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GHC 9.10.3 · lts/ghc-9.10.x · 248f8f0 · 2026-10-05

ModuleCabal-3.12.1.0Haskell2010

Distribution.Simple.InstallDirs

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.

  • 6 types
  • 16 values
  • PackageCabal-3.12.1.0
  • Exports22
  • LanguageHaskell2010
  • LicenceBSD-3-Clause
  • SourceInstallDirs.hs
datadata InstallDirs dir
#

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 directories. This is particularly the case on Unix style systems.

Constructors

Instances10Functor, Eq, Read, Show, Generic, Semigroup, …
typetype InstallDirTemplates = InstallDirs PathTemplate
#

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 substitution (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/$libname/$compiler.

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

datadata CopyDest
#

The location prefix for the copy command.

Constructors

Instances6Eq, Show, Generic, Binary, Structured, Rep
valuesubstituteInstallDirTemplates
  1. :: PathTemplateEnv
  2. -> InstallDirTemplates
  3. -> InstallDirTemplates
#

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.

newtypenewtype PathTemplate
#

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

Instances8Eq, Ord, Read, Show, Generic, Binary, …
datadata PathTemplateVariable
#

Constructors

Instances8Eq, Ord, Read, Show, Generic, Binary, …