% (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 (
- debugIsOn, ghciTablesNextToCode, picIsOn,
+ -- * Flags dependent on the compiler build
+ ghciSupported, debugIsOn, ghciTablesNextToCode, picIsOn,
isWindowsHost, isWindowsTarget, isDarwinTarget,
- -- general list processing
+ -- * General list processing
zipEqual, zipWithEqual, zipWith3Equal, zipWith4Equal,
zipLazy, stretchZipWith,
+
+ unzipWith,
+
mapFst, mapSnd,
mapAndUnzip, mapAndUnzip3,
nOfThem, filterOut, partitionWith, splitEithers,
- foldl1',
+
+ foldl1', foldl2, count, all2,
lengthExceeds, lengthIs, lengthAtLeast,
listLengthCmp, atLength, equalLength, compareLength,
isIn, isn'tIn,
- -- for-loop
+ -- * List operations controlled by another list
+ takeList, dropList, splitAtList, split,
+ dropTail,
+
+ -- * For loop
nTimes,
- -- sorting
+ -- * Sorting
sortLe, sortWith, on,
- -- transitive closures
- transitiveClosure,
-
- -- accumulating
- foldl2, count, all2,
-
- takeList, dropList, splitAtList, split,
-
- -- comparisons
+ -- * Comparisons
isEqual, eqListBy,
- thenCmp, cmpList, maybePrefixMatch,
+ thenCmp, cmpList,
removeSpaces,
- -- strictness
- seqList,
-
- -- pairs
- unzipWith,
+ -- * Transitive closures
+ transitiveClosure,
- global, consIORef,
+ -- * Strictness
+ seqList,
- -- module names
+ -- * Module names
looksLikeModuleName,
+ -- * Argument processing
getCmd, toCmdArgs, toArgs,
- -- Floating point stuff
+ -- * Floating point
readRational,
- -- IO-ish utilities
+ -- * IO-ish utilities
createDirectoryHierarchy,
doesDirNameExist,
modificationTimeIfExists,
- later, handleDyn, handle,
+ global, consIORef, globalMVar, globalEmptyMVar,
- -- Filename utils
+ -- * Filenames and paths
Suffix,
splitLongestPrefix,
escapeSpaces,
import Panic
-import Control.Exception ( Exception(..), finally, catchDyn, throw )
-import qualified Control.Exception as Exception
-import Data.Dynamic ( Typeable )
import Data.IORef ( IORef, newIORef )
import System.IO.Unsafe ( unsafePerformIO )
import Data.IORef ( readIORef, writeIORef )
import Data.List hiding (group)
+import Control.Concurrent.MVar ( MVar, newMVar, newEmptyMVar )
-import qualified Data.List as List ( elem )
#ifdef DEBUG
-import qualified Data.List as List ( notElem )
+import qualified Data.List as List ( elem, notElem )
import FastTypes
#endif
import System.IO.Error as IO ( catch, isDoesNotExistError )
import System.Directory ( doesDirectoryExist, createDirectory,
getModificationTime )
-import System.FilePath hiding ( searchPathSeparator )
+import System.FilePath
import Data.Char ( isUpper, isAlphaNum, isSpace, ord, isDigit )
import Data.Ratio ( (%) )
import System.Time ( ClockTime )
%************************************************************************
%* *
-\subsection{Is DEBUG on, are we on Windows?}
+\subsection{Is DEBUG on, are we on Windows, etc?}
%* *
%************************************************************************
+These booleans are global constants, set by CPP flags. They allow us to
+recompile a single module (this one) to change whether or not debug output
+appears. They sometimes let us avoid even running CPP elsewhere.
+
+It's important that the flags are literal constants (True/False). Then,
+with -0, tests of the flags in other modules will simplify to the correct
+branch of the conditional, thereby dropping debug code altogether when
+the flags are off.
+
\begin{code}
+ghciSupported :: Bool
+#ifdef GHCI
+ghciSupported = True
+#else
+ghciSupported = False
+#endif
+
debugIsOn :: Bool
#ifdef DEBUG
debugIsOn = True
%************************************************************************
\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
\begin{code}
filterOut :: (a->Bool) -> [a] -> [a]
--- Like filter, only reverses the sense of the test
+-- ^ 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
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)
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)
\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 [] _ = []
-- We want to write this, but with GHC 6.4 we get a warning, so it
\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 _ _ _ [] _ = []
stretchZipWith p z f (x:xs) ys
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]
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
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
snocView [] = Nothing
\end{code}
\begin{code}
--- This (with a more general type) is Data.List.stripPrefix from GHC 6.8.
--- This definition can be removed once we require at least 6.8 to build.
-maybePrefixMatch :: String -> String -> Maybe String
-maybePrefixMatch [] rest = Just rest
-maybePrefixMatch (_:_) [] = Nothing
-maybePrefixMatch (p:pat) (r:rest)
- | p == r = maybePrefixMatch pat rest
- | otherwise = Nothing
-
removeSpaces :: String -> String
removeSpaces = reverse . dropWhile isSpace . reverse . dropWhile isSpace
\end{code}
writeIORef var (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}
"" -> return True -- XXX Hack
_ -> doesDirectoryExist (takeDirectory fpath)
--- -----------------------------------------------------------------------------
--- Exception utils
-
-later :: IO b -> IO a -> IO a
-later = flip finally
-
-handleDyn :: Typeable ex => (ex -> IO a) -> IO a -> IO a
-handleDyn = flip catchDyn
-
-handle :: (Exception -> IO a) -> IO a -> IO a
-handle h f = f `Exception.catch` \e -> case e of
- ExitException _ -> throw e
- _ -> h e
-
-- --------------------------------------------------------------
-- check existence & modification time at the same time
#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
+ (chunk', rest') = break isSearchPathSeparator s
data Direction = Forwards | Backwards
projects / ghc-hetmet.git / blobdiff