdf and http://www.cs.uta.fi/~helmu/pubs/PSCerr.html for an explanation
+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 -- n must be larger so this check is sufficient
+ then restrictedDamerauLevenshteinDistance' (undefined :: Word32) m n str1 str2
+ else restrictedDamerauLevenshteinDistance' (undefined :: Integer) m n str1 str2
+ | otherwise = if m <= 32 -- m must be larger so this check is sufficient
+ 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) -- No need to mask the shiftL because of the restricted range of 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')
-The following provide us higher order functions that, when applied
-to a function, operate on pairs.
+#ifdef __GLASGOW_HASKELL__
+{-# SPECIALIZE INLINE restrictedDamerauLevenshteinDistance' :: Word32 -> Int -> Int -> String -> String -> Int #-}
+{-# SPECIALIZE INLINE restrictedDamerauLevenshteinDistance' :: Integer -> Int -> Int -> String -> String -> Int #-}
-\begin{code}
-#if NOT_USED
-applyToPair :: ((a -> c),(b -> d)) -> (a,b) -> (c,d)
-applyToPair (f,g) (x,y) = (f x, g y)
+{-# SPECIALIZE restrictedDamerauLevenshteinDistanceWorker :: IM.IntMap Word32 -> Word32 -> Word32 -> (Word32, Word32, Word32, Word32, Int) -> Char -> (Word32, Word32, Word32, Word32, Int) #-}
+{-# SPECIALIZE restrictedDamerauLevenshteinDistanceWorker :: IM.IntMap Integer -> Integer -> Integer -> (Integer, Integer, Integer, Integer, Int) -> Char -> (Integer, Integer, Integer, Integer, Int) #-}
-applyToFst :: (a -> c) -> (a,b)-> (c,b)
-applyToFst f (x,y) = (f x,y)
+{-# SPECIALIZE INLINE sizedComplement :: Word32 -> Word32 -> Word32 #-}
+{-# SPECIALIZE INLINE sizedComplement :: Integer -> Integer -> Integer #-}
-applyToSnd :: (b -> d) -> (a,b) -> (a,d)
-applyToSnd f (x,y) = (x,f y)
+{-# SPECIALIZE matchVectors :: String -> IM.IntMap Word32 #-}
+{-# SPECIALIZE matchVectors :: String -> IM.IntMap Integer #-}
#endif
+
+-- | Search for possible matches to the users input in the given list, returning a small number of ranked results
+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 -- Work out an approriate match threshold (about a quarter of the # of characters the user entered)
+ 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
\begin{code}
consIORef :: IORef [a] -> a -> IO ()
consIORef var x = do
- xs <- readIORef var
- writeIORef var (x:xs)
+ 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 == '_') && go cs
+ 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.
+Akin to @Prelude.words@, but acts like the Bourne shell, treating
+quoted strings as Haskell Strings, and also parses Haskell [String]
+syntax.
\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]
+getCmd :: String -> Either String -- Error
+ (String, String) -- (Cmd, Rest)
+getCmd s = case break isSpace $ dropWhile isSpace s of
+ ([], _) -> Left ("Couldn't find command in " ++ show s)
+ res -> Right res
+
+toCmdArgs :: String -> Either String -- Error
+ (String, [String]) -- (Cmd, Args)
+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 -- Error
+ [String] -- Args
+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
- -- strip away dquotes; assume first and last chars contain quotes.
- stripQuotes :: String -> String
- stripQuotes ('"':xs) = init xs
- stripQuotes xs = xs
+ toArgs' s = case dropWhile isSpace s of
+ [] -> Right []
+ ('"' : _) -> case reads s of
+ [(arg, rest)]
+ -- rest must either be [] or start with a space
+ | 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}
-- -----------------------------------------------------------------------------
\begin{code}
readRational__ :: ReadS Rational -- NB: doesn't handle leading "-"
-readRational__ r = do
+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)
+ (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 = return (0,s)
readExp' ('+':s) = readDec s
- readExp' ('-':s) = do
- (k,t) <- readDec s
- return (-k,t)
- 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
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)
+ [x] -> x
+ [] -> error ("readRational: no parse:" ++ top_s)
+ _ -> error ("readRational: ambiguous parse:" ++ top_s)
-----------------------------------------------------------------------------
-- Create a hierarchy of directories
createDirectoryHierarchy :: FilePath -> IO ()
+createDirectoryHierarchy dir | isDrive dir = return () -- XXX Hack
createDirectoryHierarchy dir = do
b <- doesDirectoryExist dir
- when (not b) $ do
- createDirectoryHierarchy (directoryOf dir)
- createDirectory dir
+ unless b $ do createDirectoryHierarchy (takeDirectory 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
+doesDirNameExist fpath = case takeDirectory fpath of
+ "" -> return True -- XXX Hack
+ _ -> doesDirectoryExist (takeDirectory fpath)
-- --------------------------------------------------------------
-- 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
+ `IO.catch` \e -> if isDoesNotExistError e
+ then return Nothing
+ else ioError e
-- split a string at the last character where 'pred' is True,
-- returning a pair of strings. The first component holds the 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
+ -- 'tail' drops the char satisfying 'pred'
+ 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) ""
-isPathSeparator :: Char -> Bool
-isPathSeparator ch =
-#ifdef mingw32_TARGET_OS
- ch == '/' || ch == '\\'
-#else
- ch == '/'
-#endif
+type Suffix = String
--------------------------------------------------------------
-- * Search path
split :: String -> [String]
split s =
case rest' of
- [] -> [chunk]
+ [] -> [chunk]
_:rest -> chunk : split rest
where
- chunk =
+ chunk =
case chunk' of
#ifdef mingw32_HOST_OS
('\"':xs@(_:_)) | last xs == '\"' -> init xs
#endif
_ -> chunk'
- (chunk', rest') = break (==searchPathSeparator) s
+ (chunk', rest') = break isSearchPathSeparator 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
+data Direction = Forwards | Backwards
------------------------------------------------------------------------------
--- 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
---------------------------------------------------------
+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}
+-- Old GHC versions come with a base library with this function misspelled.
+#if __GLASGOW_HASKELL__ < 612
+mkNoRepType :: String -> DataType
+mkNoRepType = mkNorepType
#endif
\end{code}
+
projects / ghc-hetmet.git / blobdiff