2.1. Configuration¶

2.1.1. Overview¶

The global configuration file for cabal-install is ~/.cabal/config. If you do not have this file, cabal will create it for you on the first call to cabal update. Alternatively, you can explicitly ask cabal to create it for you using

$ cabal user-config update

Most of the options in this configuration file are also available as command line arguments, and the corresponding documentation can be used to lookup their meaning. The created configuration file only specifies values for a handful of options. Most options are left at their default value, which it documents; for instance,

-- executable-stripping: True

means that the configuration file currently does not specify a value for the executable-stripping option (the line is commented out), and that the default is True; if you wanted to disable stripping of executables by default, you would change this line to

executable-stripping: False

You can also use cabal user-config update to migrate configuration files created by older versions of cabal.

2.1.2. Repository specification¶

An important part of the configuration if the specification of the repository. When cabal creates a default config file, it configures the repository to be the central Hackage server:

repository hackage.haskell.org
  url: http://hackage.haskell.org/

The name of the repository is given on the first line, and can be anything; packages downloaded from this repository will be cached under ~/.cabal/packages/hackage.haskell.org (or whatever name you specify; you can change the prefix by changing the value of remote-repo-cache). If you want, you can configure multiple repositories, and cabal will combine them and be able to download packages from any of them.

2.1.2.1. Using secure repositories¶

For repositories that support the TUF security infrastructure (this includes Hackage), you can enable secure access to the repository by specifying:

repository hackage.haskell.org
  url: http://hackage.haskell.org/
  secure: True
  root-keys: <root-key-IDs>
  key-threshold: <key-threshold>

The <root-key-IDs> and <key-threshold> values are used for bootstrapping. As part of the TUF infrastructure the repository will contain a file root.json (for instance, http://hackage.haskell.org/root.json) which the client needs to do verification. However, how can cabal verify the root.json file itself? This is known as bootstrapping: if you specify a list of root key IDs and a corresponding threshold, cabal will verify that the downloaded root.json file has been signed with at least <key-threshold> keys from your set of <root-key-IDs>.

You can, but are not recommended to, omit these two fields. In that case cabal will download the root.json field and use it without verification. Although this bootstrapping step is then unsafe, all subsequent access is secure (provided that the downloaded root.json was not tempered with). Of course, adding root-keys and key-threshold to your repository specification only shifts the problem, because now you somehow need to make sure that the key IDs you received were the right ones. How that is done is however outside the scope of cabal proper.

More information about the security infrastructure can be found at https://github.com/well-typed/hackage-security.

2.1.2.2. Legacy repositories¶

Currently cabal supports two kinds of “legacy” repositories. The first is specified using

remote-repo: hackage.haskell.org:http://hackage.haskell.org/packages/archive

This is just syntactic sugar for

repository hackage.haskell.org
  url: hackage.haskell.org:http://hackage.haskell.org/packages/archive

although, in (and only in) the specific case of Hackage, the URL http://hackage.haskell.org/packages/archive will be silently translated to http://hackage.haskell.org/.

The second kind of legacy repositories are so-called “local” repositories:

local-repo: my-local-repo:/path/to/local/repo

This can be used to access repositories on the local file system. However, the layout of these local repositories is different from the layout of remote repositories, and usage of these local repositories is deprecated.

2.1.2.3. Secure local repositories¶

If you want to use repositories on your local file system, it is recommended instead to use a secure local repository:

repository my-local-repo
  url: file:/path/to/local/repo
  secure: True
  root-keys: <root-key-IDs>
  key-threshold: <key-threshold>

The layout of these secure local repos matches the layout of remote repositories exactly; the hackage-repo-tool can be used to create and manage such repositories.

2.2. Building and installing packages¶

After you’ve unpacked a Cabal package, you can build it by moving into the root directory of the package and running the cabal tool there:

$ cabal [command] [option...]

The command argument selects a particular step in the build/install process.

You can also get a summary of the command syntax with

$ cabal help

Alternatively, you can also use the Setup.hs or Setup.lhs script:

$ runhaskell Setup.hs [command] [option...]

For the summary of the command syntax, run:

$ cabal help

or

$ runhaskell Setup.hs --help

2.2.1. Building and installing a system package¶

$ runhaskell Setup.hs configure --ghc
$ runhaskell Setup.hs build
$ runhaskell Setup.hs install

The first line readies the system to build the tool using GHC; for example, it checks that GHC exists on the system. The second line performs the actual building, while the last both copies the build results to some permanent place and registers the package with GHC.

2.2.2. Building and installing a user package¶

$ runhaskell Setup.hs configure --user
$ runhaskell Setup.hs build
$ runhaskell Setup.hs install

The package is installed under the user’s home directory and is registered in the user’s package database (setup configure --user).

2.2.3. Installing packages from Hackage¶

The cabal tool also can download, configure, build and install a Hackage package and all of its dependencies in a single step. To do this, run:

$ cabal install [PACKAGE...]

To browse the list of available packages, visit the Hackage web site.

2.2.4. Developing with sandboxes¶

By default, any dependencies of the package are installed into the global or user package databases (e.g. using cabal install --only-dependencies). If you’re building several different packages that have incompatible dependencies, this can cause the build to fail. One way to avoid this problem is to build each package in an isolated environment (“sandbox”), with a sandbox-local package database. Because sandboxes are per-project, inconsistent dependencies can be simply disallowed.

For more on sandboxes, see also this article.

2.2.4.1. Sandboxes: basic usage¶

To initialise a fresh sandbox in the current directory, run cabal sandbox init. All subsequent commands (such as build and install) from this point will use the sandbox.

$ cd /path/to/my/haskell/library
$ cabal sandbox init                   # Initialise the sandbox
$ cabal install --only-dependencies    # Install dependencies into the sandbox
$ cabal build                          # Build your package inside the sandbox

It can be useful to make a source package available for installation in the sandbox - for example, if your package depends on a patched or an unreleased version of a library. This can be done with the cabal sandbox add-source command - think of it as “local Hackage”. If an add-source dependency is later modified, it is reinstalled automatically.

$ cabal sandbox add-source /my/patched/library # Add a new add-source dependency
$ cabal install --dependencies-only            # Install it into the sandbox
$ cabal build                                  # Build the local package
$ $EDITOR /my/patched/library/Source.hs        # Modify the add-source dependency
$ cabal build                                  # Modified dependency is automatically reinstalled

Normally, the sandbox settings (such as optimisation level) are inherited from the main Cabal config file ($HOME/cabal/config). Sometimes, though, you need to change some settings specifically for a single sandbox. You can do this by creating a cabal.config file in the same directory with your cabal.sandbox.config (which was created by sandbox init). This file has the same syntax as the main Cabal config file.

$ cat cabal.config
documentation: True
constraints: foo == 1.0, bar >= 2.0, baz
$ cabal build                                  # Uses settings from the cabal.config file

When you have decided that you no longer want to build your package inside a sandbox, just delete it:

$ cabal sandbox delete                       # Built-in command
$ rm -rf .cabal-sandbox cabal.sandbox.config # Alternative manual method

2.2.4.2. Sandboxes: advanced usage¶

The default behaviour of the add-source command is to track modifications done to the added dependency and reinstall the sandbox copy of the package when needed. Sometimes this is not desirable: in these cases you can use add-source --snapshot, which disables the change tracking. In addition to add-source, there are also list-sources and delete-source commands.

Sometimes one wants to share a single sandbox between multiple packages. This can be easily done with the --sandbox option:

$ mkdir -p /path/to/shared-sandbox
$ cd /path/to/shared-sandbox
$ cabal sandbox init --sandbox .
$ cd /path/to/package-a
$ cabal sandbox init --sandbox /path/to/shared-sandbox
$ cd /path/to/package-b
$ cabal sandbox init --sandbox /path/to/shared-sandbox

Note that cabal sandbox init --sandbox . puts all sandbox files into the current directory. By default, cabal sandbox init initialises a new sandbox in a newly-created subdirectory of the current working directory (./.cabal-sandbox).

Using multiple different compiler versions simultaneously is also supported, via the -w option:

$ cabal sandbox init
$ cabal install --only-dependencies -w /path/to/ghc-1 # Install dependencies for both compilers
$ cabal install --only-dependencies -w /path/to/ghc-2
$ cabal configure -w /path/to/ghc-1                   # Build with the first compiler
$ cabal build
$ cabal configure -w /path/to/ghc-2                   # Build with the second compiler
$ cabal build

It can be occasionally useful to run the compiler-specific package manager tool (e.g. ghc-pkg) tool on the sandbox package DB directly (for example, you may need to unregister some packages). The cabal sandbox hc-pkg command is a convenient wrapper that runs the compiler-specific package manager tool with the arguments:

$ cabal -v sandbox hc-pkg list
Using a sandbox located at /path/to/.cabal-sandbox
'ghc-pkg' '--global' '--no-user-package-conf'
    '--package-conf=/path/to/.cabal-sandbox/i386-linux-ghc-7.4.2-packages.conf.d'
    'list'
[...]

The --require-sandbox option makes all sandbox-aware commands (install/build/etc.) exit with error if there is no sandbox present. This makes it harder to accidentally modify the user package database. The option can be also turned on via the per-user configuration file (~/.cabal/config) or the per-project one ($PROJECT_DIR/cabal.config). The error can be squelched with --no-require-sandbox.

The option --sandbox-config-file allows to specify the location of the cabal.sandbox.config file (by default, cabal searches for it in the current directory). This provides the same functionality as shared sandboxes, but sometimes can be more convenient. Example:

$ mkdir my/sandbox
$ cd my/sandbox
$ cabal sandbox init
$ cd /path/to/my/project
$ cabal --sandbox-config-file=/path/to/my/sandbox/cabal.sandbox.config install
# Uses the sandbox located at /path/to/my/sandbox/.cabal-sandbox
$ cd ~
$ cabal --sandbox-config-file=/path/to/my/sandbox/cabal.sandbox.config install
# Still uses the same sandbox

The sandbox config file can be also specified via the CABAL_SANDBOX_CONFIG environment variable.

Finally, the flag --ignore-sandbox lets you temporarily ignore an existing sandbox:

$ mkdir my/sandbox
$ cd my/sandbox
$ cabal sandbox init
$ cabal --ignore-sandbox install text
# Installs 'text' in the user package database ('~/.cabal').

2.2.5. Creating a binary package¶

When creating binary packages (e.g. for Red Hat or Debian) one needs to create a tarball that can be sent to another system for unpacking in the root directory:

$ runhaskell Setup.hs configure --prefix=/usr
$ runhaskell Setup.hs build
$ runhaskell Setup.hs copy --destdir=/tmp/mypkg
$ tar -czf mypkg.tar.gz /tmp/mypkg/

If the package contains a library, you need two additional steps:

$ runhaskell Setup.hs register --gen-script
$ runhaskell Setup.hs unregister --gen-script

This creates shell scripts register.sh and unregister.sh, which must also be sent to the target system. After unpacking there, the package must be registered by running the register.sh script. The unregister.sh script would be used in the uninstall procedure of the package. Similar steps may be used for creating binary packages for Windows.

The following options are understood by all commands:

--help, -h or -?¶: List the available options for the command.

--verbose=n or -v n¶

Set the verbosity level (0-3). The normal level is 1; a missing n defaults to 2.

There is also an extended version of this command which can be used to fine-tune the verbosity of output. It takes the form [silent|normal|verbose|debug]flags, where flags is a list of + flags which toggle various aspects of output. At the moment, only +callsite and +callstack are supported, which respectively toggle call site and call stack printing (these are only supported if Cabal is built with a sufficiently recent GHC.)

The various commands and the additional options they support are described below. In the simple build infrastructure, any other options will be reported as errors.

2.2.6. setup configure¶

Prepare to build the package. Typically, this step checks that the target platform is capable of building the package, and discovers platform-specific features that are needed during the build.

The user may also adjust the behaviour of later stages using the options listed in the following subsections. In the simple build infrastructure, the values supplied via these options are recorded in a private file read by later stages.

If a user-supplied configure script is run (see the section on system-dependent parameters or on complex packages), it is passed the --with-hc-pkg, --prefix, --bindir, --libdir, --dynlibdir, --datadir, --libexecdir and --sysconfdir options. In addition the value of the --with-compiler option is passed in a --with-hc-pkg option and all options specified with --configure-option are passed on.

In Cabal 2.0, support for a single positional argument was added to setup configure This makes Cabal configure a the specific component to be configured. Specified names can be qualified with lib: or exe: in case just a name is ambiguous (as would be the case for a package named p which has a library and an executable named p.) This has the following effects:

Subsequent invocations of cabal build, register, etc. operate only on the configured component.
Cabal requires all “internal” dependencies (e.g., an executable depending on a library defined in the same package) must be found in the set of databases via --package-db (and related flags): these dependencies are assumed to be up-to-date. A dependency can be explicitly specified using --dependency simply by giving the name of the internal library; e.g., the dependency for an internal library named foo is given as --dependency=pkg-internal=pkg-1.0-internal-abcd.
Only the dependencies needed for the requested component are required. Similarly, when --exact-configuration is specified, it’s only necessary to specify --dependency for the component. (As mentioned previously, you must specify internal dependencies as well.)
Internal build-tool-depends and build-tools dependencies are expected to be in the PATH upon subsequent invocations of setup.

Full details can be found in the Componentized Cabal proposal.

2.2.6.1. Programs used for building¶

The following options govern the programs used to process the source files of a package:

--ghc or -g, --jhc, --lhc, --uhc¶: Specify which Haskell implementation to use to build the package. At most one of these flags may be given. If none is given, the implementation under which the setup script was compiled or interpreted is used.

--with-compiler=path or -w *path*¶

Specify the path to a particular compiler. If given, this must match the implementation selected above. The default is to search for the usual name of the selected implementation.

This flag also sets the default value of the --with-hc-pkg option to the package tool for this compiler. Check the output of setup configure -v to ensure that it finds the right package tool (or use --with-hc-pkg explicitly).

--with-hc-pkg=path¶: Specify the path to the package tool, e.g. ghc-pkg. The package tool must be compatible with the compiler specified by --with-compiler. If this option is omitted, the default value is determined from the compiler selected.

--with-prog=path¶: Specify the path to the program prog. Any program known to Cabal can be used in place of prog. It can either be a fully path or the name of a program that can be found on the program search path. For example: --with-ghc=ghc-6.6.1 or --with-cpphs=/usr/local/bin/cpphs. The full list of accepted programs is not enumerated in this user guide. Rather, run cabal install --help to view the list.

--prog-options=options¶: Specify additional options to the program prog. Any program known to Cabal can be used in place of prog. For example: --alex-options="--template=mytemplatedir/". The options is split into program options based on spaces. Any options containing embedded spaced need to be quoted, for example --foo-options='--bar="C:\Program File\Bar"'. As an alternative that takes only one option at a time but avoids the need to quote, use --prog-option instead.

--prog-option=option¶: Specify a single additional option to the program prog. For passing an option that contain embedded spaces, such as a file name with embedded spaces, using this rather than --prog-options means you do not need an additional level of quoting. Of course if you are using a command shell you may still need to quote, for example --foo-options="--bar=C:\Program File\Bar".

All of the options passed with either --prog-options or --prog-option are passed in the order they were specified on the configure command line.

2.2.6.2. Installation paths¶

The following options govern the location of installed files from a package:

--prefix=dir¶

The root of the installation. For example for a global install you might use /usr/local on a Unix system, or C:\Program Files on a Windows system. The other installation paths are usually subdirectories of prefix, but they don’t have to be.

In the simple build system, dir may contain the following path variables: $pkgid, $pkg, $version, $compiler, $os, $arch, $abi, $abitag

--bindir=dir¶

Executables that the user might invoke are installed here.

In the simple build system, dir may contain the following path variables: $prefix, $pkgid, $pkg, $version, $compiler, $os, $arch, $abi, $abitag

--libdir=dir¶

Object-code libraries are installed here.

In the simple build system, dir may contain the following path variables: $prefix, $bindir, $pkgid, $pkg, $version, $compiler, $os, $arch, $abi, $abitag

--dynlibdir=dir¶

Dynamic libraries are installed here.

By default, this is set to $libdir/$abi, which is usually not equal to $libdir/$libsubdir.

In the simple build system, dir may contain the following path variables: $prefix, $bindir, $libdir, $pkgid, $pkg, $version, $compiler, $os, $arch, $abi, $abitag

--libexecdir=dir¶

Executables that are not expected to be invoked directly by the user are installed here.

In the simple build system, dir may contain the following path variables: $prefix, $bindir, $libdir, $libsubdir, $pkgid, $pkg, $version, $compiler, $os, $arch, $abi, $abitag

--datadir=dir¶

Architecture-independent data files are installed here.

In the simple build system, dir may contain the following path variables: $prefix, $bindir, $libdir, $libsubdir, $pkgid, $pkg, $version, $compiler, $os, $arch, $abi, $abitag

--sysconfdir=dir¶

Installation directory for the configuration files.

In the simple build system, dir may contain the following path variables: $prefix, $bindir, $libdir, $libsubdir, $pkgid, $pkg, $version, $compiler, $os, $arch, $abi, $abitag

In addition the simple build system supports the following installation path options:

--libsubdir=dir¶

A subdirectory of libdir in which libraries are actually installed. For example, in the simple build system on Unix, the default libdir is /usr/local/lib, and libsubdir contains the compiler ABI and package identifier, e.g. x86_64-linux-ghc-8.0.2/mypkg-0.1.0-IxQNmCA7qrSEQNkoHSF7A, so libraries would be installed in /usr/local/lib/x86_64-linux-ghc-8.0.2/mypkg-0.1.0-IxQNmCA7qrSEQNkoHSF7A/.

dir may contain the following path variables: $pkgid, $pkg, $version, $compiler, $os, $arch, $abi, $abitag

--libexecsubdir=dir¶

A subdirectory of libexecdir in which private executables are installed. For example, in the simple build system on Unix, the default libexecdir is /usr/local/libexec, and libsubdir is x86_64-linux-ghc-8.0.2/mypkg-0.1.0, so private executables would be installed in /usr/local/libexec/x86_64-linux-ghc-8.0.2/mypkg-0.1.0/

dir may contain the following path variables: $pkgid, $pkg, $version, $compiler, $os, $arch, $abi, $abitag

--datasubdir=dir¶

A subdirectory of datadir in which data files are actually installed.

dir may contain the following path variables: $pkgid, $pkg, $version, $compiler, $os, $arch, $abi, $abitag

--docdir=dir¶

Documentation files are installed relative to this directory.

dir may contain the following path variables: $prefix, $bindir, $libdir, $libsubdir, $datadir, $datasubdir, $pkgid, $pkg, $version, $compiler, $os, $arch, $abi, $abitag

--htmldir=dir¶

HTML documentation files are installed relative to this directory.

dir may contain the following path variables: $prefix, $bindir, $libdir, $libsubdir, $datadir, $datasubdir, $docdir, $pkgid, $pkg, $version, $compiler, $os, $arch, $abi, $abitag

--program-prefix=prefix¶

Prepend prefix to installed program names.

prefix may contain the following path variables: $pkgid, $pkg, $version, $compiler, $os, $arch, $abi, $abitag

--program-suffix=suffix¶

Append suffix to installed program names. The most obvious use for this is to append the program’s version number to make it possible to install several versions of a program at once: --program-suffix='$version'.

suffix may contain the following path variables: $pkgid, $pkg, $version, $compiler, $os, $arch, $abi, $abitag

2.2.6.2.1. Path variables in the simple build system¶

For the simple build system, there are a number of variables that can be used when specifying installation paths. The defaults are also specified in terms of these variables. A number of the variables are actually for other paths, like $prefix. This allows paths to be specified relative to each other rather than as absolute paths, which is important for building relocatable packages (see prefix independence).

$prefix: The path variable that stands for the root of the installation. For an installation to be relocatable, all other installation paths must be relative to the $prefix variable.
$bindir: The path variable that expands to the path given by the --bindir configure option (or the default).
$libdir: As above but for --libdir
$libsubdir: As above but for --libsubdir
$dynlibdir: As above but for --dynlibdir
$datadir: As above but for --datadir
$datasubdir: As above but for --datasubdir
$docdir: As above but for --docdir
$pkgid: The name and version of the package, e.g. mypkg-0.2
$pkg: The name of the package, e.g. mypkg
$version: The version of the package, e.g. 0.2
$compiler: The compiler being used to build the package, e.g. ghc-6.6.1
$os: The operating system of the computer being used to build the package, e.g. linux, windows, osx, freebsd or solaris
$arch: The architecture of the computer being used to build the package, e.g. i386, x86_64, ppc or sparc
$abitag: An optional tag that a compiler can use for telling incompatible ABI’s on the same architecture apart. GHCJS encodes the underlying GHC version in the ABI tag.
$abi: A shortcut for getting a path that completely identifies the platform in terms of binary compatibility. Expands to the same value as $arch-$os-compiler-$abitag if the compiler uses an abi tag, $arch-$os-$compiler if it doesn’t.

2.2.6.2.2. Paths in the simple build system¶

For the simple build system, the following defaults apply:

Default installation paths¶
Option	Unix Default	Windows Default
`--prefix` (global)	`/usr/local`	`%PROGRAMFILES%\Haskell`
`--prefix` (per-user)	`$HOME/.cabal`	`%APPDATA%\cabal`
`--bindir`	`$prefix/bin`	`$prefix\bin`
`--libdir`	`$prefix/lib`	`$prefix`
`--libsubdir` (others)	`$pkgid/$compiler`	`$pkgid\$compiler`
`--dynlibdir`	`$libdir/$abi`	`$libdir\$abi`
`--libexecdir`	`$prefix/libexec`	`$prefix\$pkgid`
`--datadir` (executable)	`$prefix/share`	`$prefix`
`--datadir` (library)	`$prefix/share`	`%PROGRAMFILES%\Haskell`
`--datasubdir`	`$pkgid`	`$pkgid`
`--docdir`	`$datadir/doc/$pkgid`	`$prefix\doc\$pkgid`
`--sysconfdir`	`$prefix/etc`	`$prefix\etc`
`--htmldir`	`$docdir/html`	`$docdir\html`
`--program-prefix`	(empty)	(empty)
`--program-suffix`	(empty)	(empty)

2.2.6.2.3. Prefix-independence¶

On Windows it is possible to obtain the pathname of the running program. This means that we can construct an installable executable package that is independent of its absolute install location. The executable can find its auxiliary files by finding its own path and knowing the location of the other files relative to $bindir. Prefix-independence is particularly useful: it means the user can choose the install location (i.e. the value of $prefix) at install-time, rather than having to bake the path into the binary when it is built.

In order to achieve this, we require that for an executable on Windows, all of $bindir, $libdir, $dynlibdir, $datadir and $libexecdir begin with $prefix. If this is not the case then the compiled executable will have baked-in all absolute paths.

The application need do nothing special to achieve prefix-independence. If it finds any files using getDataFileName and the other functions provided for the purpose, the files will be accessed relative to the location of the current executable.

A library cannot (currently) be prefix-independent, because it will be linked into an executable whose file system location bears no relation to the library package.

2.2.6.3. Controlling Flag Assignments¶

Flag assignments (see the resolution of conditions and flags) can be controlled with the following command line options.

-f flagname or -f -flagname¶: Force the specified flag to true or false (if preceded with a -). Later specifications for the same flags will override earlier, i.e., specifying -fdebug -f-debug is equivalent to -f-debug

--flags=flagspecs¶: Same as -f, but allows specifying multiple flag assignments at once. The parameter is a space-separated list of flag names (to force a flag to true), optionally preceded by a - (to force a flag to false). For example, --flags="debug -feature1 feature2" is equivalent to -fdebug -f-feature1 -ffeature2.

2.2.6.4. Building Test Suites¶

--enable-tests¶: Build the test suites defined in the package description file during the build stage. Check for dependencies required by the test suites. If the package is configured with this option, it will be possible to run the test suites with the test command after the package is built.

--disable-tests¶: (default) Do not build any test suites during the build stage. Do not check for dependencies required only by the test suites. It will not be possible to invoke the test command without reconfiguring the package.

--enable-coverage¶: Build libraries and executables (including test suites) with Haskell Program Coverage enabled. Running the test suites will automatically generate coverage reports with HPC.

--disable-coverage¶: (default) Do not enable Haskell Program Coverage.

2.2.6.5. Miscellaneous options¶

--user¶: Does a per-user installation. This changes the default installation prefix. It also allow dependencies to be satisfied by the user’s package database, in addition to the global database. This also implies a default of --user for any subsequent install command, as packages registered in the global database should not depend on packages registered in a user’s database.

--global¶: (default) Does a global installation. In this case package dependencies must be satisfied by the global package database. All packages in the user’s package database will be ignored. Typically the final installation step will require administrative privileges.

--package-db=db¶

Allows package dependencies to be satisfied from this additional package database db in addition to the global package database. All packages in the user’s package database will be ignored. The interpretation of db is implementation-specific. Typically it will be a file or directory. Not all implementations support arbitrary package databases.

This pushes an extra db onto the db stack. The --global and --user mode switches add the respective [Global] and [Global, User] dbs to the initial stack. There is a compiler-implementation constraint that the global db must appear first in the stack, and if the user one appears at all, it must appear immediately after the global db.

To reset the stack, use --package-db=clear.

--ipid=ipid¶: Specifies the installed package identifier of the package to be built; this identifier is passed on to GHC and serves as the basis for linker symbols and the id field in a ghc-pkg registration. When a package has multiple components, the actual component identifiers are derived off of this identifier (e.g., an internal library foo from package p-0.1-abcd will get the identifier p-0.1-abcd-foo.

--cid=cid¶: Specifies the component identifier of the component being built; this is only valid if you are configuring a single component.

--default-user-config=file¶: Allows a “default” cabal.config freeze file to be passed in manually. This file will only be used if one does not exist in the project directory already. Typically, this can be set from the global cabal config file so as to provide a default set of partial constraints to be used by projects, providing a way for users to peg themselves to stable package collections.

--enable-optimization[=n] or -O [n]¶

(default) Build with optimization flags (if available). This is appropriate for production use, taking more time to build faster libraries and programs.

The optional n value is the optimisation level. Some compilers support multiple optimisation levels. The range is 0 to 2. Level 0 is equivalent to --disable-optimization, level 1 is the default if no n parameter is given. Level 2 is higher optimisation if the compiler supports it. Level 2 is likely to lead to longer compile times and bigger generated code.

When optimizations are enabled, Cabal passes -O2 to the C compiler.

--disable-optimization¶: Build without optimization. This is suited for development: building will be quicker, but the resulting library or programs will be slower.

--enable-profiling¶

Build libraries and executables with profiling enabled (for compilers that support profiling as a separate mode). For this to work, all libraries used by this package must also have been built with profiling support. For libraries this involves building an additional instance of the library in addition to the normal non-profiling instance. For executables it changes the single executable to be built in profiling mode.

This flag covers both libraries and executables, but can be overridden by the --enable-library-profiling flag.

See also the --profiling-detail flag below.

--disable-profiling¶: (default) Do not enable profiling in generated libraries and executables.

--enable-library-profiling or -p¶

As with --enable-profiling above, but it applies only for libraries. So this generates an additional profiling instance of the library in addition to the normal non-profiling instance.

The --enable-profiling flag controls the profiling mode for both libraries and executables, but if different modes are desired for libraries versus executables then use --enable-library-profiling as well.

--disable-library-profiling¶: (default) Do not generate an additional profiling version of the library.

--profiling-detail[=level]¶

Some compilers that support profiling, notably GHC, can allocate costs to different parts of the program and there are different levels of granularity or detail with which this can be done. In particular for GHC this concept is called “cost centers”, and GHC can automatically add cost centers, and can do so in different ways.

This flag covers both libraries and executables, but can be overridden by the --library-profiling-detail flag.

Currently this setting is ignored for compilers other than GHC. The levels that cabal currently supports are:

default: For GHC this uses exported-functions for libraries and toplevel-functions for executables.
none: No costs will be assigned to any code within this component.
exported-functions: Costs will be assigned at the granularity of all top level functions exported from each module. In GHC specifically, this is for non-inline functions.
toplevel-functions: Costs will be assigned at the granularity of all top level functions in each module, whether they are exported from the module or not. In GHC specifically, this is for non-inline functions.
all-functions: Costs will be assigned at the granularity of all functions in each module, whether top level or local. In GHC specifically, this is for non-inline toplevel or where-bound functions or values.

This flag is new in Cabal-1.24. Prior versions used the equivalent of none above.

--library-profiling-detail[=level]¶

As with --profiling-detail above, but it applies only for libraries.

The level for both libraries and executables is set by the --profiling-detail flag, but if different levels are desired for libraries versus executables then use --library-profiling-detail as well.

--enable-library-vanilla¶: (default) Build ordinary libraries (as opposed to profiling libraries). This is independent of the --enable-library-profiling option. If you enable both, you get both.

--disable-library-vanilla¶: Do not build ordinary libraries. This is useful in conjunction with --enable-library-profiling to build only profiling libraries, rather than profiling and ordinary libraries.

--enable-library-for-ghci¶: (default) Build libraries suitable for use with GHCi.

--disable-library-for-ghci¶: Not all platforms support GHCi and indeed on some platforms, trying to build GHCi libs fails. In such cases this flag can be used as a workaround.

--enable-split-objs¶: Use the GHC -split-objs feature when building the library. This reduces the final size of the executables that use the library by allowing them to link with only the bits that they use rather than the entire library. The downside is that building the library takes longer and uses considerably more memory.

--disable-split-objs¶: (default) Do not use the GHC -split-objs feature. This makes building the library quicker but the final executables that use the library will be larger.

--enable-executable-stripping¶

(default) When installing binary executable programs, run the strip program on the binary. This can considerably reduce the size of the executable binary file. It does this by removing debugging information and symbols. While such extra information is useful for debugging C programs with traditional debuggers it is rarely helpful for debugging binaries produced by Haskell compilers.

Not all Haskell implementations generate native binaries. For such implementations this option has no effect.

--disable-executable-stripping¶: Do not strip binary executables during installation. You might want to use this option if you need to debug a program using gdb, for example if you want to debug the C parts of a program containing both Haskell and C code. Another reason is if your are building a package for a system which has a policy of managing the stripping itself (such as some Linux distributions).

--enable-shared¶: Build shared library. This implies a separate compiler run to generate position independent code as required on most platforms.

--disable-shared¶: (default) Do not build shared library.

--enable-static¶: Build a static library. This passes -staticlib to GHC (available for iOS, and with 8.4 more platforms). The result is an archive .a containing all dependent haskell libararies combined.

--disable-static¶: (default) Do not build a static library.

--enable-executable-dynamic¶: Link executables dynamically. The executable’s library dependencies should be built as shared objects. This implies --enable-shared unless --disable-shared is explicitly specified.

--disable-executable-dynamic¶: (default) Link executables statically.

--configure-option=str¶: An extra option to an external configure script, if one is used (see the section on system-dependent parameters). There can be several of these options.

--extra-include-dirs[=dir]¶

An extra directory to search for C header files. You can use this flag multiple times to get a list of directories.

You might need to use this flag if you have standard system header files in a non-standard location that is not mentioned in the package’s .cabal file. Using this option has the same affect as appending the directory dir to the include-dirs field in each library and executable in the package’s .cabal file. The advantage of course is that you do not have to modify the package at all. These extra directories will be used while building the package and for libraries it is also saved in the package registration information and used when compiling modules that use the library.

--extra-lib-dirs[=dir]¶: An extra directory to search for system libraries files. You can use this flag multiple times to get a list of directories.

--extra-framework-dirs[=dir]¶

An extra directory to search for frameworks (OS X only). You can use this flag multiple times to get a list of directories.

You might need to use this flag if you have standard system libraries in a non-standard location that is not mentioned in the package’s .cabal file. Using this option has the same affect as appending the directory dir to the extra-lib-dirs field in each library and executable in the package’s .cabal file. The advantage of course is that you do not have to modify the package at all. These extra directories will be used while building the package and for libraries it is also saved in the package registration information and used when compiling modules that use the library.

--dependency[=pkgname=ipid]¶: Specify that a particular dependency should used for a particular package name. In particular, it declares that any reference to pkgname in a build-depends should be resolved to ipid.

--exact-configuration¶: This changes Cabal to require every dependency be explicitly specified using --dependency, rather than use Cabal’s (very simple) dependency solver. This is useful for programmatic use of Cabal’s API, where you want to error if you didn’t specify enough --dependency flags.

--allow-newer[=pkgs], --allow-older[=pkgs]¶

Selectively relax upper or lower bounds in dependencies without editing the package description respectively.

The following description focuses on upper bounds and the --allow-newer flag, but applies analogously to --allow-older and lower bounds. --allow-newer and --allow-older can be used at the same time.

If you want to install a package A that depends on B >= 1.0 && < 2.0, but you have the version 2.0 of B installed, you can compile A against B 2.0 by using cabal install --allow-newer=B A. This works for the whole package index: if A also depends on C that in turn depends on B < 2.0, C’s dependency on B will be also relaxed.

Example:

$ cd foo
$ cabal configure
Resolving dependencies...
cabal: Could not resolve dependencies:
[...]
$ cabal configure --allow-newer
Resolving dependencies...
Configuring foo...

Additional examples:

# Relax upper bounds in all dependencies.
$ cabal install --allow-newer foo

# Relax upper bounds only in dependencies on bar, baz and quux.
$ cabal install --allow-newer=bar,baz,quux foo

# Relax the upper bound on bar and force bar==2.1.
$ cabal install --allow-newer=bar --constraint="bar==2.1" foo

It’s also possible to limit the scope of --allow-newer to single packages with the --allow-newer=scope:dep syntax. This means that the dependency on dep will be relaxed only for the package scope.

Example:

# Relax upper bound in foo's dependency on base; also relax upper bound in
# every package's dependency on lens.
$ cabal install --allow-newer=foo:base,lens

# Relax upper bounds in foo's dependency on base and bar's dependency
# on time; also relax the upper bound in the dependency on lens specified by
# any package.
$ cabal install --allow-newer=foo:base,lens --allow-newer=bar:time

Finally, one can enable --allow-newer permanently by setting allow-newer: True in the ~/.cabal/config file. Enabling ‘allow-newer’ selectively is also supported in the config file (allow-newer: foo, bar, baz:base).

--constraint=constraint¶

Restrict solutions involving a package to given version bounds, flag settings, and other properties. For example, to consider only install plans that use version 2.1 of bar or do not use bar at all, write:

$ cabal install --constraint="bar == 2.1"

Version bounds have the same syntax as build-depends. As a special case, the following prevents bar from being used at all:

# Note: this is just syntax sugar for '> 1 && < 1', and is
# supported by build-depends.
$ cabal install --constraint="bar -none"

You can also specify flag assignments:

# Require bar to be installed with the foo flag turned on and
# the baz flag turned off.
$ cabal install --constraint="bar +foo -baz"

To specify multiple constraints, you may pass the constraint option multiple times.

There are also some more specialized constraints, which most people don’t generally need:

# Require that a version of bar be used that is already installed in
# the global package database.
$ cabal install --constraint="bar installed"

# Require the local source copy of bar to be used.
# (Note: By default, if we have a local package we will
# automatically use it, so it will generally not be necessary to
# specify this.)
$ cabal install --constraint="bar source"

# Require that bar have test suites and benchmarks enabled.
$ cabal install --constraint="bar test" --constraint="bar bench"

By default, constraints only apply to build dependencies (build-depends), build dependencies of build dependencies, and so on. Constraints normally do not apply to dependencies of the Setup.hs script of any package (setup-depends) nor do they apply to build tools (build-tool-depends) or the dependencies of build tools. To explicitly apply a constraint to a setup or build tool dependency, you can add a qualifier to the constraint as follows:

# Example use of the 'any' qualifier. This constraint
# applies to package bar anywhere in the dependency graph.
$ cabal install --constraint="any.bar == 1.0"

# Example uses of 'setup' qualifiers.

# This constraint applies to package bar when it is a
# dependency of any Setup.hs script.
$ cabal install --constraint="setup.bar == 1.0"

# This constraint applies to package bar when it is a
# dependency of the Setup.hs script of package foo.
$ cabal install --constraint="foo:setup.bar == 1.0"

--preference=preference¶: Specify a soft constraint on versions of a package. The solver will attempt to satisfy these preferences on a “best-effort” basis.

--disable-response-files¶: Enable workaround for older versions of programs such as ar or ld that do not support response file arguments (i.e. @file arguments). You may want this flag only if you specify custom ar executable. For system ar or the one bundled with ghc on Windows the cabal should do the right thing and hence should normally not require this flag.

2.2.7. setup build¶

Perform any preprocessing or compilation needed to make this package ready for installation.

This command takes the following options:

--prog-options=options, --prog-option=option¶: These are mostly the same as the options configure step. Unlike the options specified at the configure step, any program options specified at the build step are not persistent but are used for that invocation only. They options specified at the build step are in addition not in replacement of any options specified at the configure step.

2.2.8. setup haddock¶

Build the documentation for the package using Haddock. By default, only the documentation for the exposed modules is generated (but see the --executables and --internal flags below).

This command takes the following options:

--hoogle¶: Generate a file dist/doc/html/pkgid.txt, which can be converted by Hoogle into a database for searching. This is equivalent to running Haddock with the --hoogle flag.

--html-location=url¶

Specify a template for the location of HTML documentation for prerequisite packages. The substitutions (see listing) are applied to the template to obtain a location for each package, which will be used by hyperlinks in the generated documentation. For example, the following command generates links pointing at Hackage pages:

setup haddock –html-location=’http://hackage.haskell.org/packages/archive/$pkg/latest/doc/html’

Here the argument is quoted to prevent substitution by the shell. If this option is omitted, the location for each package is obtained using the package tool (e.g. ghc-pkg).

--executables¶: Also run Haddock for the modules of all the executable programs. By default Haddock is run only on the exported modules.

--internal¶: Run Haddock for the all modules, including unexposed ones, and make Haddock generate documentation for unexported symbols as well.

--css=path¶: The argument path denotes a CSS file, which is passed to Haddock and used to set the style of the generated documentation. This is only needed to override the default style that Haddock uses.

--hyperlink-source¶: Generate Haddock documentation integrated with HsColour . First, HsColour is run to generate colourised code. Then Haddock is run to generate HTML documentation. Each entity shown in the documentation is linked to its definition in the colourised code.

--hscolour-css=path¶: The argument path denotes a CSS file, which is passed to HsColour as in

runhaskell Setup.hs hscolour –css=*path*

2.2.9. setup hscolour¶

Produce colourised code in HTML format using HsColour. Colourised code for exported modules is put in dist/doc/html/pkgid/src.

This command takes the following options:

--executables¶: Also run HsColour on the sources of all executable programs. Colourised code is put in dist/doc/html/pkgid/executable/src.

--css=path¶: Use the given CSS file for the generated HTML files. The CSS file defines the colours used to colourise code. Note that this copies the given CSS file to the directory with the generated HTML files (renamed to hscolour.css) rather than linking to it.

2.2.10. setup install¶

Copy the files into the install locations and (for library packages) register the package with the compiler, i.e. make the modules it contains available to programs.

The install locations are determined by options to setup configure.

This command takes the following options:

--global¶: Register this package in the system-wide database. (This is the default, unless the setup configure --user option was supplied to the configure command.)

--user¶: Register this package in the user’s local package database. (This is the default if the setup configure --user option was supplied to the configure command.)

2.2.11. setup copy¶

Copy the files without registering them. This command is mainly of use to those creating binary packages.

This command takes the following option:

--destdir=path¶: Specify the directory under which to place installed files. If this is not given, then the root directory is assumed.

2.2.12. setup register¶

Register this package with the compiler, i.e. make the modules it contains available to programs. This only makes sense for library packages. Note that the install command incorporates this action. The main use of this separate command is in the post-installation step for a binary package.

This command takes the following options:

--global¶: Register this package in the system-wide database. (This is the default.)

--user¶: Register this package in the user’s local package database.

--gen-script¶: Instead of registering the package, generate a script containing commands to perform the registration. On Unix, this file is called register.sh, on Windows, register.bat. This script might be included in a binary bundle, to be run after the bundle is unpacked on the target system.

--gen-pkg-config[=path]¶

Instead of registering the package, generate a package registration file (or directory, in some circumstances). This only applies to compilers that support package registration files which at the moment is only GHC. The file should be used with the compiler’s mechanism for registering packages. This option is mainly intended for packaging systems. If possible use the --gen-script option instead since it is more portable across Haskell implementations. The path is optional and can be used to specify a particular output file to generate. Otherwise, by default the file is the package name and version with a .conf extension.

This option outputs a directory if the package requires multiple registrations: this can occur if internal/convenience libraries are used. These configuration file names are sorted so that they can be registered in order.

--inplace¶

Registers the package for use directly from the build tree, without needing to install it. This can be useful for testing: there’s no need to install the package after modifying it, just recompile and test.

This flag does not create a build-tree-local package database. It still registers the package in one of the user or global databases.

However, there are some caveats. It only works with GHC (currently). It only works if your package doesn’t depend on having any supplemental files installed — plain Haskell libraries should be fine.

2.2.13. setup unregister¶

Deregister this package with the compiler.

This command takes the following options:

--global¶: Deregister this package in the system-wide database. (This is the default.)

--user¶: Deregister this package in the user’s local package database.

--gen-script¶: Instead of deregistering the package, generate a script containing commands to perform the deregistration. On Unix, this file is called unregister.sh, on Windows, unregister.bat. This script might be included in a binary bundle, to be run on the target system.

2.2.14. setup clean¶

Remove any local files created during the configure, build, haddock, register or unregister steps, and also any files and directories listed in the extra-tmp-files field.

This command takes the following options:

--save-configure, -s¶: Keeps the configuration information so it is not necessary to run the configure step again before building.

2.2.15. setup test¶

Run the test suites specified in the package description file. Aside from the following flags, Cabal accepts the name of one or more test suites on the command line after test. When supplied, Cabal will run only the named test suites, otherwise, Cabal will run all test suites in the package.

--builddir=dir¶: The directory where Cabal puts generated build files (default: dist). Test logs will be located in the test subdirectory.

--human-log=path¶: The template used to name human-readable test logs; the path is relative to dist/test. By default, logs are named according to the template $pkgid-$test-suite.log, so that each test suite will be logged to its own human-readable log file. Template variables allowed are: $pkgid, $compiler, $os, $arch, $abi, $abitag, $test-suite, and $result.

--machine-log=path¶: The path to the machine-readable log, relative to dist/test. The default template is $pkgid.log. Template variables allowed are: $pkgid, $compiler, $os, $arch, $abi, $abitag and $result.

--show-details=filter¶: Determines if the results of individual test cases are shown on the terminal. May be always (always show), never (never show), failures (show only failed results), or streaming (show all results in real time).

--test-options=options¶
Give extra options to the test executables.¶

--test-option=option¶: give an extra option to the test executables. There is no need to quote options containing spaces because a single option is assumed, so options will not be split on spaces.

2.2.16. setup sdist¶

Create a system- and compiler-independent source distribution in a file package-version.tar.gz in the dist subdirectory, for distribution to package builders. When unpacked, the commands listed in this section will be available.

The files placed in this distribution are the package description file, the setup script, the sources of the modules named in the package description file, and files named in the license-file, main-is, c-sources, asm-sources, cmm-sources, js-sources, data-files, extra-source-files and extra-doc-files fields.

This command takes the following option:

--snapshot¶: Append today’s date (in “YYYYMMDD” format) to the version number for the generated source package. The original package is unaffected.