Cabal-1.14.0: A framework for packaging Haskell software

Safe HaskellSafe-Infered




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.



logging and errors

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

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

We display these at the normal verbosity level.

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

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.

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

More detail on the operation of some action.

We display these messages when the verbosity level is verbose

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

Detailed internal debugging information

We display these messages when the verbosity level is deafening



:: 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.

running programs

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

Run a command and return its output.

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



:: Verbosity 
-> FilePath 
-> [String] 
-> 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.

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

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)Source

Look for a program on the path.



:: String

version args

-> (String -> String)

function to select version number from program output

-> Verbosity 
-> FilePath


-> 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



:: Verbosity 
-> Bool

Create its parents too?

-> FilePath 
-> IO () 

Same as createDirectoryIfMissing but logs at higher verbosity levels.

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

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.

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

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.

installing files

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

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 ()Source

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.

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

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.

File permissions

file names

currentDir :: FilePathSource

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.)

finding files



:: [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] -> IO (Maybe a)Source

findFileWithExtension :: [String] -> [FilePath] -> FilePath -> IO (Maybe FilePath)Source

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 -> IO (Maybe (FilePath, FilePath))Source

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



:: [FilePath]

build prefix (location of objects)

-> [String]

search suffixes

-> ModuleName


-> 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.



:: [FilePath]

build prefix (location of objects)

-> [String]

search suffixes

-> [ModuleName]


-> 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]Source

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.

simple file globbing

data FileGlob Source


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"

temp files and dirs



:: 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.

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

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.

.cabal and .buildinfo files

defaultPackageDesc :: Verbosity -> IO FilePathSource

Package description file (pkgname.cabal)



:: FilePath

Where to look

-> IO FilePath


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

defaultHookedPackageDesc :: IO (Maybe FilePath)Source

Optional auxiliary package information file (pkgname.buildinfo)



:: 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 -> IO a) -> IO aSource

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 -> String -> IO ()Source

Writes a file atomically.

The file is either written sucessfully 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 ()Source

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.


readUTF8File :: FilePath -> IO StringSource

Reads a UTF8 encoded text file as a Unicode String

Reads lazily using ordinary readFile.

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

Reads a UTF8 encoded text file as a Unicode String

Same behaviour as withFileContents.

writeUTF8File :: FilePath -> String -> IO ()Source

Writes a Unicode String as a UTF8 encoded text file.

Uses writeFileAtomic, so provides the same guarantees.

normaliseLineEndings :: String -> StringSource

Fix different systems silly line ending conventions

generic utils

equating :: Eq a => (b -> a) -> b -> b -> BoolSource

comparing :: Ord a => (b -> a) -> b -> b -> OrderingSource

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

wrapText :: String -> StringSource

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

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

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