7. cabal.project Reference

cabal.project files support a variety of options which configure the details of your build. The general syntax of a cabal.project file is similar to that of a Cabal file: there are a number of fields, some of which live inside stanzas (groups of fields that apply to only part of a project or can be referenced as a unit):

packages: */*.cabal
with-compiler: /opt/ghc/8.0.1/bin/ghc

package cryptohash
  optimization: False

In general, the accepted field names coincide with the accepted command line flags that cabal install and other commands take. For example, cabal configure --enable-profiling will write out a project file with profiling: True.

The full configuration of a project is determined by combining the following sources (later entries override earlier ones, except for appendable options):

The user-wide global configuration (default: ~/.config/cabal/config)
cabal.project (the project configuration)
cabal.project.freeze (the output of cabal freeze)
cabal.project.local (the output of cabal configure)

Any call to cabal build will consider cabal.project* files from parent directories when there is none in the current directory.

7.1. Conditionals and imports

As of cabal-install version 3.8, cabal supports conditional logic and imports in cabal.project files. Conditions in cabal may case on operating system, architecture, and compiler (i.e. there is no support for a notion of custom flags in project files). Imports may specify local filepaths or remote urls, and may reference either cabal.project files or v1-style cabal.config freeze files. As a usage example:

if(os(darwin))
  optimization: False
elif(os(freebsd))
  packages: freebsd/*.cabal
else
  optimization: True

import: https://some.remote.source/subdir/cabal.config

import: relativepath/extra-project.project

import: /absolutepath/some-project.project

Using conditionals will force cabal to find a ghc to derive architecture and version information from, which will force some commands (update, sdist) to require ghc present where otherwise it would not be necessitated.

7.2. Specifying the local packages

The following top-level options specify what the local packages of a project are:

packages: package location list (space or comma separated)

Default value:: ./*.cabal

Warning

The default value ./*.cabal only takes effect if there is no explicit cabal.project file. If you use such explicit file you must fill the field.

Specifies the list of package locations which contain the local packages to be built by this project. Package locations can take the following forms:

They can specify a Cabal file, or a directory containing a Cabal file, e.g., packages: Cabal cabal-install/cabal-install.cabal.
They can specify glob-style wildcards, which must match one or more (a) directories containing a (single) Cabal file, (b) Cabal files (extension .cabal), or (c) tarballs which contain Cabal packages (extension .tar.gz). For example, to match all Cabal files in all subdirectories, as well as the Cabal projects in the parent directories foo and bar, use packages: */*.cabal ../{foo,bar}/
They can specify an http, https or file URL, representing the path to a remote tarball to be downloaded and built.

There is no command line variant of this field; see issue #3585. Note that the default value is only included if there is no cabal.project file. The field is appendable which means there would be no way to drop the default value if it was included.

optional-packages: package location list (space or comma-separated)

Default value:: empty

Like packages, specifies a list of package locations containing local packages to be built. Unlike packages, if we glob for a package, it is permissible for the glob to match against zero packages. The intended use-case for optional-packages is to make it so that vendored packages can be automatically picked up if they are placed in a subdirectory, but not error if there aren’t any.

There is no command line variant of this field.

extra-packages: package list with version bounds (comma separated)

Specifies a list of external packages from Hackage, which should be considered local packages. The motivation for extra-packages is making libraries that are not dependencies of any package in the project available for use in ghci.

There is no command line variant of this field.

All local packages are vendored, in the sense that if other packages (including external ones from Hackage) depend on a package with the name of a local package, the local package is preferentially used. For subdirectories to be considered local packages, the following setting can be used:

packages: ./*.cabal
optional-packages: ./*/*.cabal

…then any package can be vendored simply by making a checkout in the top-level project directory, as might be seen in this hypothetical directory layout:

foo.cabal
foo-helper/     # local package
unix/           # vendored external package

All of these options support globs. cabal build has its own glob format:

Anywhere in a path, as many times as you like, you can specify an asterisk * wildcard. E.g., */*.cabal matches all .cabal files in all immediate subdirectories. Like in glob(7), asterisks do not match hidden files unless there is an explicit period, e.g., .*/foo.cabal will match .private/foo.cabal (but */foo.cabal will not).
You can use braces to specify specific directories; e.g., {vendor,pkgs}/*.cabal matches all Cabal files in the vendor and pkgs subdirectories.

Formally, the format is described by the following BNF:

Todo

convert globbing grammar to proper ABNF syntax

FilePathGlob    ::= FilePathRoot FilePathGlobRel
FilePathRoot    ::= {- empty -}        # relative to cabal.project
                  | "/"                # Unix root
                  | [a-zA-Z] ":" [/\\] # Windows root
                  | "~"                # home directory
FilePathGlobRel ::= Glob "/"  FilePathGlobRel # Unix directory
                  | Glob "\\" FilePathGlobRel # Windows directory
                  | Glob         # file
                  | {- empty -}  # trailing slash
Glob      ::= GlobPiece *
GlobPiece ::= "*"            # wildcard
            | [^*{},/\\] *   # literal string
            | "\\" [*{},]    # escaped reserved character
            | "{" Glob "," ... "," Glob "}" # union (match any of these)

7.2.1. Specifying Packages from Remote Version Control Locations

Starting with Cabal 2.4, there is now a stanza source-repository-package for specifying packages from an external version control.

packages: .

source-repository-package
    type: git
    location: https://github.com/hvr/HsYAML.git
    tag: e70cf0c171c9a586b62b3f75d72f1591e4e6aaa1

source-repository-package
    type: git
    location: https://github.com/well-typed/cborg
    tag: 3d274c14ca3077c3a081ba7ad57c5182da65c8c1
    subdir: cborg

source-repository-package
    type: git
    location: https://github.com/haskell/network.git
    tag: e76fdc753e660dfa615af6c8b6a2ad9ddf6afe70
    post-checkout-command: autoreconf -i

cabal-install 3.4 sdists the source-repository-package repositories and uses resulting tarballs as project packages. This allows sharing of packages across different projects.

type: VCS kind

location: VCS location (usually URL)

tag: VCS tag

subdir: subdirectory list: Use one or more subdirectories of the repository.

post-checkout-command: command: Run command in the checked out repository, prior sdisting.

7.3. Global configuration options

The following top-level configuration options are not specific to any package, and thus apply globally:

verbose: nat

--verbose=n, -vn 

Default value:: 1

Control the verbosity of cabal commands, valid values are from 0 to 3.

The command line variant of this field is --verbose=2; a short form -v2 is also supported.

jobs: nat or $ncpus

--jobs=n, -jn , --jobs=$ncpus

Default value:: 1

Run nat jobs simultaneously when building. If $ncpus is specified, run the number of jobs equal to the number of CPUs. Package building is often quite parallel, so turning on parallelism can speed up build times quite a bit!

The command line variant of this field is --jobs=2; a short form -j2 is also supported; a bare --jobs or -j is equivalent to --jobs=$ncpus.

keep-going: boolean

--keep-going 

Default value:: False

If true, after a build failure, continue to build other unaffected packages.

The command line variant of this field is --keep-going.

--builddir=DIR

Specifies the name of the directory where build products for build will be stored; defaults to dist-newstyle. If a relative name is specified, this directory is resolved relative to the root of the project (i.e., where the cabal.project file lives.)

This option cannot be specified via a cabal.project file.

--project-file=FILE

Specifies the name of the project file used to specify the rest of the top-level configuration; defaults to cabal.project. This name not only specifies the name of the main project file, but also the auxiliary project files cabal.project.freeze and cabal.project.local; for example, if you specify --project-file=my.project, then the other files that will be probed are my.project.freeze and my.project.local.

If the specified project file is a relative path, we will look for the file relative to the current working directory, and then for the parent directory, until the project file is found or we have hit the top of the user’s home directory.

This option cannot be specified via a cabal.project file.

--ignore-project: Ignores the local cabal.project file and uses the default configuration with the local foo.cabal file. Note that if this flag is set while the --project-file flag is also set then this flag will be ignored.

--store-dir=DIR: Specifies the name of the directory of the global package store.

package-dbs: package DB stack (comma separated)

--package-db=[clear, global , user , PATH] 

Since:: Cabal 3.7

There are three package databases involved with most builds:

global: Compiler installation of rts, base, etc.
store: Nix-style local build cache
in-place: Project-specific build directory

By default, the package stack you will have with v2 commands is:

-- [global, store]

So all remote packages required by your project will be registered in the store package db (because it is last).

When cabal starts building your local projects, it appends the in-place db to the end:

-- [global, store, in-place]

So your local packages get put in dist-newstyle instead of the store.

This flag manipulates the default prefix: [global, store] and accepts paths, the special value global referring to the global package db, and clear which removes all prior entries. For example,

-- [global, store, foo]
package-dbs: foo

-- [foo]
package-dbs: clear, foo

-- [bar, baz]
package-dbs: clear, foo, clear, bar, baz

The command line variant of this flag is --package-db=DB which can be specified multiple times.

7.4. Phase control

The following settings apply to commands that result in build actions (build, run, repl, test…), and control which phases of the build are executed.

--dry-run: Do not download, build, or install anything, only print what would happen.

--only-configure: Instead of performing a full build just run the configure step. Only accepted by the build command.

--only-download: Do not build anything, only fetch the packages.

--only-dependencies: Install only the dependencies necessary to build the given packages. Not accepted by the repl command.

7.5. Solver configuration options

The following settings control the behavior of the dependency solver:

constraints: constraints list (comma separated)

--constraint="pkg > 2.0", -c "pkg >= 2.0"

Add extra constraints to the version bounds, flag settings, and other properties a solver can pick for a package. For example:

constraints: bar == 2.1

A package can be specified multiple times in constraints, in which case the specified constraints are intersected. This is useful, since the syntax does not allow you to specify multiple constraints at once. For example, to specify both version bounds and flag assignments, you would write:

constraints: bar == 2.1,
             bar +foo -baz

Valid constraints take the same form as for the runhaskell Setup.hs configure --constraint command line option.

preferences: preference (comma separated)

--preference="pkg > 2.0"

Like constraints, but the solver will attempt to satisfy these preferences on a best-effort basis. The resulting install is locally optimal with respect to preferences; specifically, no single package could be replaced with a more preferred version that still satisfies the hard constraints.

Operationally, preferences can cause the solver to attempt certain version choices of a package before others, which can improve dependency solver runtime.

One way to use preferences is to take a known working set of constraints (e.g., via cabal freeze) and record them as preferences. In this case, the solver will first attempt to use this configuration, and if this violates hard constraints, it will try to find the minimal number of upgrades to satisfy the hard constraints again.

The command line variant of this field is --preference="pkg >= 2.0"; to specify multiple preferences, pass the flag multiple times.

allow-newer: none, all or list of scoped package names (space or comma separated)

--allow-newer , --allow-newer=[none, all , [scope:][^]pkg] 

Default value:: none

Allow the solver to pick more recent version of some packages than would normally be permitted by the build-depends bounds of packages in the install plan. This option may be useful if the dependency solver cannot otherwise find a valid install plan.

For example, to relax pkgs build-depends upper bound on dep-pkg, write a scoped package name of the form:

allow-newer: pkg:dep-pkg

If the scope shall be limited to specific releases of pkg, the extended form as in

allow-newer: pkg-1.2.3:dep-pkg, pkg-1.1.2:dep-pkg

can be used to limit the relaxation of dependencies on dep-pkg by the pkg-1.2.3 and pkg-1.1.2 releases only.

The scoped syntax is recommended, as it is often only a single package whose upper bound is misbehaving. In this case, the upper bounds of other packages should still be respected; indeed, relaxing the bound can break some packages which test the selected version of packages.

The syntax also allows to prefix the dependee package with a modifier symbol to modify the scope/semantic of the relaxation transformation in a additional ways. Currently only one modifier symbol is defined, i.e. ^ (i.e. caret) which causes the relaxation to be applied only to ^>= operators and leave all other version operators untouched.

However, in some situations (e.g., when attempting to build packages on a new version of GHC), it is useful to disregard all upper-bounds, with respect to a package or all packages. This can be done by specifying just a package name, or using the keyword all to specify all packages:

-- Disregard upper bounds involving the dependencies on
-- packages bar, baz. For quux only, relax
-- 'quux ^>= ...'-style constraints only.
allow-newer: bar, baz, ^quux

-- Disregard all upper bounds when dependency solving
allow-newer: all

-- Disregard all `^>=`-style upper bounds when dependency solving
allow-newer: ^all

For consistency, there is also the explicit wildcard scope syntax * (or its alphabetic synonym all). Consequently, the examples above are equivalent to the explicitly scoped variants:

allow-newer: all:bar, *:baz, *:^quux

allow-newer: *:*
allow-newer: all:all

allow-newer: *:^*
allow-newer: all:^all

In order to ignore all bounds specified by a package pkg-1.2.3 you can combine scoping with a right-hand-side wildcard like so

-- Disregard any upper bounds specified by pkg-1.2.3
allow-newer: pkg-1.2.3:*

-- Disregard only `^>=`-style upper bounds in pkg-1.2.3
allow-newer: pkg-1.2.3:^*

allow-newer is often used in conjunction with a constraint (in the constraints field) forcing the usage of a specific, newer version of a package.

The command line variant of this field is e.g. --allow-newer=bar. A bare --allow-newer is equivalent to --allow-newer=all.

allow-older: none, all, list of scoped package names (space or comma separated)

--allow-older , --allow-older=[none, all , [scope:][^]pkg] 

Since:: Cabal 2.0
Default value:: none

Like allow-newer, but applied to lower bounds rather than upper bounds.

The command line variant of this field is --allow-older=all. A bare --allow-older is equivalent to --allow-older=all.

index-state: HEAD, unix-timestamp, ISO8601 UTC timestamp.

Since:: Cabal 2.0
Default value:: HEAD

This allows to change the source package index state the solver uses to compute install-plans. This is particularly useful in combination with freeze-files in order to also freeze the state the package index was in at the time the install-plan was frozen.

-- UNIX timestamp format example
index-state: @1474739268

-- ISO8601 UTC timestamp format example
-- This format is used by 'cabal configure'
-- for storing `--index-state` values.
index-state: 2016-09-24T17:47:48Z

-- Specify different index-states per package repository
-- Supported since 3.4
index-state:
  , hackage.haskell.org 2020-05-06T22:33:27Z
  , head.hackage 2020-04-29T04:11:05Z

active-repositories: reponame1, reponame2

Synopsis:: Specify active package repositories
Since:: 3.4
Default value:: :rest

Specifies which of the package repositories defined in the configuration should be active. It’s also useful for specifying the order and the way active repositories are merged.

When searching for a certain version of a certain package name, the list of active repositories is searched last-to-first.

For example, suppose hackage.haskell.org has versions 1.0 and 2.0 of package X, and my-repository has version 2.0 of a similarly named package. Then, with the following configuration:

-- Force my-repository to be the first repository considered
active-repositories:
  , hackage.haskell.org
  , my-repository

version 2.0 of X will come from my-repository, and version 1.0 will come from hackage.haskell.org.

If we want to make a repository the sole provider of certain packages, we can put it last in the active repositories list, and add the :override modifier.

For example, if we modify the previous example like this:

active-repositories:
  , hackage.haskell.org
  , my-repository:override

then version 1.0 of package X won’t be found in any case, because X is present in my-repository only in version 2.0, and the :override forbids searching for other versions of X further up the list.

:override has no effect for package names that aren’t present in the overriding repository.

The special repository reference :rest stands for “all the other repositories” and can be useful to avoid lengthy lists of repository names:

-- Force my-repository to be the first repository considered
active-repositories: :rest, my-repository

The special repository reference :none disables all repositories, effectively putting cabal in “offline” mode:

active-repositories: :none

reject-unconstrained-dependencies: all, none

--reject-unconstrained-dependencies=[all|none]

Default value:: none
Since:: 2.6

By default, the dependency solver can include any package that it’s aware of in a build plan. If you wish to restrict the build plan to a closed set of packages (e.g., from a freeze file), use this flag.

When set to all, all non-local packages that aren’t goals must be explicitly constrained. When set to none, the solver will consider all packages.

7.6. Package configuration options

Package options affect the building of specific packages. There are three ways a package option can be specified:

They can be specified at the top-level, in which case they apply only to local package, or
They can be specified inside a package stanza, in which case they apply to the build of the package, whether or not it is local or external.
They can be specified inside an package * stanza, in which case they apply to all packages, local ones from the project and also external dependencies.

For example, the following options specify that optimization should be turned off for all local packages, and that bytestring (possibly an external dependency) should be built with -fno-state-hack:

optimization: False

package bytestring
    ghc-options: -fno-state-hack

ghc-options is not specifically described in this documentation, but is one of many fields for configuring programs. They take the form progname-options and progname-location, and can be set for all local packages in a program-options stanza or under a package stanza.

On the command line, these options are applied to all local packages. There is no per-package command line interface.

Some flags were added by more recent versions of the Cabal library. This means that they are NOT supported by packages which use Custom setup scripts that require a version of the Cabal library older than when the feature was added.

flags: list of +flagname or -flagname (space separated)

--flags="+foo -bar", -ffoo , -f-bar 

Force all flags specified as +flagname to be true, and all flags specified as -flagname to be false. For example, to enable the flag foo and disable bar, set:

flags: +foo -bar

Exactly one of + or - is required before each flag.

Flags are per-package, so it doesn’t make much sense to specify flags at the top-level, unless you happen to know that all of your local packages support the same named flags. If a flag is not supported by a package, it is ignored.

See also the solver configuration field constraints.

The command line variant of this flag is --flags. There is also a shortened form -ffoo -f-bar.

A common mistake is to say cabal build -fhans, where hans is a flag for a transitive dependency that is not in the local package; in this case, the flag will be silently ignored. If haskell-tor is the package you want this flag to apply to, try --constraint="haskell-tor +hans" instead.

with-compiler: executable

--with-compiler=executable

Specify the path to a particular compiler to be used. If not an absolute path, it will be resolved according to the PATH environment. The type of the compiler (GHC, GHCJS, etc) must be consistent with the setting of the compiler field.

The most common use of this option is to specify a different version of your compiler to be used; e.g., if you have ghc-7.8 in your path, you can specify with-compiler: ghc-7.8 to use it.

This flag also sets the default value of with-hc-pkg, using the heuristic that it is named ghc-pkg-7.8 (if your executable name is suffixed with a version number), or is the executable named ghc-pkg in the same directory as the ghc directory. If this heuristic does not work, set with-hc-pkg explicitly.

For inplace packages, cabal build maintains a separate build directory for each version of GHC, so you can maintain multiple build trees for different versions of GHC without clobbering each other.

It’s not possible to set with-compiler on a per-package basis.

The command line variant of this flag is --with-compiler=ghc-7.8; there is also a short version -w ghc-7.8.

with-hc-pkg: executable

--with-hc-pkg=executable

Specify the path to the package tool, e.g., ghc-pkg. This package tool must be compatible with the compiler specified by with-compiler (generally speaking, it should be precisely the tool that was distributed with the compiler). If this option is omitted, the default value is determined from with-compiler.

The command line variant of this flag is --with-hc-pkg=ghc-pkg-7.8.

optimization: nat

--enable-optimization 

--disable-optimization 

Default value:: 1

Build with optimization. This is appropriate for production use, taking more time to build faster libraries and programs.

The optional nat value is the optimisation level. Some compilers support multiple optimisation levels. The range is 0 to 2. Level 0 disables optimization, level 1 is the default. Level 2 is higher optimisation if the compiler supports it. Level 2 is likely to lead to longer compile times and bigger generated code. If you are not planning to run code, turning off optimization will lead to better build times and less code to be rebuilt when a module changes.

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

We also accept True (equivalent to 1) and False (equivalent to 0).

Note that as of GHC 8.0, GHC does not recompile when optimization levels change (see GHC issue #10923), so if you change the optimization level for a local package you may need to blow away your old build products in order to rebuild with the new optimization level.

The command line variant of this flag is -O2 (with -O1 equivalent to -O). There are also long-form variants --enable-optimization and --disable-optimization.

configure-options: args (space separated)

--configure-option=arg

A list of extra arguments to pass to the external ./configure script, if one is used. This is only useful for packages which have the Configure build type. See also the section on System-dependent parameters.

The command line variant of this flag is --configure-option=arg, which can be specified multiple times to pass multiple options.

compiler: ghc, ghcjs, jhc, lhc, uhc or haskell-suite

--compiler=compiler

Default value:: ghc

Specify the compiler toolchain to be used. This is independent of with-compiler, because the choice of toolchain affects Cabal’s build logic.

The command line variant of this flag is --compiler=ghc.

It’s not possible to set compiler on a per-package basis.

tests: boolean

--enable-tests 

--disable-tests 

Default value:: False

Force test suites to be enabled. For most users this should not be needed, as we always attempt to solve for test suite dependencies, even when this value is False; furthermore, test suites are automatically enabled if they are requested as a built target.

The command line variant of this flag is --enable-tests and --disable-tests.

benchmarks: boolean

--enable-benchmarks 

--disable-benchmarks 

Default value:: False

Force benchmarks to be enabled. For most users this should not be needed, as we always attempt to solve for benchmark dependencies, even when this value is False; furthermore, benchmarks are automatically enabled if they are requested as a built target.

The command line variant of this flag is --enable-benchmarks and --disable-benchmarks.

extra-prog-path: paths (newline or comma separated)

--extra-prog-path=PATH

Since:: Cabal 1.18

A list of directories to search for extra required programs. Most users should not need this, as programs like happy and alex will automatically be installed and added to the path. This can be useful if a Custom setup script relies on an exotic extra program.

The command line variant of this flag is --extra-prog-path=PATH, which can be specified multiple times.

run-tests: boolean

--run-tests 

Default value:: False

Run the package test suite upon installation. This is useful for saying “When this package is installed, check that the test suite passes, terminating the rest of the build if it is broken.”

Warning

One deficiency: the run-tests setting of a package is NOT recorded as part of the hash, so if you install something without run-tests and then turn on run-tests, we won’t subsequently test the package. If this is causing you problems, give us a shout.

The command line variant of this flag is --run-tests.

7.6.1. Object code options

debug-info: integer

--enable-debug-info=⟨n⟩

--disable-debug-info 

Since:: Cabal 1.22
Default value:: False

If the compiler (e.g., GHC 7.10 and later) supports outputting OS native debug info (e.g., DWARF), setting debug-info: True will instruct it to do so. See the GHC wiki page on DWARF for more information about this feature.

(This field also accepts numeric syntax, but until GHC 8.2 this didn’t do anything.)

The command line variant of this flag is --enable-debug-info and --disable-debug-info.

split-sections: boolean

--enable-split-sections 

--disable-split-sections 

Since:: Cabal 2.2
Default value:: False

Use the GHC -split-sections 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 a bit more memory.

This feature is supported by GHC 8.0 and later.

The command line variant of this flag is --enable-split-sections and --disable-split-sections.

split-objs: boolean

--enable-split-objs 

--disable-split-objs 

Default value:: False

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.

It is generally recommend that you use split-sections instead of split-objs where possible.

The command line variant of this flag is --enable-split-objs and --disable-split-objs.

executable-stripping: boolean

--enable-executable-stripping 

--disable-executable-stripping 

Default value:: True

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.

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

If debug-info is set explicitly then executable-stripping is set to False as otherwise all the debug symbols will be stripped.

The command line variant of this flag is --enable-executable-stripping and --disable-executable-stripping.

library-stripping: boolean

--enable-library-stripping 

--disable-library-stripping 

Since:: Cabal 1.20

When installing binary libraries, run the strip program on the binary, saving space on the file system. See also executable-stripping.

If debug-info is set explicitly then library-stripping is set to False as otherwise all the debug symbols will be stripped.

The command line variant of this flag is --enable-library-stripping and --disable-library-stripping.

7.6.2. Executable options

program-prefix: prefix

--program-prefix=prefix

Prepend *prefix* to installed program names. (Currently implemented in a silly and not useful way. If you need this to work give us a shout.)

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

The command line variant of this flag is --program-prefix=foo-.

program-suffix: suffix

--program-suffix=suffix

Append *suffix* to installed program names. (Currently implemented in a silly and not useful way. If you need this to work give us a shout.)

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

The command line variant of this flag is --program-suffix='$version'.

7.6.3. Dynamic linking options

shared: boolean

--enable-shared 

--disable-shared 

Default value:: False

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

The command line variant of this flag is --enable-shared and --disable-shared.

executable-dynamic: boolean

--enable-executable-dynamic 

--disable-executable-dynamic 

Default value:: False

Link executables dynamically. The executable’s library dependencies should be built as shared objects. This implies shared: True unless shared: False is explicitly specified.

The command line variant of this flag is --enable-executable-dynamic and --disable-executable-dynamic.

library-for-ghci: boolean

--enable-library-for-ghci 

--disable-library-for-ghci 

Default value:: True

Build libraries suitable for use with GHCi. This involves an extra linking step after the build.

Not all platforms support GHCi and indeed on some platforms, trying to build GHCi libs fails. In such cases, consider setting library-for-ghci: False.

The command line variant of this flag is --enable-library-for-ghci and --disable-library-for-ghci.

relocatable: 

--relocatable 

Since:: Cabal 1.22
Default value:: False

Build a package which is relocatable. (TODO: It is not clear what this actually does, or if it works at all.)

The command line variant of this flag is --relocatable.

7.6.4. Static linking options

static: boolean

--enable-static 

--disable-static 

Default value:: False

Roll this and all dependent libraries into a combined .a archive. This uses GHCs -staticlib flag, which is available for iOS and with GHC 8.4 and later for other platforms as well.

executable-static: boolean

--enable-executable-static 

--disable-executable-static 

Default value:: False

Build fully static executables. This links all dependent libraries into executables statically, including libc. This passes -static and -optl=-static to GHC.

7.6.5. Foreign function interface options

extra-include-dirs: directories (comma or newline separated list)

--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.

The command line variant of this flag is --extra-include-dirs=DIR, which can be specified multiple times.

extra-lib-dirs: directories (comma or newline separated list)

--extra-lib-dirs=DIR

An extra directory to search for system libraries files.

The command line variant of this flag is --extra-lib-dirs=DIR, which can be specified multiple times.

extra-framework-dirs: directories (comma or newline separated list)

--extra-framework-dirs=DIR

An extra directory to search for frameworks (OS X only).

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.

The command line variant of this flag is --extra-framework-dirs=DIR, which can be specified multiple times.

7.6.6. Profiling options

profiling: boolean

--enable-profiling 

--disable-profiling 

Since:: Cabal 1.22
Default value:: False

Build libraries and executables with profiling enabled (for compilers that support profiling as a separate mode). It is only necessary to specify profiling for the specific package you want to profile; cabal build will ensure that all of its transitive dependencies are built with profiling enabled.

To enable profiling for only libraries or executables, see library-profiling and executable-profiling.

For useful profiling, it can be important to control precisely what cost centers are allocated; see profiling-detail.

The command line variant of this flag is --enable-profiling and --disable-profiling.

profiling-detail: level

--profiling-detail=level

Since:: Cabal 1.24

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 field.

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, this is for non-inline functions. Corresponds to -fprof-auto-exported.
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. Corresponds to -fprof-auto-top.
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. Corresponds to -fprof-auto.
late-toplevel: Like top-level but costs will be assigned to top level definitions after optimization. This lowers profiling overhead massively while giving similar levels of detail as toplevle-functions. However it means functions introduced by GHC during optimization will show up in profiles as well. Corresponds to -fprof-late if supported and -fprof-auto-top otherwise.
late: Currently an alias for late-toplevel

The command line variant of this flag is --profiling-detail=none.

library-profiling-detail: level

--library-profiling-detail=level

Since:: Cabal 1.24

Like profiling-detail, but applied only to libraries

The command line variant of this flag is --library-profiling-detail=none.

library-vanilla: boolean

--enable-library-vanilla 

--disable-library-vanilla 

Default value:: True

Build ordinary libraries (as opposed to profiling libraries). Mostly, you can set this to False to avoid building ordinary libraries when you are profiling.

The command line variant of this flag is --enable-library-vanilla and --disable-library-vanilla.

library-profiling: boolean

--enable-library-profiling 

--disable-library-profiling 

Since:: Cabal 1.22
Default value:: False

Build libraries with profiling enabled. You probably want to use profiling instead.

The command line variant of this flag is --enable-library-profiling and --disable-library-profiling.

executable-profiling: boolean

--enable-executable-profiling 

--disable-executable-profiling 

Since:: Cabal 1.22
Default value:: False

Build executables with profiling enabled. You probably want to use profiling instead.

The command line variant of this flag is --enable-executable-profiling and --disable-executable-profiling.

7.6.7. Coverage options

coverage: boolean

--enable-coverage 

--disable-coverage 

Since:: Cabal 1.22
Default value:: False

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

The command line variant of this flag is --enable-coverage and --disable-coverage.

library-coverage: boolean

--enable-library-coverage 

--disable-library-coverage 

Deprecated:
Since:: Cabal 1.22
Default value:: False

Deprecated, use coverage.

The command line variant of this flag is --enable-library-coverage and --disable-library-coverage.

7.6.8. Haddock options

documentation: boolean

--enable-documentation 

--disable-documentation 

Default value:: False

Enables building of Haddock documentation. Implied when calling cabal haddock.

The command line variant of this flag is --enable-documentation and --disable-documentation.

documentation: true does not imply haddock-all, haddock-benchmarks, haddock-executables, haddock-internal or haddock-tests. These need to be enabled separately if desired.

doc-index-file: templated path
--doc-index-file=TEMPLATE: A central index of Haddock API documentation (template cannot use $pkgid), which should be updated as documentation is built.

The following commands are equivalent to ones that would be passed when running setup haddock.

haddock-hoogle: boolean

--haddock-hoogle 

Default value:: False

Generate a text file which can be converted by Hoogle into a database for searching. This is equivalent to running haddock with the --hoogle flag.

haddock-html: boolean

--haddock-html 

Default value:: True

Build HTML documentation.

haddock-quickjump: boolean

--haddock-quickjump 

Default value:: False

Generate an index for interactive documentation navigation. This is equivalent to running haddock with the --quickjump flag.

haddock-html-location: templated path

--haddock-html-location=TEMPLATE

Specify a template for the location of HTML documentation for prerequisite packages. The substitutions 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:

html-location: http://hackage.haskell.org/packages/archive/$pkg/latest/doc/html

If passed on the command line, the argument may be quoted to prevent substitution by the shell.

--html-location='http://hackage.haskell.org/packages/archive/$pkg/latest/doc/html'

If this option is omitted, the location for each package is obtained using the package tool (e.g. ghc-pkg).

haddock-executables: boolean

--haddock-executables 

Default value:: False

Run haddock on all executable programs.

haddock-tests: boolean

--haddock-tests 

Default value:: False

Run haddock on all test suites.

haddock-benchmarks: boolean

--haddock-benchmarks 

Default value:: False

Run haddock on all benchmarks.

haddock-internal: boolean

--haddock-internal 

Default value:: False

Build haddock documentation which includes unexposed modules and symbols.

haddock-all: boolean

--haddock-all 

Default value:: False

Run haddock on all components.

haddock-css: path
--haddock-css=PATH: The CSS file that should be used to style the generated documentation (overriding haddock’s default).

haddock-hyperlink-source: boolean

--haddock-hyperlink-source 

Default value:: False

Generated hyperlinked source code using HsColour, and have Haddock documentation link to it. This is equivalent to running haddock with the --hyperlinked-source flag.

haddock-hscolour-css: path
--haddock-hscolour-css=PATH: The CSS file that should be used to style the generated hyperlinked source code (from HsColour).

haddock-contents-location: URL
--haddock-contents-location=URL: A baked-in URL to be used as the location for the contents page.

haddock-keep-temp-files: boolean

Keep temporary files.

There is no command line variant of this flag.

open: boolean
--open : When generating HTML documentation, attempt to open it in a browser when complete. This will use xdg-open on Linux and BSD systems, open on macOS, and start on Windows.

7.7. Advanced global configuration options

write-ghc-environment-files: always, never, or ghc8.4.4+

--write-ghc-environment-files=policy

Default value:: never

Whether a GHC package environment file should be created after a successful build.

Since Cabal 3.0, defaults to never. Before that, defaulted to creating them only when compiling with GHC 8.4.4 and older (GHC 8.4.4 is the first version that supports the -package-env - option that allows ignoring the package environment files).

build-info: True, False

--enable-build-info 

--disable-build-info 

Default value:: False

Enable generation of build information for Cabal components. Contains very detailed information on how to build an individual component, such as compiler version, modules of a component and how to compile the component.

The output format is in json, and the exact location can be discovered from plan.json, where it is identified by build-info within the items in the install-plan. Note, that this field in plan.json can be null, if and only if build-type: Custom is set, and the Cabal version is too old (i.e. < 3.7). If the field is missing entirely, the component is not a local one, thus, no build-info exists for that particular component within the install-plan.

Note

The format and fields of the generated build information is currently experimental, in the future we might add or remove fields, depending on the needs of other tooling.

http-transport: curl, wget, powershell, or plain-http

--http-transport=transport

Default value:: curl

Set a transport to be used when making http(s) requests.

The command line variant of this field is --http-transport=curl.

ignore-expiry: boolean

--ignore-expiry 

Default value:: False

If True, we will ignore expiry dates on metadata from Hackage.

In general, you should not set this to True as it will leave you vulnerable to stale cache attacks. However, it may be temporarily useful if the main Hackage server is down, and we need to rely on mirrors which have not been updated for longer than the expiry period on the timestamp.

The command line variant of this field is --ignore-expiry.

remote-repo-cache: directory

--remote-repo-cache=DIR

Default value:: ~/.cabal/packages

The location where packages downloaded from remote repositories will be cached. Not implemented yet.

The command line variant of this flag is --remote-repo-cache=DIR.

logs-dir: directory

--logs-dir=DIR

Default value:: ~/.cabal/logs

The location where build logs for packages are stored. Not implemented yet.

The command line variant of this flag is --logs-dir=DIR.

build-summary: template filepath

--build-summary=TEMPLATE

Default value:: ~/.cabal/logs/build.log

The file to save build summaries. Not implemented yet.

Valid variables which can be used in the path are $pkgid, $compiler, $os and $arch.

The command line variant of this flag is --build-summary=TEMPLATE.

Undocumented fields: root-cmd, symlink-bindir, build-log, remote-build-reporting, report-planned-failure, offline.

7.7.1. Advanced solver options

Most users generally won’t need these.

solver: modular

--solver=modular

This field is reserved to allow the specification of alternative dependency solvers. At the moment, the only accepted option is modular.

The command line variant of this field is --solver=modular.

max-backjumps: nat

--max-backjumps=N

Default value:: 4000

Maximum number of backjumps (backtracking multiple steps) allowed while solving. Set -1 to allow unlimited backtracking, and 0 to disable backtracking completely.

The command line variant of this field is --max-backjumps=4000.

reorder-goals: boolean

--reorder-goals 

--no-reorder-goals 

Default value:: False

When enabled, the solver will reorder goals according to certain heuristics. Slows things down on average, but may make backtracking faster for some packages. It’s unlikely to help for small projects, but for big install plans it may help you find a plan when otherwise this is not possible. See issue #1780 for more commentary.

The command line variant of this field is --(no-)reorder-goals.

count-conflicts: boolean

--count-conflicts 

--no-count-conflicts 

Default value:: True

Try to speed up solving by preferring goals that are involved in a lot of conflicts.

The command line variant of this field is --(no-)count-conflicts.

fine-grained-conflicts: boolean

--fine-grained-conflicts 

--no-fine-grained-conflicts 

Default value:: True

When enabled, the solver will skip a version of a package if it does not resolve any of the conflicts encountered in the last version of that package. For example, if foo-1.2 depended on bar, and the solver couldn’t find consistent versions for bar’s dependencies, then the solver would skip foo-1.1 if it also depended on bar.

The command line variant of this field is --(no-)fine-grained-conflicts.

minimize-conflict-set: boolean

--minimize-conflict-set 

--no-minimize-conflict-set 

Default value:: False

When there is no solution, try to improve the solver error message by finding a minimal conflict set. This option may increase run time significantly, so it is off by default.

The command line variant of this field is --(no-)minimize-conflict-set.

strong-flags: boolean

--strong-flags 

--no-strong-flags 

Default value:: False

Do not defer flag choices. (TODO: Better documentation.)

The command line variant of this field is --(no-)strong-flags.

allow-boot-library-installs: boolean

--allow-boot-library-installs 

--no-allow-boot-library-installs 

Default value:: False

By default, the dependency solver doesn’t allow base, ghc-prim, integer-simple, integer-gmp, and template-haskell to be installed or upgraded. This flag removes the restriction.

The command line variant of this field is --(no-)allow-boot-library-installs.

cabal-lib-version: version

--cabal-lib-version=version

This field selects the version of the Cabal library which should be used to build packages. This option is intended primarily for internal development use (e.g., forcing a package to build with a newer version of Cabal, to test a new version of Cabal.) (TODO: Specify its semantics more clearly.)

The command line variant of this field is --cabal-lib-version=1.24.0.1.

prefer-oldest: boolean

--prefer-oldest 

--no-prefer-oldest 

Since:: Cabal 3.10
Default value:: False

By default, when solver has a choice of multiple versions of the same package, it will first try to derive a build plan with the latest version. This flag switches the behaviour, making the solver to prefer the oldest packages available.

The primary use case is to help users in establishing lower bounds of upstream dependencies.

The command line variant of this field is --(no-)prefer-oldest.