8. 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:

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 v2-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):

  1. ~/.cabal/config (the user-wide global configuration)

  2. cabal.project (the project configuration)

  3. cabal.project.freeze (the output of cabal v2-freeze)

  4. cabal.project.local (the output of cabal v2-configure)

8.1. 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

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

  1. They can specify a Cabal file, or a directory containing a Cabal file, e.g., packages: Cabal cabal-install/cabal-install.cabal.

  2. They can specify a 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}/

  3. 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 #3585.

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)

[STRIKEOUT:Specifies a list of external packages from Hackage which should be considered local packages.] (Not implemented)

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 v2-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)

8.1.1. 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)
type: 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.

8.2. 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.

--store-dir=DIR

Specifies the name of the directory of the global package store.

8.3. Solver configuration options

The following settings control the behavior of the dependency solver:

constraints: constraints list (comma separated)
--constraint="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 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 v2-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 v2-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

This allows to specify the active package repositories, when multiple are specified. This is useful as you can specify the order and the way active repositories are merged.

-- for packages in head.hackage
-- only versions in head.hackage are considered
active-repositories:
  , hackage.haskell.org
  , head.hackage:override

-- Force head.hackage to be the primary repository considered
active-repositories: :rest, head.hackage

-- "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.

8.4. 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 only be set inside package stanzas. (TODO: They are not supported at top-level, see #3579.)

At the moment, there is no way to specify an option to apply to all external packages or all inplace packages. Additionally, it is only possible to specify these options on the command line for 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 v2-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 v2-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.

At the moment, it’s not possible to set with-compiler on a per-package basis, but eventually we plan on relaxing this restriction. If this is something you need, give us a shout.

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 #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.

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.

8.4.1. 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 outputing 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.

8.4.2. Executable options

program-prefix: prefix
--program-prefix=prefix

[STRIKEOUT: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

[STRIKEOUT: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'.

8.4.3. 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

[STRIKEOUT: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.

8.4.4. 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.

8.4.5. 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.

8.4.6. 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 v2-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.

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.

8.4.7. 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.

8.4.8. Haddock options

documentation: boolean
--enable-documentation
--disable-documentation
Default value

False

Enables building of Haddock documentation

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

documentation: true does not imply 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 command line variant of this flag is --doc-index-file=TEMPLATE

The following commands are equivalent to ones that would be passed when running setup haddock. (TODO: Where does the documentation get put.)

haddock-hoogle: boolean
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.

The command line variant of this flag is --hoogle (for the haddock command).

haddock-html: boolean
Default value

True

Build HTML documentation.

The command line variant of this flag is --html (for the haddock command).

haddock-html-location: templated path
--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

The command line variant of this flag is --html-location (for the haddock subcommand).

--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).

haddock-executables: boolean
Default value

False

Run haddock on all executable programs.

The command line variant of this flag is --executables (for the haddock subcommand).

haddock-tests: boolean
Default value

False

Run haddock on all test suites.

The command line variant of this flag is --tests (for the haddock subcommand).

haddock-benchmarks: boolean
Default value

False

Run haddock on all benchmarks.

The command line variant of this flag is --benchmarks (for the haddock subcommand).

haddock-all: boolean
Default value

False

Run haddock on all components.

The command line variant of this flag is --all (for the haddock subcommand).

haddock-internal: boolean
Default value

False

Build haddock documentation which includes unexposed modules and symbols.

The command line variant of this flag is --internal (for the haddock subcommand).

haddock-css: path

The CSS file that should be used to style the generated documentation (overriding haddock’s default.)

The command line variant of this flag is --css (for the haddock subcommand).

Default value

False

Generated hyperlinked source code using HsColour, and have Haddock documentation link to it.

The command line variant of this flag is --hyperlink-source (for the haddock subcommand).

haddock-hscolour-css: path

The CSS file that should be used to style the generated hyperlinked source code (from HsColour).

The command line variant of this flag is --hscolour-css (for the haddock subcommand).

haddock-contents-location: URL

A baked-in URL to be used as the location for the contents page.

The command line variant of this flag is --contents-location (for the haddock subcommand).

haddock-keep-temp-files: boolean

Keep temporary files.

The command line variant of this flag is --keep-temp-files (for the haddock subcommand).

8.5. 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).

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

[STRIKEOUT: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

[STRIKEOUT: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

[STRIKEOUT:The file to save build summaries. Valid variables which can be used in the path are $pkgid, $compiler, $os and $arch.] Not implemented yet.

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

world-file: path
--world-file=FILE
Deprecated

[STRIKEOUT:The location of the world file.] Deprecated.

The command line variant of this flag is --world-file=FILE.

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

8.5.1. 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 #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.