Cabal-2.0.1.0: A framework for packaging Haskell software

Copyright | Isaac Jones Simon Marlow 2003-2004
License | BSD3 portions Copyright (c) 2007, Galois Inc.
Maintainer | cabal-devel@haskell.org
Portability | portable
Safe Haskell | None
Language | Haskell2010

Distribution.Simple.Utils

Contents

- logging and errors
- exceptions
- running programs
- copying files
- installing files
- File permissions
- file names
- finding files
- environment variables
- simple file globbing
- modification time
- temp files and dirs
- .cabal and .buildinfo files
- reading and writing files safely
- Unicode
- BOM
- generic utils
- FilePath stuff

Description

A large and somewhat miscellaneous collection of utility functions used throughout the rest of the Cabal lib and in other tools that use the Cabal lib like `cabal-install`. It has a very simple set of logging actions. It has low level functions for running programs, a bunch of wrappers for various directory and file functions that do extra logging.

Synopsis

- cabalVersion :: Version
- die :: String -> IO a
- dieWithLocation :: FilePath -> Maybe Int -> String -> IO a
- dieNoVerbosity :: String -> IO a
- die' :: Verbosity -> String -> IO a
- dieWithLocation' :: Verbosity -> FilePath -> Maybe Int -> String -> IO a
- dieNoWrap :: Verbosity -> String -> IO a
- topHandler :: IO a -> IO a
- topHandlerWith :: forall a. (SomeException -> IO a) -> IO a -> IO a
- warn :: Verbosity -> String -> IO ()
- notice :: Verbosity -> String -> IO ()
- noticeNoWrap :: Verbosity -> String -> IO ()
- noticeDoc :: Verbosity -> Doc -> IO ()
- setupMessage :: Verbosity -> String -> PackageIdentifier -> IO ()
- info :: Verbosity -> String -> IO ()
- infoNoWrap :: Verbosity -> String -> IO ()
- debug :: Verbosity -> String -> IO ()
- debugNoWrap :: Verbosity -> String -> IO ()
- chattyTry :: String -> IO () -> IO ()
- annotateIO :: Verbosity -> IO a -> IO a
- printRawCommandAndArgs :: Verbosity -> FilePath -> [String] -> IO ()
- printRawCommandAndArgsAndEnv :: Verbosity -> FilePath -> [String] -> Maybe FilePath -> Maybe [(String, String)] -> IO ()
- handleDoesNotExist :: a -> NoCallStackIO a -> NoCallStackIO a
- rawSystemExit :: Verbosity -> FilePath -> [String] -> IO ()
- rawSystemExitCode :: Verbosity -> FilePath -> [String] -> IO ExitCode
- rawSystemExitWithEnv :: Verbosity -> FilePath -> [String] -> [(String, String)] -> IO ()
- rawSystemStdout :: Verbosity -> FilePath -> [String] -> IO String
- rawSystemStdInOut :: Verbosity -> FilePath -> [String] -> Maybe FilePath -> Maybe [(String, String)] -> Maybe (String, Bool) -> Bool -> IO (String, String, ExitCode)
- rawSystemIOWithEnv :: Verbosity -> FilePath -> [String] -> Maybe FilePath -> Maybe [(String, String)] -> Maybe Handle -> Maybe Handle -> Maybe Handle -> IO ExitCode
- createProcessWithEnv :: Verbosity -> FilePath -> [String] -> Maybe FilePath -> Maybe [(String, String)] -> StdStream -> StdStream -> StdStream -> IO (Maybe Handle, Maybe Handle, Maybe Handle, ProcessHandle)
- maybeExit :: IO ExitCode -> IO ()
- xargs :: Int -> ([String] -> IO ()) -> [String] -> [String] -> IO ()
- findProgramLocation :: Verbosity -> FilePath -> IO (Maybe FilePath)
- findProgramVersion :: String -> (String -> String) -> Verbosity -> FilePath -> IO (Maybe Version)
- smartCopySources :: Verbosity -> [FilePath] -> FilePath -> [ModuleName] -> [String] -> IO ()
- createDirectoryIfMissingVerbose :: Verbosity -> Bool -> FilePath -> IO ()
- copyFileVerbose :: Verbosity -> FilePath -> FilePath -> IO ()
- copyDirectoryRecursiveVerbose :: Verbosity -> FilePath -> FilePath -> IO ()
- copyFiles :: Verbosity -> FilePath -> [(FilePath, FilePath)] -> IO ()
- copyFileTo :: Verbosity -> FilePath -> FilePath -> IO ()
- installOrdinaryFile :: Verbosity -> FilePath -> FilePath -> IO ()
- installExecutableFile :: Verbosity -> FilePath -> FilePath -> IO ()
- installMaybeExecutableFile :: Verbosity -> FilePath -> FilePath -> IO ()
- installOrdinaryFiles :: Verbosity -> FilePath -> [(FilePath, FilePath)] -> IO ()
- installExecutableFiles :: Verbosity -> FilePath -> [(FilePath, FilePath)] -> IO ()
- installMaybeExecutableFiles :: Verbosity -> FilePath -> [(FilePath, FilePath)] -> IO ()
- installDirectoryContents :: Verbosity -> FilePath -> FilePath -> IO ()
- copyDirectoryRecursive :: Verbosity -> FilePath -> FilePath -> IO ()
- doesExecutableExist :: FilePath -> NoCallStackIO Bool
- setFileOrdinary :: FilePath -> NoCallStackIO ()
- setFileExecutable :: FilePath -> NoCallStackIO ()
- currentDir :: FilePath
- shortRelativePath :: FilePath -> FilePath -> FilePath
- dropExeExtension :: FilePath -> FilePath
- exeExtensions :: [String]
- findFile :: [FilePath] -> FilePath -> IO FilePath
- findFirstFile :: (a -> FilePath) -> [a] -> NoCallStackIO (Maybe a)
- findFileWithExtension :: [String] -> [FilePath] -> FilePath -> NoCallStackIO (Maybe FilePath)
- findFileWithExtension' :: [String] -> [FilePath] -> FilePath -> NoCallStackIO (Maybe (FilePath, FilePath))
- findAllFilesWithExtension :: [String] -> [FilePath] -> FilePath -> NoCallStackIO [FilePath]
- findModuleFile :: [FilePath] -> [String] -> ModuleName -> IO (FilePath, FilePath)
- findModuleFiles :: [FilePath] -> [String] -> [ModuleName] -> IO [(FilePath, FilePath)]
- getDirectoryContentsRecursive :: FilePath -> IO [FilePath]
- isInSearchPath :: FilePath -> NoCallStackIO Bool
- addLibraryPath :: OS -> [FilePath] -> [(String, String)] -> [(String, String)]
- matchFileGlob :: FilePath -> IO [FilePath]
- matchDirFileGlob :: FilePath -> FilePath -> IO [FilePath]
- parseFileGlob :: FilePath -> Maybe FileGlob
- data FileGlob
  - = NoGlob FilePath
  - | FileGlob FilePath String
- moreRecentFile :: FilePath -> FilePath -> NoCallStackIO Bool
- existsAndIsMoreRecentThan :: FilePath -> FilePath -> NoCallStackIO Bool
- data TempFileOptions = TempFileOptions {
  - optKeepTempFiles :: Bool
  }
- defaultTempFileOptions :: TempFileOptions
- withTempFile :: FilePath -> String -> (FilePath -> Handle -> IO a) -> IO a
- withTempFileEx :: TempFileOptions -> FilePath -> String -> (FilePath -> Handle -> IO a) -> IO a
- withTempDirectory :: Verbosity -> FilePath -> String -> (FilePath -> IO a) -> IO a
- withTempDirectoryEx :: Verbosity -> TempFileOptions -> FilePath -> String -> (FilePath -> IO a) -> IO a
- defaultPackageDesc :: Verbosity -> IO FilePath
- findPackageDesc :: FilePath -> NoCallStackIO (Either String FilePath)
- tryFindPackageDesc :: FilePath -> IO FilePath
- defaultHookedPackageDesc :: IO (Maybe FilePath)
- findHookedPackageDesc :: FilePath -> IO (Maybe FilePath)
- withFileContents :: FilePath -> (String -> NoCallStackIO a) -> NoCallStackIO a
- writeFileAtomic :: FilePath -> ByteString -> NoCallStackIO ()
- rewriteFile :: FilePath -> String -> IO ()
- rewriteFileEx :: Verbosity -> FilePath -> String -> IO ()
- fromUTF8 :: String -> String
- fromUTF8BS :: ByteString -> String
- fromUTF8LBS :: ByteString -> String
- toUTF8 :: String -> String
- readUTF8File :: FilePath -> NoCallStackIO String
- withUTF8FileContents :: FilePath -> (String -> IO a) -> IO a
- writeUTF8File :: FilePath -> String -> NoCallStackIO ()
- normaliseLineEndings :: String -> String
- startsWithBOM :: String -> Bool
- fileHasBOM :: FilePath -> NoCallStackIO Bool
- ignoreBOM :: String -> String
- dropWhileEndLE :: (a -> Bool) -> [a] -> [a]
- takeWhileEndLE :: (a -> Bool) -> [a] -> [a]
- equating :: Eq a => (b -> a) -> b -> b -> Bool
- comparing :: Ord a => (b -> a) -> b -> b -> Ordering
- isInfixOf :: Eq a => [a] -> [a] -> Bool
- intercalate :: [a] -> [[a]] -> [a]
- lowercase :: String -> String
- listUnion :: Ord a => [a] -> [a] -> [a]
- listUnionRight :: Ord a => [a] -> [a] -> [a]
- ordNub :: Ord a => [a] -> [a]
- ordNubBy :: Ord b => (a -> b) -> [a] -> [a]
- ordNubRight :: Ord a => [a] -> [a]
- safeTail :: [a] -> [a]
- unintersperse :: Char -> String -> [String]
- wrapText :: String -> String
- wrapLine :: Int -> [String] -> [[String]]
- isAbsoluteOnAnyPlatform :: FilePath -> Bool
- isRelativeOnAnyPlatform :: FilePath -> Bool

# Documentation

cabalVersion :: Version #

# logging and errors

die :: String -> IO a #

Deprecated: Messages thrown with die can't be controlled with Verbosity; use die' instead, or dieNoVerbosity if Verbosity truly is not available

dieWithLocation :: FilePath -> Maybe Int -> String -> IO a #

Deprecated: Messages thrown with dieWithLocation can't be controlled with Verbosity; use dieWithLocation' instead

dieNoVerbosity :: String -> IO a #

die' :: Verbosity -> String -> IO a #

dieWithLocation' :: Verbosity -> FilePath -> Maybe Int -> String -> IO a #

dieNoWrap :: Verbosity -> String -> IO a #

topHandler :: IO a -> IO a #

topHandlerWith :: forall a. (SomeException -> IO a) -> IO a -> IO a #

warn :: Verbosity -> String -> IO () #

Non fatal conditions that may be indicative of an error or problem.

We display these at the `normal` verbosity level.

notice :: Verbosity -> String -> IO () #

Useful status messages.

We display these at the `normal` verbosity level.

This is for the ordinary helpful status messages that users see. Just enough information to know that things are working but not floods of detail.

noticeNoWrap :: Verbosity -> String -> IO () #

Display a message at `normal` verbosity level, but without wrapping.

noticeDoc :: Verbosity -> Doc -> IO () #

Pretty-print a `Doc` status message at `normal` verbosity level. Use this if you need fancy formatting.

setupMessage :: Verbosity -> String -> PackageIdentifier -> IO () #

Display a "setup status message". Prefer using setupMessage' if possible.

info :: Verbosity -> String -> IO () #

More detail on the operation of some action.

We display these messages when the verbosity level is `verbose`

infoNoWrap :: Verbosity -> String -> IO () #

debug :: Verbosity -> String -> IO () #

Detailed internal debugging information

We display these messages when the verbosity level is `deafening`

debugNoWrap :: Verbosity -> String -> IO () #

A variant of `debug` that doesn't perform the automatic line wrapping. Produces better output in some cases.

chattyTry #

Arguments

:: String | a description of the action we were attempting
-> IO () | the action itself
-> IO () |

Perform an IO action, catching any IO exceptions and printing an error if one occurs.

annotateIO :: Verbosity -> IO a -> IO a #

Given a block of IO code that may raise an exception, annotate it with the metadata from the current scope. Use this as close to external code that raises IO exceptions as possible, since this function unconditionally wraps the error message with a trace (so it is NOT idempotent.)

printRawCommandAndArgs :: Verbosity -> FilePath -> [String] -> IO () #

printRawCommandAndArgsAndEnv :: Verbosity -> FilePath -> [String] -> Maybe FilePath -> Maybe [(String, String)] -> IO () #

# exceptions

handleDoesNotExist :: a -> NoCallStackIO a -> NoCallStackIO a #

Run an IO computation, returning `e` if it raises a "file does not exist" error.

# running programs

rawSystemExit :: Verbosity -> FilePath -> [String] -> IO () #

rawSystemExitCode :: Verbosity -> FilePath -> [String] -> IO ExitCode #

rawSystemExitWithEnv :: Verbosity -> FilePath -> [String] -> [(String, String)] -> IO () #

rawSystemStdout :: Verbosity -> FilePath -> [String] -> IO String #

Run a command and return its output.

The output is assumed to be text in the locale encoding.

rawSystemStdInOut #

Arguments

:: Verbosity |
-> FilePath | Program location
-> [String] | Arguments
-> Maybe FilePath | New working dir or inherit
-> Maybe [(String, String)] | New environment or inherit
-> Maybe (String, Bool) | input text and binary mode
-> Bool | output in binary mode
-> IO (String, String, ExitCode) | output, errors, exit

Run a command and return its output, errors and exit status. Optionally also supply some input. Also provides control over whether the binary/text mode of the input and output.

rawSystemIOWithEnv #

Arguments

:: Verbosity |
-> FilePath |
-> [String] |
-> Maybe FilePath | New working dir or inherit
-> Maybe [(String, String)] | New environment or inherit
-> Maybe Handle | stdin
-> Maybe Handle | stdout
-> Maybe Handle | stderr
-> IO ExitCode |

createProcessWithEnv #

Arguments

:: Verbosity |
-> FilePath |
-> [String] |
-> Maybe FilePath | New working dir or inherit
-> Maybe [(String, String)] | New environment or inherit
-> StdStream | stdin
-> StdStream | stdout
-> StdStream | stderr
-> IO (Maybe Handle, Maybe Handle, Maybe Handle, ProcessHandle) | Any handles created for stdin, stdout, or stderr with `CreateProcess`, and a handle to the process.

maybeExit :: IO ExitCode -> IO () #

xargs :: Int -> ([String] -> IO ()) -> [String] -> [String] -> IO () #

Like the Unix xargs program. Useful for when we've got very long command lines that might overflow an OS limit on command line length and so you need to invoke a command multiple times to get all the args in.

Use it with either of the rawSystem variants above. For example:

    xargs (32*1024) (rawSystemExit verbosity) prog fixedArgs bigArgs

findProgramLocation :: Verbosity -> FilePath -> IO (Maybe FilePath) #

Deprecated: No longer used within Cabal, try findProgramOnSearchPath

Look for a program on the path.

findProgramVersion #

Arguments

:: String | version args
-> (String -> String) | function to select version number from program output
-> Verbosity |
-> FilePath | location
-> IO (Maybe Version) |

Look for a program and try to find it's version number. It can accept either an absolute path or the name of a program binary, in which case we will look for the program on the path.

# copying files

smartCopySources :: Verbosity -> [FilePath] -> FilePath -> [ModuleName] -> [String] -> IO () #

Deprecated: Use findModuleFiles and copyFiles or installOrdinaryFiles

createDirectoryIfMissingVerbose #

Arguments

:: Verbosity |
-> Bool | Create its parents too?
-> FilePath |
-> IO () |

Same as `createDirectoryIfMissing` but logs at higher verbosity levels.

copyFileVerbose :: Verbosity -> FilePath -> FilePath -> IO () #

Copies a file without copying file permissions. The target file is created with default permissions. Any existing target file is replaced.

At higher verbosity levels it logs an info message.

copyDirectoryRecursiveVerbose :: Verbosity -> FilePath -> FilePath -> IO () #

Deprecated: You probably want installDirectoryContents instead

copyFiles :: Verbosity -> FilePath -> [(FilePath, FilePath)] -> IO () #

Copies a bunch of files to a target directory, preserving the directory structure in the target location. The target directories are created if they do not exist.

The files are identified by a pair of base directory and a path relative to that base. It is only the relative part that is preserved in the destination.

For example:

    copyFiles normal "dist/src"
       [("", "src/Foo.hs"), ("dist/build/", "src/Bar.hs")]

This would copy "src/Foo.hs" to "dist/src/src/Foo.hs" and copy "dist/build/src/Bar.hs" to "dist/src/src/Bar.hs".

This operation is not atomic. Any IO failure during the copy (including any missing source files) leaves the target in an unknown state so it is best to use it with a freshly created directory so that it can be simply deleted if anything goes wrong.

copyFileTo :: Verbosity -> FilePath -> FilePath -> IO () #

Given a relative path to a file, copy it to the given directory, preserving the relative path and creating the parent directories if needed.

# installing files

installOrdinaryFile :: Verbosity -> FilePath -> FilePath -> IO () #

Install an ordinary file. This is like a file copy but the permissions are set appropriately for an installed file. On Unix it is "-rw-r--r--" while on Windows it uses the default permissions for the target directory.

installExecutableFile :: Verbosity -> FilePath -> FilePath -> IO () #

Install an executable file. This is like a file copy but the permissions are set appropriately for an installed file. On Unix it is "-rwxr-xr-x" while on Windows it uses the default permissions for the target directory.

installMaybeExecutableFile :: Verbosity -> FilePath -> FilePath -> IO () #

Install a file that may or not be executable, preserving permissions.

installOrdinaryFiles :: Verbosity -> FilePath -> [(FilePath, FilePath)] -> IO () #

This is like `copyFiles` but uses `installOrdinaryFile`.

installExecutableFiles :: Verbosity -> FilePath -> [(FilePath, FilePath)] -> IO () #

This is like `copyFiles` but uses `installExecutableFile`.

installMaybeExecutableFiles :: Verbosity -> FilePath -> [(FilePath, FilePath)] -> IO () #

This is like `copyFiles` but uses `installMaybeExecutableFile`.

installDirectoryContents :: Verbosity -> FilePath -> FilePath -> IO () #

This installs all the files in a directory to a target location, preserving the directory layout. All the files are assumed to be ordinary rather than executable files.

copyDirectoryRecursive :: Verbosity -> FilePath -> FilePath -> IO () #

Recursively copy the contents of one directory to another path.

# File permissions

doesExecutableExist :: FilePath -> NoCallStackIO Bool #

Like `doesFileExist`, but also checks that the file is executable.

setFileOrdinary :: FilePath -> NoCallStackIO () #

setFileExecutable :: FilePath -> NoCallStackIO () #

# file names

currentDir :: FilePath #

The path name that represents the current directory. In Unix, it's `"."`, but this is system-specific. (E.g. AmigaOS uses the empty string `""` for the current directory.)

shortRelativePath :: FilePath -> FilePath -> FilePath #

dropExeExtension :: FilePath -> FilePath #

Drop the extension if it's one of `exeExtensions`, or return the path unchanged.

exeExtensions :: [String] #

List of possible executable file extensions on the current platform.

# finding files

findFile #

Arguments

:: [FilePath] | search locations
-> FilePath | File Name
-> IO FilePath |

Find a file by looking in a search path. The file path must match exactly.

findFirstFile :: (a -> FilePath) -> [a] -> NoCallStackIO (Maybe a) #

findFileWithExtension :: [String] -> [FilePath] -> FilePath -> NoCallStackIO (Maybe FilePath) #

Find a file by looking in a search path with one of a list of possible file extensions. The file base name should be given and it will be tried with each of the extensions in each element of the search path.

findFileWithExtension' :: [String] -> [FilePath] -> FilePath -> NoCallStackIO (Maybe (FilePath, FilePath)) #

Like `findFileWithExtension` but returns which element of the search path the file was found in, and the file path relative to that base directory.

findAllFilesWithExtension :: [String] -> [FilePath] -> FilePath -> NoCallStackIO [FilePath] #

findModuleFile #

Arguments

:: [FilePath] | build prefix (location of objects)
-> [String] | search suffixes
-> ModuleName | module
-> IO (FilePath, FilePath) |

Find the file corresponding to a Haskell module name.

This is similar to `findFileWithExtension'` but specialised to a module name. The function fails if the file corresponding to the module is missing.

findModuleFiles #

Arguments

:: [FilePath] | build prefix (location of objects)
-> [String] | search suffixes
-> [ModuleName] | modules
-> IO [(FilePath, FilePath)] |

Finds the files corresponding to a list of Haskell module names.

As `findModuleFile` but for a list of module names.

getDirectoryContentsRecursive :: FilePath -> IO [FilePath] #

List all the files in a directory and all subdirectories.

The order places files in sub-directories after all the files in their parent directories. The list is generated lazily so is not well defined if the source directory structure changes before the list is used.

# environment variables

isInSearchPath :: FilePath -> NoCallStackIO Bool #

Is this directory in the system search path?

addLibraryPath :: OS -> [FilePath] -> [(String, String)] -> [(String, String)] #

# simple file globbing

matchFileGlob :: FilePath -> IO [FilePath] #

matchDirFileGlob :: FilePath -> FilePath -> IO [FilePath] #

parseFileGlob :: FilePath -> Maybe FileGlob #

data FileGlob #

Constructors

NoGlob FilePath | No glob at all, just an ordinary file
FileGlob FilePath String | dir prefix and extension, like `"foo/bar/*.baz"` corresponds to `FileGlob "foo/bar" ".baz"`

# modification time

moreRecentFile :: FilePath -> FilePath -> NoCallStackIO Bool #

Compare the modification times of two files to see if the first is newer than the second. The first file must exist but the second need not. The expected use case is when the second file is generated using the first. In this use case, if the result is True then the second file is out of date.

existsAndIsMoreRecentThan :: FilePath -> FilePath -> NoCallStackIO Bool #

Like `moreRecentFile`, but also checks that the first file exists.

# temp files and dirs

data TempFileOptions #

Advanced options for `withTempFile` and `withTempDirectory`.

Constructors

TempFileOptions |

Fields

- optKeepTempFiles :: Bool

  Keep temporary files?

defaultTempFileOptions :: TempFileOptions #

withTempFile #

Arguments

:: FilePath | Temp dir to create the file in
-> String | File name template. See `openTempFile`.
-> (FilePath -> Handle -> IO a) |
-> IO a |

Use a temporary filename that doesn't already exist.

withTempFileEx #

Arguments

:: TempFileOptions |
-> FilePath | Temp dir to create the file in
-> String | File name template. See `openTempFile`.
-> (FilePath -> Handle -> IO a) |
-> IO a |

A version of `withTempFile` that additionally takes a `TempFileOptions` argument.

withTempDirectory :: Verbosity -> FilePath -> String -> (FilePath -> IO a) -> IO a #

Create and use a temporary directory.

Creates a new temporary directory inside the given directory, making use of the template. The temp directory is deleted after use. For example:

    withTempDirectory verbosity "src" "sdist." $ \tmpDir -> do ...

The `tmpDir` will be a new subdirectory of the given directory, e.g. `src/sdist.342`.

withTempDirectoryEx :: Verbosity -> TempFileOptions -> FilePath -> String -> (FilePath -> IO a) -> IO a #

A version of `withTempDirectory` that additionally takes a `TempFileOptions` argument.

# .cabal and .buildinfo files

defaultPackageDesc :: Verbosity -> IO FilePath #

Package description file (pkgname`.cabal`)

findPackageDesc #

Arguments

:: FilePath | Where to look
-> NoCallStackIO (Either String FilePath) | pkgname.cabal

Find a package description file in the given directory. Looks for `.cabal` files.

tryFindPackageDesc :: FilePath -> IO FilePath #

Like `findPackageDesc`, but calls `die` in case of error.

defaultHookedPackageDesc :: IO (Maybe FilePath) #

Optional auxiliary package information file (pkgname`.buildinfo`)

findHookedPackageDesc #

Arguments

:: FilePath | Directory to search
-> IO (Maybe FilePath) | dir`/`pkgname`.buildinfo`, if present

Find auxiliary package information in the given directory. Looks for `.buildinfo` files.

# reading and writing files safely

withFileContents :: FilePath -> (String -> NoCallStackIO a) -> NoCallStackIO a #

Gets the contents of a file, but guarantee that it gets closed.

The file is read lazily but if it is not fully consumed by the action then the remaining input is truncated and the file is closed.

writeFileAtomic :: FilePath -> ByteString -> NoCallStackIO () #

Writes a file atomically.

The file is either written successfully or an IO exception is raised and the original file is left unchanged.

On windows it is not possible to delete a file that is open by a process. This case will give an IO exception but the atomic property is not affected.

rewriteFile :: FilePath -> String -> IO () #

See `rewriteFileEx`

This function is provided for backwards-compatibility

rewriteFileEx :: Verbosity -> FilePath -> String -> IO () #

Write a file but only if it would have new content. If we would be writing the same as the existing content then leave the file as is so that we do not update the file's modification time.

NB: the file is assumed to be ASCII-encoded.

# Unicode

fromUTF8 :: String -> String #

fromUTF8BS :: ByteString -> String #

fromUTF8LBS :: ByteString -> String #

toUTF8 :: String -> String #

readUTF8File :: FilePath -> NoCallStackIO String #

Reads a UTF8 encoded text file as a Unicode String

Reads lazily using ordinary `readFile`.

withUTF8FileContents :: FilePath -> (String -> IO a) -> IO a #

Reads a UTF8 encoded text file as a Unicode String

Same behaviour as `withFileContents`.

writeUTF8File :: FilePath -> String -> NoCallStackIO () #

Writes a Unicode String as a UTF8 encoded text file.

Uses `writeFileAtomic`, so provides the same guarantees.

normaliseLineEndings :: String -> String #

Fix different systems silly line ending conventions

# BOM

startsWithBOM :: String -> Bool #

Whether BOM is at the beginning of the input

fileHasBOM :: FilePath -> NoCallStackIO Bool #

Check whether a file has Unicode byte order mark (BOM).

ignoreBOM :: String -> String #

Ignore a Unicode byte order mark (BOM) at the beginning of the input

# generic utils

dropWhileEndLE :: (a -> Bool) -> [a] -> [a] #

`dropWhileEndLE p` is equivalent to `reverse . dropWhile p . reverse`, but quite a bit faster. The difference between "Data.List.dropWhileEnd" and this version is that the one in Data.List is strict in elements, but spine-lazy, while this one is spine-strict but lazy in elements. That's what `LE` stands for - "lazy in elements".

Example:

    > tail $ Data.List.dropWhileEnd (<3) [undefined, 5, 4, 3, 2, 1]
    *** Exception: Prelude.undefined
    > tail $ dropWhileEndLE (<3) [undefined, 5, 4, 3, 2, 1]
    [5,4,3]
    > take 3 $ Data.List.dropWhileEnd (<3) [5, 4, 3, 2, 1, undefined]
    [5,4,3]
    > take 3 $ dropWhileEndLE (<3) [5, 4, 3, 2, 1, undefined]
    *** Exception: Prelude.undefined

takeWhileEndLE :: (a -> Bool) -> [a] -> [a] #

`takeWhileEndLE p` is equivalent to `reverse . takeWhile p . reverse`, but is usually faster (as well as being easier to read).

equating :: Eq a => (b -> a) -> b -> b -> Bool #

comparing :: Ord a => (b -> a) -> b -> b -> Ordering Source #

    comparing p x y = compare (p x) (p y)

Useful combinator for use in conjunction with the `xxxBy` family of functions from Data.List, for example:

      ... sortBy (comparing fst) ...

isInfixOf :: Eq a => [a] -> [a] -> Bool Source #

The `isInfixOf` function takes two lists and returns `True` iff the first list is contained, wholly and intact, anywhere within the second.

Example:

    isInfixOf "Haskell" "I really like Haskell." == True
    isInfixOf "Ial" "I really like Haskell." == False

intercalate :: [a] -> [[a]] -> [a] Source #

`intercalate` `xs xss` is equivalent to `(`concat` (`intersperse` xs xss))`. It inserts the list `xs` in between the lists in `xss` and concatenates the result.

lowercase :: String -> String #

listUnion :: Ord a => [a] -> [a] -> [a] #

Like "Data.List.union", but has `O(n log n)` complexity instead of `O(n^2)`.

listUnionRight :: Ord a => [a] -> [a] -> [a] #

A right-biased version of `listUnion`.

Example:

    > listUnion [1,2,3,4,3] [2,1,1]
    [1,2,3,4,3]
    > listUnionRight [1,2,3,4,3] [2,1,1]
    [4,3,2,1,1]

ordNub :: Ord a => [a] -> [a] #

Like `nub`, but has `O(n log n)` complexity instead of `O(n^2)`. Code for `ordNub` and `listUnion` taken from Niklas Hambüchen's ordnub package.

ordNubBy :: Ord b => (a -> b) -> [a] -> [a] #

Like `ordNub` and `nubBy`. Selects a key for each element and takes the nub based on that key.

ordNubRight :: Ord a => [a] -> [a] #

A right-biased version of `ordNub`.

Example:

    > ordNub [1,2,1]
    [1,2]
    > ordNubRight [1,2,1]
    [2,1]

safeTail :: [a] -> [a] #

A total variant of `tail`.

unintersperse :: Char -> String -> [String] #

wrapText :: String -> String #

Wraps text to the default line width. Existing newlines are preserved.

wrapLine :: Int -> [String] -> [[String]] #

Wraps a list of words to a list of lines of words of a particular width.

# FilePath stuff

isAbsoluteOnAnyPlatform :: FilePath -> Bool #

`isAbsoluteOnAnyPlatform` and `isRelativeOnAnyPlatform` are like `isAbsolute` and `isRelative` but have platform independent heuristics. The System.FilePath exists in two versions, Windows and Posix. The two versions don't agree on what is a relative path and we don't know if we're given Windows or Posix paths. This results in false positives when running on Posix and inspecting Windows paths, like the hackage server does. System.FilePath.Posix.isAbsolute "C:\hello" == False System.FilePath.Windows.isAbsolute "/hello" == False This means that we would treat paths that start with "/" to be absolute. On Posix they are indeed absolute, while on Windows they are not.

The portable versions should be used when we might deal with paths that are from another OS than the host OS. For example, the Hackage Server deals with both Windows and Posix paths while performing the PackageDescription checks. In contrast, when we run 'cabal configure' we do expect the paths to be correct for our OS and we should not have to use the platform independent heuristics.

isRelativeOnAnyPlatform :: FilePath -> Bool #

    isRelativeOnAnyPlatform = not . isAbsoluteOnAnyPlatform