Cabal- A framework for packaging Haskell software

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This manages everything to do with where files get installed (though does not get involved with actually doing any installation). It provides an InstallDirs type which is a set of directories for where to install things. It also handles the fact that we use templates in these install dirs. For example most install dirs are relative to some $prefix and by changing the prefix all other dirs still end up changed appropriately. So it provides a PathTemplate type and functions for substituting for these templates.



data InstallDirs dir Source

The directories where we will install files for packages.

We have several different directories for different types of files since many systems have conventions whereby different types of files in a package are installed in different direcotries. This is particularly the case on unix style systems.




prefix :: dir
bindir :: dir
libdir :: dir
libsubdir :: dir
dynlibdir :: dir
libexecdir :: dir
progdir :: dir
includedir :: dir
datadir :: dir
datasubdir :: dir
docdir :: dir
mandir :: dir
htmldir :: dir
haddockdir :: dir


Functor InstallDirs 
Read dir => Read (InstallDirs dir) 
Show dir => Show (InstallDirs dir) 
Monoid dir => Monoid (InstallDirs dir) 

type InstallDirTemplates = InstallDirs PathTemplateSource

The installation directories in terms of PathTemplates that contain variables.

The defaults for most of the directories are relative to each other, in particular they are all relative to a single prefix. This makes it convenient for the user to override the default installation directory by only having to specify --prefix=... rather than overriding each individually. This is done by allowing $-style variables in the dirs. These are expanded by textual substituion (see substPathTemplate).

A few of these installation directories are split into two components, the dir and subdir. The full installation path is formed by combining the two together with /. The reason for this is compatibility with other unix build systems which also support --libdir and --datadir. We would like users to be able to configure --libdir=/usr/lib64 for example but because by default we want to support installing multiple versions of packages and building the same package for multiple compilers we append the libsubdir to get: /usr/lib64/$pkgid/$compiler.

An additional complication is the need to support relocatable packages on systems which support such things, like Windows.

absoluteInstallDirs :: PackageIdentifier -> CompilerId -> CopyDest -> InstallDirs PathTemplate -> InstallDirs FilePathSource

Convert from abstract install directories to actual absolute ones by substituting for all the variables in the abstract paths, to get real absolute path.

data CopyDest Source

The location prefix for the copy command.


CopyTo FilePath 


prefixRelativeInstallDirs :: PackageIdentifier -> CompilerId -> InstallDirTemplates -> InstallDirs (Maybe FilePath)Source

Check which of the paths are relative to the installation $prefix.

If any of the paths are not relative, ie they are absolute paths, then it prevents us from making a relocatable package (also known as a "prefix independent" package).

substituteInstallDirTemplates :: PathTemplateEnv -> InstallDirTemplates -> InstallDirTemplatesSource

Substitute the install dir templates into each other.

To prevent cyclic substitutions, only some variables are allowed in particular dir templates. If out of scope vars are present, they are not substituted for. Checking for any remaining unsubstituted vars can be done as a subsequent operation.

The reason it is done this way is so that in prefixRelativeInstallDirs we can replace prefix with the PrefixVar and get resulting PathTemplates that still have the PrefixVar in them. Doing this makes it each to check which paths are relative to the $prefix.

data PathTemplate Source

An abstract path, posibly containing variables that need to be substituted for to get a real FilePath.

data PathTemplateVariable Source



The $prefix path variable


The $bindir path variable


The $libdir path variable


The $libsubdir path variable


The $datadir path variable


The $datasubdir path variable


The $docdir path variable


The $htmldir path variable


The $pkg package name path variable


The $version package version path variable


The $pkgid package Id path variable, eg foo-1.0


The compiler name and version, eg ghc-6.6.1


The operating system name, eg windows or linux


The cpu architecture name, eg i386 or x86_64


The executable name; used in shell wrappers


The name of the test suite being run


The result of the test suite being run, eg pass, fail, or error.


The name of the benchmark being run

toPathTemplate :: FilePath -> PathTemplateSource

Convert a FilePath to a PathTemplate including any template vars.

fromPathTemplate :: PathTemplate -> FilePathSource

Convert back to a path, any remaining vars are included

initialPathTemplateEnv :: PackageIdentifier -> CompilerId -> PathTemplateEnvSource

The initial environment has all the static stuff but no paths