# Configuration and customisation Stack is configured by the content of YAML files. Some Stack operations can also be customised by the use of scripts. ## YAML configuration Stack's YAML configuration options break down into [project-specific](#project-specific-configuration) options and [non-project-specific](#non-project-specific-configuration) options. They are configured at the project-level or globally. The **project-level** configuration file (`stack.yaml`) contains project-specific options and may contain non-project-specific options. However, non-project-specific options in the project-level configuration file in the `global-project` directory (see below) are ignored by Stack. Stack obtains project-level configuration from one of the following (in order of preference): 1. A file specified by the `--stack-yaml` command line option. 2. A file specified by the `STACK_YAML` environment variable. 3. A file named `stack.yaml` in the current directory or an ancestor directory. 4. A file name `stack.yaml` in the `global-project` directory in the [Stack root](stack_root.md). The **global** configuration file (`config.yaml`) contains only non-project-specific options. Stack obtains global configuration from a file named `config.yaml`. The location of this file depends on the operating system and whether Stack is configured to use the XDG Base Directory Specification. === "Unix-like" `config.yaml` is located in `/etc/stack` (for system-wide options); and/or in the [Stack root](stack_root.md) (for user-specific options). === "Windows" `config.yaml` is located in the [Stack root](stack_root.md). === "XDG Base Directory Specification" On Unix-like operating systems and Windows, Stack can be configured to follow the XDG Base Directory Specification if the environment variable `STACK_XDG` is set to any non-empty value. However, Stack will ignore that configuration if the [Stack root](stack_root.md) location has been set on the command line or the `STACK_ROOT` environment variable exists. If Stack is following the XDG Base Directory Specification, the location of `config.yaml` (for user-specific options) is `/stack`. If the `XDG_CONFIG_HOME` environment variable does not exist, the default is `~/.config/stack` on Unix-like operating systems and `%APPDIR%\stack` on Windows. This page is intended to document fully all YAML configuration options. If you identify any inaccuracies or incompleteness, please update the page, and if you're not sure how, open an issue labeled "question". If you wish to understand the difference between a `stack.yaml` files and a Cabal file (named `.cabal`), see the [stack.yaml vs a Cabal file](stack_yaml_vs_cabal_package_file.md) documentation. ## Project-specific configuration Project-specific configuration options are valid only in a project-level configuration file (`stack.yaml`). > Note: We define **project** to mean a directory that contains a `stack.yaml` > file, which specifies how to build a set of packages. We define **package** to > be a package with a Cabal file or an Hpack `package.yaml` file. In your project-specific options, you specify both **which local packages** to build and **which dependencies to use** when building these packages. Unlike the user's local packages, these dependencies aren't built by default. They only get built when needed. Shadowing semantics, described [here](https://docs.haskellstack.org/en/v1.5.1/architecture/#shadowing), are applied to your configuration. So, if you add a package to your `packages` list, it will be used even if you're using a snapshot that specifies a particular version. Similarly, `extra-deps` will shadow the version specified in the resolver. ### resolver or snapshot Command line equivalent (takes precedence): `--resolver` option `resolver` and `snapshot` are synonyms. Only one of these keys is permitted, not both. The `resolver` or `snapshot` key specifies which snapshot is to be used for this project. A snapshot defines a GHC version, a number of packages available for installation, and various settings like build flags. It is called a resolver since a snapshot states how dependencies are resolved. There are currently four resolver types: * LTS Haskell snapshots, e.g. `resolver: lts-21.13` * Stackage Nightly snapshots, e.g. `resolver: nightly-2023-09-24` * No snapshot, just use packages shipped with the compiler. For GHC this looks like `resolver: ghc-9.6.2` * Custom snapshot, via a URL or relative file path. For further information, see the [Pantry](pantry.md) documentation. Each of these resolvers will also determine what constraints are placed on the compiler version. See the [compiler-check](#compiler-check) option for some additional control over compiler version. The `resolver` key corresponds to a Pantry snapshot location. For further information, see the [Pantry](pantry.md) documentation. ### packages Default: ~~~yaml packages: - . ~~~ The `packages` key specifies a list of packages that are part of your local project. These are specified via paths to local directories. A path is considered relative to the directory containing the `stack.yaml` file. For example, if the `stack.yaml` is located at `/dir1/dir2/stack.yaml`, and has: ~~~yaml packages: - my-package - dir3/my-other-package ~~~ the configuration means "project packages in directories `/dir1/dir2/my-package` and `/dir1/dir2/dir3/my-other-package`". The `packages` key is optional. The default value, '`.`', means that the project has a single package located in the current directory. Each specified package directory must have a valid Cabal file or Hpack `package.yaml` file present. Any subdirectories of the directory are not searched for Cabal files. A subdirectory has to be specified as an independent item in the list of packages. A project package is different from a dependency, both a snapshot dependency (via the [`resolver` or `snapshot`](#resolver-or-snapshot) key) and an extra-deps dependency (via the [`extra-deps`](#extra-deps) key). For example: * a project package will be built by default by commanding [`stack build`](build_command.md) without specific targets. A dependency will only be built if it is depended upon; and * test suites and benchmarks may be run for a project package. They are never run for a dependency. ### extra-deps Default: `[]` The `extra-deps` key specifies a list of extra dependencies on top of what is defined in the snapshot (specified by the [`resolver` or `snapshot`](#resolver-or-snapshot) key). A dependency may come from either a Pantry package location or a local file path. A Pantry package location is one or three different kinds of sources: * the package index (Hackage); * an archive (a tarball or zip file, either local or over HTTP or HTTPS); or * a Git or Mercurial repository. For further information on the format for specifying a Pantry package location, see the [Pantry](pantry.md) documentation. For example: ~~~yaml extra-deps: # The latest revision of a package in the package index (Hackage): - acme-missiles-0.3 # A specific revision of a package in the package index (Hackage): - acme-missiles-0.3@rev:0 # An *.tar.gz archive file over HTTPS: - url: https://github.com/example-user/my-repo/archive/08c9b4cdf977d5bcd1baba046a007940c1940758.tar.gz subdirs: - my-package # A Git repository at a specific commit: - git: https://github.com/example-user/my-repo.git commit: 08c9b4cdf977d5bcd1baba046a007940c1940758 # An archive of files at a point in the history of a GitHub repository # (identified by a specific commit): - github: example-user/my-repo commit: 08c9b4cdf977d5bcd1baba046a007940c1940758 subdirs: - my-package ~~~ !!! note GHC boot packages are special. An extra-dep with the same package name and version as a GHC boot package will be ignored. For a local file path source, the path is considered relative to the directory containing the `stack.yaml` file. For example, if the `stack.yaml` is located at `/dir1/dir2/stack.yaml`, and has: ~~~yaml extra-deps: - my-package - dir3/my-other-package ~~~ the configuration means "extra-deps packages in directories `/dir1/dir2/my-package` and `/dir1/dir2/dir3/my-other-package`". !!! note A local file path that has the format of a package identifier will be interpreted as a reference to a package on Hackage. Prefix it with `./` to avoid that confusion. !!! note A specified extra-dep that does not have the format of a valid Pantry package location (for example, a reference to a package on Hackage that omits the package's version) will be interpreted as a local file path. ### flags Default: `{}` Command line equivalent (takes precedence): `stack build --flag` option Flags can be set for each package separately. For example: ~~~yaml flags: package-name: flag-name: true ~~~ If a specified flag is different than the one specified for a snapshot package, then the snapshot package will automatically be promoted to be an extra-dep. ### drop-packages [:octicons-tag-24: 2.1.1](https://github.com/commercialhaskell/stack/releases/tag/v2.1.1) Default: `[]` Packages which, when present in the snapshot specified in `resolver`, should not be included in our package. This can be used for a few different purposes, e.g.: * Ensure that packages you don't want used in your project cannot be used in a `package.yaml` file (e.g., for license reasons) * Prevent overriding of a global package like `Cabal`. For more information, see Stackage issue [#4425](https://github.com/commercialhaskell/stackage/issues/4425) * When using a custom GHC build, avoid incompatible packages (see this [comment](https://github.com/commercialhaskell/stack/pull/4655#issuecomment-477954429)). ~~~yaml drop-packages: - Cabal - buggy-package - package-with-unacceptable-license ~~~ ### user-message If present, specifies a message to be displayed every time the configuration is loaded by Stack. It can serve as a reminder for the user to review the configuration and make any changes if needed. The user can delete this message if the generated configuration is acceptable. For example, a user-message is inserted by `stack init` when it omits packages or adds external dependencies, namely: ~~~yaml user-message: ! 'Warning: Some packages were found to be incompatible with the resolver and have been left commented out in the packages section. Warning: Specified resolver could not satisfy all dependencies. Some external packages have been added as dependencies. You can omit this message by removing it from stack.yaml ' ~~~ ### custom-preprocessor-extensions Default: `[]` Command line equivalent: `--customer-preprocessor-extensions` option In order for Stack to be aware of any custom preprocessors you are using, add their extensions here ~~~yaml custom-preprocessor-extensions: - erb ~~~ TODO: Add a simple example of how to use custom preprocessors. ## Non-project-specific configuration Non-project configuration options can be included in a project-level configuration file (`stack.yaml`) or in global configuration files (`config.yaml`). However, non-project-specific options in the project-level configuration file in the `global-project` directory are ignored by Stack. The options below are listed in alphabetic order. ### allow-different-user [:octicons-tag-24: 1.0.1.0](https://github.com/commercialhaskell/stack/releases/tag/v1.0.1.0) Restrictions: POSIX systems only. Default: `false` Command line equivalent (takes precedence): `--[no-]allow-different-user` flag Allow users other than the owner of the [Stack root](stack_root.md) to use the Stack installation. ~~~yaml allow-different-user: true ~~~ The intention of this option is to prevent file permission problems, for example as the result of a Stack command executed under `sudo`. The option is automatically enabled when Stack is re-spawned in a Docker process. ### allow-newer [:octicons-tag-24: 0.1.8.0](https://github.com/commercialhaskell/stack/releases/tag/v0.1.8.0) Default: `false` Whether to ignore version bounds in Cabal files. This also ignores lower bounds. The name `allow-newer` is chosen to match the commonly-used Cabal option. ~~~yaml allow-newer: true ~~~ ### allow-newer-deps :octicons-beaker-24: Experimental [:octicons-tag-24: 2.9.3](https://github.com/commercialhaskell/stack/releases/tag/v2.9.3) Default: `none` Determines a subset of packages to which `allow-newer` should apply. This option has no effect (but warns) if `allow-newer` is `false`. ~~~yaml allow-newer-deps: - foo - bar ~~~ ### apply-ghc-options [:octicons-tag-24: 0.1.6.0](https://github.com/commercialhaskell/stack/releases/tag/v0.1.6.0) Default: `locals` Related command line: [`stack build --ghc-options`](build_command.md#-ghc-options-option) option Determines to which packages any GHC command line options specified on the command line are applied. Possible values are: `everything` (all packages, local or otherwise), `locals` (all local packages, targets or otherwise), and `targets` (all local packages that are targets). !!! note The use of `everything` can break invariants about your snapshot database. !!! note Before Stack 0.1.6.0, the default value was `targets`. ### apply-prog-options [:octicons-tag-24: 2.11.1](https://github.com/commercialhaskell/stack/releases/tag/v2.11.1) Default: `locals` Related command line: [`stack build --PROG-option`](build_command.md#-prog-option-options) options Determines to which packages all and any `--PROG-option` command line options specified on the command line are applied. Possible values are: `everything` (all packages, local or otherwise), `locals` (all local packages, targets or otherwise), and `targets` (all local packages that are targets). !!! note The use of `everything` can break invariants about your snapshot database. ### arch Default: The machine architecture on which Stack is running. Command line equivalent (takes precedence): `--arch` option Stack identifies different GHC executables by platform (operating system and machine architecture), (optional) GHC variant and (optional) GHC build. See [`setup-info`](#setup-info). `arch` sets the machine architecture. Values are those recognized by Cabal, including `x86_64`, `i386` and `aarch64`. ### build [:octicons-tag-24: 1.1.0](https://github.com/commercialhaskell/stack/releases/tag/v1.1.0) Default: ~~~yaml build: library-profiling: false executable-profiling: false copy-bins: false prefetch: false keep-going: false keep-tmp-files: false # NOTE: global usage of haddock can cause build failures when documentation is # incorrectly formatted. This could also affect scripts which use Stack. haddock: false haddock-arguments: # Additional arguments passed to haddock. The corresponding command line # option is --haddock-arguments. Example of use: # # haddock-args: # - "--css=/home/user/my-css" haddock-args: [] # The corresponding command line flag is --[no-]open. open-haddocks: false # If Stack is configured to build Haddock documentation, defaults to true. haddock-deps: false # If specified, implies haddock-internal: false and # haddock-hyperlink-source: true. Since Stack UNRELEASED. haddock-for-hackage: false # The configuration is ignored, if haddock-for-hackage: true. haddock-internal: false # The configuration is ignored, if haddock-for-hackage: true. haddock-hyperlink-source: true # These are inadvisable to use in your global configuration, as they make the # Stack build command line behave quite differently. test: false test-arguments: rerun-tests: true # Rerun successful tests # The corresponding command line option is --test-arguments. Example of use: # # additional-args: # - "--fail-fast" additional-args: [] coverage: false no-run-tests: false bench: false benchmark-opts: # Example of use: # # benchmark-arguments: "--csv bench.csv" benchmark-arguments: "" no-run-benchmarks: false force-dirty: false reconfigure: false cabal-verbose: false split-objs: false # Since Stack 1.8. Starting with Stack 2.0, the default is true interleaved-output: true # Since Stack 2.13.1. Available options are none, count-only, capped and full. progress-bar: capped # Since Stack 1.10. ddump-dir: "" ~~~ Command line equivalents (take precedence): Yes, see below. Allows setting build options which are usually specified on the command line. The meanings of these settings correspond directly with the command line flags of the same name. For further information, see the [`stack build` command](build_command.md) documentation and the [users guide](GUIDE.md#the-build-command). ### casa [:octicons-tag-24: 2.13.1](https://github.com/commercialhaskell/stack/releases/tag/v2.13.1) Default: ~~~yaml casa: enable: true # Use a Casa server? repo-prefix: https://casa.fpcomplete.com # Unless casa-repo-prefix is set. max-keys-per-request: 1280 # Maximum number of keys per request. ~~~ This option specifies whether or not Stack should use a Casa (content-addressable storage archive) server to cache Cabal files and all other files in packages; and, if so, the prefix for the URL used to pull information from the server and the maximum number of keys per request. For further information, see this blog post about [Casa and Stack](https://www.fpcomplete.com/blog/casa-and-stack/). `repo-prefix` replaces [`casa-repo-prefix`](#casa-repo-prefix) (which is deprecated) and has precedence if both keys are set. ### casa-repo-prefix [:octicons-tag-24: 2.3.1](https://github.com/commercialhaskell/stack/releases/tag/v2.3.1) Deprecated in favour of [`casa`](#casa), which takes precedence if present. Default: `https://casa.fpcomplete.com` This option specifies the prefix for the URL used to pull information from the Casa server. ### color Command line equivalent (takes precedence): `--color` option This option specifies when to use color in output. The option is used as `color: `, where `` is 'always', 'never', or 'auto'. On Windows versions before Windows 10, for terminals that do not support color codes, the default is 'never'; color may work on terminals that support color codes. (The British English spelling (colour) is also accepted. In yaml configuration files, the American spelling is the alternative that has priority.) ### compiler [:octicons-tag-24: 0.1.8.0](https://github.com/commercialhaskell/stack/releases/tag/v0.1.8.0) Command line equivalent (takes precedence): `--compiler` option Overrides the compiler version in the resolver. Note that the `compiler-check` flag also applies to the version numbers. This uses the same syntax as compiler resolvers like `ghc-9.6.2`. This can be used to override the compiler for a Stackage snapshot, like this: ~~~yaml resolver: lts-21.13 compiler: ghc-9.6.2 compiler-check: match-exact ~~~ #### Building GHC from source :octicons-beaker-24: Experimental [:octicons-tag-24: 2.1.1](https://github.com/commercialhaskell/stack/releases/tag/v2.1.1) Stack supports building the GHC compiler from source, using [Hadrian](https://gitlab.haskell.org/ghc/ghc/blob/master/hadrian/README.md) (the build system for GHC). The GHC version to build and to use is defined by a a Git commit ID and a Hadrian "flavour", with the following syntax: ~~~yaml compiler: ghc-git-- ~~~ In the following example the commit ID is "5be7ad..." and the flavour is "quick": ~~~yaml compiler: ghc-git-5be7ad7861c8d39f60b7101fd8d8e816ff50353a-quick ~~~ By default, the code is retrieved from the main GHC repository. If you want to select another repository, use the `compiler-repository` option: ~~~yaml compiler-repository: git://my/ghc/repository # default # compiler-repository: https://gitlab.haskell.org/ghc/ghc.git ~~~ Stack does not check the compiler version when it uses a compiler built from source. It is assumed that the built compiler is recent enough as Stack doesn't enable any known workaround to make older compilers work. Building the compiler can take a very long time (more than one hour). For faster build times, use Hadrian flavours that disable documentation generation. #### Bootstrap compiler Building GHC from source requires a working GHC (known as the bootstrap compiler). As we use a Stack based version of Hadrian (`hadrian/build-stack` in GHC sources), the bootstrap compiler is configured into `hadrian/stack.yaml` and fully managed by Stack. !!! note For some commit IDs, the resolver specified in `hadrian/stack.yaml` specifies a version of GHC that cannot be used to build GHC. This results in GHC's `configure` script reporting messages similar to the following before aborting: ~~~text checking version of ghc... 9.0.2 configure: error: GHC version 9.2 or later is required to compile GHC. ~~~ The resolution is: (1) to specify an alternative resolver (one that specifies a sufficiently recent version of GHC) on the command line, using Stack's option `--resolver `. Stack will use that resolver when running GHC's `configure` script; and (2) to set the contents of the `STACK` environment variable to be `stack --resolver `. Hadrian's `build-stack` script wil refer to that environment variable for the Stack command it uses. #### Hadrian prerequisites The Hadrian build system has certain [prerequisites](https://gitlab.haskell.org/ghc/ghc/-/wikis/building/preparation). It requires certain versions of the `happy` and `alex` executables on the PATH. Stack will build and install `happy` and `alex`, if not already on the PATH. === "macOS" Hadrian requires, or case use, certain tools or Python packages that do not come with macOS by default and that need to be installed using `brew` or `pip3` (Python). Hadrian's LaTeX documentation also requires the [DejaVu fonts](https://dejavu-fonts.github.io/) to be installed. ~~~zsh brew install python@3.11 # GHC uses a Python script named `boot`. brew install automake # Tool for generating GNU Standards-compliant Makefiles. brew install texinfo # Official documentation format of the GNU project. pip3 install -U sphinx # Sphinx is the Python documentation generator. brew install --cask mactex # MacTeX: Full TeX Live distribution with GUI applications ~~~ === "Windows" Hadrian requires, or can use, certain MSYS2 or Python packages that do not come with the Stack-supplied MSYS2 by default and need to be installed using `pacman` (MSYS2) or `pip` (Python). Hadrian's LaTeX documentation also requires the [DejaVu fonts](https://dejavu-fonts.github.io/) to be installed. ~~~pwsh stack exec -- pacman --sync --refresh # Synchronize MSYS2 package databases stack exec -- pacman --sync mingw-w64-x86_64-python-pip # The PyPA recommended tool (pip) for installing Python packages. Also # installs Python as a dependency. GHC uses a Python script named `boot`. # The package must be the one from the `mingw64` MSYS2 repository, as Python # from the `msys` repository cannot interpret Windows file paths correctly. stack exec -- pacman --sync mingw-w64-x86_64-autotools # The GNU autotools build system, including `autoreconf`, `aclocal` # and `make`. GHC uses a sh script named `configure` which is itself created # from a file named `configure.ac`. stack exec -- pacman --sync patch # A utility to apply patch files to original sources. stack exec -- pacman --sync texinfo # Utilities to work with and produce manuals, ASCII text, and on-line # documentation from a single source file, including `makeinfo`. stack exec -- pacman --sync mingw-w64-x86_64-ca-certificates # Common CA (certificate authority) certificates. stack exec -- pip install -U sphinx # Sphinx is the Python documentation generator. ~~~ Hadrian may require certain LaTeX packages and may prompt for these to be installed duing the build process. #### Global packages The GHC compiler you build from sources may depend on unreleased versions of some global packages (e.g. Cabal). It may be an issue if a package you try to build with this compiler depends on such global packages because Stack may not be able to find versions of those packages (on Hackage, etc.) that are compatible with the compiler. The easiest way to deal with this issue is to drop the offending packages as follows. Instead of using the packages specified in the resolver, the global packages bundled with GHC will be used. ~~~yaml drop-packages: - Cabal - ... ~~~ Another way to deal with this issue is to add the relevant packages as `extra-deps` built from source. To avoid mismatching versions, you can use exactly the same commit id you used to build GHC as follows: ~~~ extra-deps: - git: https://gitlab.haskell.org/ghc/ghc.git commit: 5be7ad7861c8d39f60b7101fd8d8e816ff50353a subdirs: - libraries/Cabal/Cabal - libraries/... ~~~ ### compiler-check [:octicons-tag-24: 0.1.4.0](https://github.com/commercialhaskell/stack/releases/tag/v0.1.4.0) Default: `match-minor` Specifies how the compiler version in the resolver is matched against concrete versions. Valid values: * `match-minor`: make sure that the first three components match, but allow patch-level differences. For example< 7.8.4.1 and 7.8.4.2 would both match 7.8.4. This is useful to allow for custom patch levels of a compiler. * `match-exact`: the entire version number must match precisely * `newer-minor`: the third component can be increased, e.g. if your resolver is `ghc-7.10.1`, then 7.10.2 will also be allowed. This was the default up through Stack 0.1.3 ### concurrent-tests [:octicons-tag-24: 0.1.2.0](https://github.com/commercialhaskell/stack/releases/tag/v0.1.2.0) Default: `true` This option specifies whether test suites should be executed concurrently with each other. The default is `true` since this is usually fine and it often means that tests can complete earlier. However, if some test suites require exclusive access to some resource, or require a great deal of CPU or memory resources, then it makes sense to set this to `false`. ~~~yaml concurrent-tests: false ~~~ ### configure-options [:octicons-tag-24: 2.1.1](https://github.com/commercialhaskell/stack/releases/tag/v2.1.1) Related command line (takes precedence): [`stack build --PROG-option`](build_command.md#prog-option-options) options `configure-options` can specify Cabal (the library) options (including `--PROG-option` or `--PROG-options` options) for the configure step of the Cabal build process for a named package, all local packages that are targets (using the `$targets` key), all local packages (targets or otherwise) (using the `$locals` key), or all packages (local or otherwise) (using the `$everything` key). ~~~yaml configure-options: $everything: - --with-gcc - /some/path $locals: - --happy-option=--ghc my-package: - --another-flag ~~~ ### connection-count Default: `8` Integer indicating how many simultaneous downloads are allowed to happen. ### default-template Default: `new-template` in the [stack-templates](https://github.com/commercialhaskell/stack-templates/) repository. This option specifies which template to use with `stack new`, when none is specified. Other templates are listed in the [stack-templates](https://github.com/commercialhaskell/stack-templates/) repository. See the output of `stack templates`. ### docker Command line equivalents: `--docker-*` flags and options (see `stack --docker-help` for details). For further information, see the [Docker integration](docker_integration.md#configuration) documentation. ### dump-logs [:octicons-tag-24: 1.3.0](https://github.com/commercialhaskell/stack/releases/tag/v1.3.0) Default: `warning` Command line equivalent (takes precedence): `--[no-]dump-logs` flag In the case of *non-interleaved* output and *more than one* target package, Stack sends the build output from GHC for each target package to a log file, unless an error occurs that prevents that. For further information, see the [`stack build --[no-]interleaved-output` flag](build_command.md#-no-interleaved-output-flag) documentation. The value of the `dump-logs` key controls what, if any, log file content is sent ('dumped') to the standard error stream of the console at the end of the build. Possible values are: ~~~yaml dump-logs: none # don't dump the content of any log files dump-logs: warning # dump the content of any log files that include GHC warnings dump-logs: all # dump the content of all log files ~~~ At the command line, `--no-dump-logs` is equivalent to `dump-logs: none` and `--dump-logs` is equivalent to `dump-logs: all`. If GHC reports an error during the build and a log file is created, that build output will be included in the log file. Stack will also report errors during building to the standard error stream. That stream can be piped to a file. For example, for a file named `stderr.log`: ~~~text stack --no-dump-logs --color always build --no-interleaved-output 2> stderr.log ~~~ ### extra-include-dirs Default: `[]` Command line equivalent: `--extra-include-dirs` option (repeat for each directory) A list of extra paths to be searched for header files. Paths should be absolute ~~~yaml extra-include-dirs: - /opt/foo/include ~~~ Since these are system-dependent absolute paths, it is recommended that you specify these in your `config.yaml` file. If you control the build environment in your project's ``stack.yaml``, perhaps through docker or other means, then it may well make sense to include these there as well. ### extra-lib-dirs Default: `[]` Command line equivalent: `--extra-lib-dirs` option (repeat for each directory) A list of extra paths to be searched for libraries. Paths should be absolute ~~~yaml extra-lib-dirs: - /opt/foo/lib ~~~ Since these are system-dependent absolute paths, it is recommended that you specify these in your `config.yaml` file. If you control the build environment in your project's ``stack.yaml``, perhaps through Docker or other means, then it may well make sense to include these there as well. ### extra-path [:octicons-tag-24: 0.1.4.0](https://github.com/commercialhaskell/stack/releases/tag/v0.1.4.0) This option specifies additional directories to prepend to the PATH. These will be used when resolving the location of executables, and will also be visible in the PATH of processes run by Stack. For example, to prepend `/path-to-some-dep/bin` to your PATH: ~~~yaml extra-path: - /path-to-some-dep/bin ~~~ Other paths added by Stack - things like the project's binary directory and the compiler's binary directory - will take precedence over those specified here (the automatic paths get prepended). ### ghc-build [:octicons-tag-24: 1.3.0](https://github.com/commercialhaskell/stack/releases/tag/v1.3.0) Default: `standard` Command line equivalent (takes precedence): `--ghc-build` option Stack identifies different GHC executables by platform (operating system and machine architecture), (optional) GHC variant and (optional) GHC build. See [`setup-info`](#setup-info). `ghc-build` specifies a specialized architecture for the GHC executable. Normally this is determined automatically, but it can be overridden. Possible arguments include `standard`, `gmp4`, `nopie`, `tinfo6`, `tinfo6-libc6-pre232`, `tinfo6-nopie`, `ncurses6`, `int-native` and `integersimple`. ### ghc-options [:octicons-tag-24: 0.1.4.0](https://github.com/commercialhaskell/stack/releases/tag/v0.1.4.0) Default: `{}` Related command line (takes precedence): [`stack build --ghc-options`](build_command.md#ghc-options-option) option `ghc-options` can specify GHC command line options for a named package, all local packages that are targets (using the `$targets` key), all local packages (targets or otherwise) (using the `$locals` key), or all packages (local or otherwise) (using the `$everything` key). ~~~yaml ghc-options: "$everything": -O2 "$locals": -Wall "$targets": -Werror some-package: -DSOME_CPP_FLAG ~~~ GHC's command line options are _order-dependent_ and evaluated from left to right. Later options can override earlier options. Stack applies options (as applicable) in the order of `$everything`, `$locals`, `$targets`, and then those for the named package. Any existing GHC command line options of a package are applied after those specified in Stack's YAML configuration. Since Stack 1.6.1, setting a GHC options for a specific package will automatically promote it to a local package (much like setting a custom package flag). However, setting options via `$everything` on all flags will not do so (see [GitHub discussion](https://github.com/commercialhaskell/stack/issues/849#issuecomment-320892095) for reasoning). This can lead to unpredictable behavior by affecting your snapshot packages. !!! note Before Stack 1.6.1, the key `*` (then deprecated) had the same function as the key `$everything`. ### ghc-variant [:octicons-tag-24: 0.1.5.0](https://github.com/commercialhaskell/stack/releases/tag/v0.1.5.0) Default: `standard` Command line equivalent (takes precedence): `--ghc-variant` option Stack identifies different GHC executables by platform (operating system and machine architecture), (optional) GHC variant and (optional) GHC build. See [`setup-info`](#setup-info). `ghc-variant` specifies a variant of the GHC executable. Known values are: * `standard`: Use the standard GHC binary distribution * `int-native`: From GHC 9.4.1, use a GHC bindist that uses the Haskell-native big-integer [backend](https://downloads.haskell.org/~ghc/9.0.2/docs/html/users_guide/9.0.1-notes.html#highlights). For further information, see this [article](https://iohk.io/en/blog/posts/2020/07/28/improving-haskells-big-numbers-support/). * `integersimple`: Use a GHC bindist that uses [integer-simple instead of GMP](https://ghc.haskell.org/trac/ghc/wiki/ReplacingGMPNotes) * any other value: Use a custom GHC bindist. You should specify [setup-info](#setup-info) or [setup-info-locations](#setup-info-locations) so `stack setup` knows where to download it, or pass the `stack setup --ghc-bindist` argument on the command-line This option is incompatible with `system-ghc: true`. ### hackage-base-url [:octicons-tag-24: 1.9.1](https://github.com/commercialhaskell/stack/releases/tag/v1.9.1) Default: `https://hackage.haskell.org/` Sets the address of the Hackage server to upload the package to. ~~~yaml hackage-base-url: https://hackage.example.com/ ~~~ ### hide-source-paths Default: `true` ([:octicons-tag-24: 2.1.1](https://github.com/commercialhaskell/stack/releases/tag/v2.1.1)) Whether to use the `-fhide-source-paths` option by default for GHC >= 8.2: ~~~yaml hide-source-paths: false ~~~ Build output when enabled: ~~~text ... [1 of 2] Compiling Lib [2 of 2] Compiling Paths_test_pr ... ~~~ Build output when disabled: ~~~text ... [1 of 2] Compiling Lib ( src/Lib.hs, .stack-work/dist/x86_64-linux-tinfo6/Cabal-2.4.0.1/build/Lib.o ) ... ~~~ ### hide-th-loading Default: `true` Strip out the "Loading ..." lines from GHC build output, produced when using Template Haskell. ### ignore-revision-mismatch (Removed 1.11) This flag was introduced in Stack 1.6, and removed on the move to Pantry. You will receive a warning if this configuration value is set. ### install-ghc Default: `true` ([:octicons-tag-24: 1.5.0](https://github.com/commercialhaskell/stack/releases/tag/v1.5.0)) Command line equivalent (takes precedence): `--[no-]install-ghc` flag Whether or not to automatically install GHC when necessary. ### jobs Default: the number of CPUs (cores) that the machine has. Command line equivalent (takes precedence): [`-j`, `--jobs` option](global_flags.md#-jobs-or-j-option) Specifies the number of concurrent jobs (principally, Stack actions during building - see further below) to run. When [building GHC from source](#building-ghc-from-source), specifies the `-j[]` flag of GHC's Hadrian build system. In some circumstances, the default can cause some machines to run out of memory during building. If those circumstances arise, specify `jobs: 1`. This configuration option is distinct from GHC's own `-j[]` flag, which relates to parallel compilation of modules within a package. ### local-bin-path Default (on Unix-like operating systems): `~/.local/bin` Default (on Windows): `%APPDATA%\local\bin` Command line equivalent (takes precedence): `--local-bin-path` option Specifies the target directory for [`stack build --copy-bins`](build_command.md#-no-copy-bins-flag) and `stack install`. An absolute or relative path can be specified. If the project-level configuration is provided in the `global-project` directory in the [Stack root](stack_root.md), a relative path is assumed to be relative to the current directory. Otherwise, it is assumed to be relative to the directory of the project-level configuration file. ### local-programs-path [:octicons-tag-24: 1.3.0](https://github.com/commercialhaskell/stack/releases/tag/v1.3.0) This overrides the location of the Stack 'programs' directory, where tools like GHC get installed. The path must be an absolute one. Stack's defaults differ between Unix-like operating systems and Windows. === "Unix-like" Default: `programs` directory in the [Stack root](stack_root.md). === "Windows" Default: `%LOCALAPPDATA%\Programs\stack`, if the `%LOCALAPPDATA%` environment variable exists. Otherwise, the `programs` directory in the [Stack root](stack_root.md). The MSYS2 tool is also installed in the Stack 'programs' directory. !!! warning If there is a space character in the path to Stack's 'programs' directory this may cause problems with building packages that make use of the GNU project's `autoconf` package and `configure` shell script files. That may be the case particularly if there is no corresponding short name ('8 dot 3' name) for the directory in the path with the space (which may be the case if '8 dot 3' names have been stripped or their creation not enabled by default). If there are problems building, it will be necessary to specify an alternative path that does not contain space characters. Examples of packages on Hackage that make use of `configure` are `network` and `process`. ### modify-code-page [:octicons-tag-24: 0.1.6.0](https://github.com/commercialhaskell/stack/releases/tag/v0.1.6.0) Restrictions: Windows systems only. Default: `true` Command line equivalent (takes precedence): `--[no-]modify-code-page` flag Whether to modify the code page for UTF-8 output. ~~~yaml modify-code-page: false ~~~ ### nix [:octicons-tag-24: 0.1.10.0](https://github.com/commercialhaskell/stack/releases/tag/v0.1.10.0) Default: ~~~yaml nix: enable: false # Except on NixOS, where `enable: true` pure: true packages: [] shell-file: nix-shell-options: [] path: [] add-gc-roots: false ~~~ Command line equivalents: `--nix-*` flags and options (see `stack --nix-help` for details). For further information, see the [Nix integration](nix_integration.md#configuration) documentation. ### notify-if-nix-on-path :octicons-tag-24: UNRELEASED Default: `true` If Stack's integration with the Nix package manager is not enabled, should Stack notify the user if a `nix` executable is on the PATH? ### package-index [:octicons-tag-24: 2.9.3](https://github.com/commercialhaskell/stack/releases/tag/v2.9.3) Default: ~~~yaml package-index: download-prefix: https://hackage.haskell.org/ hackage-security: keyids: - 0a5c7ea47cd1b15f01f5f51a33adda7e655bc0f0b0615baa8e271f4c3351e21d - 1ea9ba32c526d1cc91ab5e5bd364ec5e9e8cb67179a471872f6e26f0ae773d42 - 2c6c3627bd6c982990239487f1abd02e08a02e6cf16edb105a8012d444d870c3 - 51f0161b906011b52c6613376b1ae937670da69322113a246a09f807c62f6921 - fe331502606802feac15e514d9b9ea83fee8b6ffef71335479a2e68d84adc6b0 key-threshold: 3 ignore-expiry: true ~~~ Takes precedence over the `package-indices` key, which is deprecated. Specify the package index. The index must use the [Hackage Security](https://hackage.haskell.org/package/hackage-security) format. This setting is most useful for providing a mirror of the official Hackage server for * bypassing a firewall; or * faster downloads. If the setting specifies an index that does not mirror Hackage, it is likely that will result in significant breakage, including most snapshots failing to work. In the case of Hackage, the keys of its root key holders are contained in the `haskell-infra/hackage-root-keys` [repository](https://github.com/haskell-infra/hackage-root-keys). The Hackage package index is signed. A signature is valid when three key holders have signed. The Hackage timestamp is also signed. A signature is valid when one key holder has signed. If the `hackage-security` key is absent, the Hackage Security configuration will default to that for the official Hackage server. `key-threshold` specifies the minimum number of keyholders that must have signed the package index for it to be considered valid. `ignore-expiry` specifies whether or not the expiration of timestamps should be ignored. ### package-indices [:octicons-tag-24: 2.1.1](https://github.com/commercialhaskell/stack/releases/tag/v2.1.1) Deprecated in favour of [`package-index`](#package-index), which takes precedence if present. Default: ~~~yaml package-indices: - download-prefix: https://hackage.haskell.org/ hackage-security: keyids: - 0a5c7ea47cd1b15f01f5f51a33adda7e655bc0f0b0615baa8e271f4c3351e21d - 1ea9ba32c526d1cc91ab5e5bd364ec5e9e8cb67179a471872f6e26f0ae773d42 - 2c6c3627bd6c982990239487f1abd02e08a02e6cf16edb105a8012d444d870c3 - 51f0161b906011b52c6613376b1ae937670da69322113a246a09f807c62f6921 - fe331502606802feac15e514d9b9ea83fee8b6ffef71335479a2e68d84adc6b0 key-threshold: 3 ignore-expiry: true ~~~ !!! note Before Stack 2.1.3, the default for `ignore-expiry` was `false`. For more information, see [issue #4928](https://github.com/commercialhaskell/stack/issues/4928). !!! note Before Stack 2.1.1, Stack had a different approach to `package-indices`. For more information, see [issue #4137](https://github.com/commercialhaskell/stack/issues/4137). Specify the package index. For further information, see the `package-index` [documentation](#package-index). ### pvp-bounds [:octicons-tag-24: 0.1.5.0](https://github.com/commercialhaskell/stack/releases/tag/v0.1.5.0) Default: `none` Command line equivalent (takes precedence): `stack sdist --pvp-bounds` option or `stack upload --pvp-bounds` option !!! warning As of Stack 1.6.0, this feature does not reliably work, due to issues with the Cabal library's printer. Stack will generate a warning when a lossy conversion occurs, in which case you may need to disable this setting. For further information, see issue [#3550](https://github.com/commercialhaskell/stack/issues/3550). When using the `sdist` and `upload` commands, this setting determines whether the Cabal file's dependencies should be modified to reflect PVP lower and upper bounds. #### Basic use Values are `none` (unchanged), `upper` (add upper bounds), `lower` (add lower bounds), and both (and upper and lower bounds). The algorithm Stack follows is: * If an upper or lower bound (other than `>= 0` - 'any version') already exists on a dependency, it is left alone * When adding a lower bound, Stack looks at the current version specified by `stack.yaml`, and sets it as the lower bound (e.g., `foo >= 1.2.3`) * When adding an upper bound, Stack sets it as less than the next major version (e.g., `foo < 1.3`) ~~~yaml pvp-bounds: none ~~~ For further information, see the announcement [blog post](https://www.fpcomplete.com/blog/2015/09/stack-pvp). #### Use with Cabal file revisions [:octicons-tag-24: 1.5.0](https://github.com/commercialhaskell/stack/releases/tag/v1.5.0) Each of the values listed above supports adding `-revision` to the end of the value, e.g. `pvp-bounds: both-revision`. This means that, when uploading to Hackage, Stack will first upload your tarball with an unmodified Cabal file, and then upload a Cabal file revision with the PVP bounds added. This can be useful - especially combined with the [Stackage no-revisions feature](http://www.snoyman.com/blog/2017/04/stackages-no-revisions-field) - as a method to ensure PVP compliance without having to proactively fix bounds issues for Stackage maintenance. ### recommend-stack-upgrade [:octicons-tag-24: 2.1.1](https://github.com/commercialhaskell/stack/releases/tag/v2.1.1) Default: `true` When Stack notices that a new version of Stack is available, should it notify the user? ### rebuild-ghc-options [:octicons-tag-24: 0.1.6.0](https://github.com/commercialhaskell/stack/releases/tag/v0.1.6.0) Default: `false` Should Stack rebuild a package when its GHC options change? The default value reflects that, in most cases, GHC options are used to affect optimization levels and warning behavior, for which GHC does not recompile the modules. !!! note Before Stack 0.1.6.0, Stack rebuilt a package when its GHC options changed. ### require-stack-version Default: `"-any"` Require a version of Stack within the specified range ([cabal-style](https://www.haskell.org/cabal/users-guide/developing-packages.html#build-information)) to be used for this project. Example: `require-stack-version: "== 0.1.*"` ### save-hackage-creds [:octicons-tag-24: 1.5.0](https://github.com/commercialhaskell/stack/releases/tag/v1.5.0) Default: `true` Controls whether, when using `stack upload`, the user's Hackage username and password are stored in a local file. ~~~yaml save-hackage-creds: true ~~~ ### setup-info [:octicons-tag-24: 0.1.5.0](https://github.com/commercialhaskell/stack/releases/tag/v0.1.5.0) The `setup-info` dictionary specifies download locations for tools to be installed during set-up, such as GHC or, on Windows, 7z and MSYS2. The dictionary maps `('Tool', 'Platform', 'Version')` to the location where it can be obtained. For example, mapping `(GHC, 64-bit Windows, 9.2.3)` to the URL hosting the archive file for GHC's installation. Possible usages of this configuration option are: 1. Using Stack offline or behind a firewall. 2. Extending the tools known to Stack, such as cutting-edge versions of GHC or builds for custom Linux distributions (for use with the [ghc-variant](#ghc-variant) option). By default, Stack obtains the dictionary from [stack-setup-2.yaml](https://github.com/commercialhaskell/stackage-content/raw/master/stack/stack-setup-2.yaml). The `setup-info` dictionary is constructed in the following order: 1. `setup-info` in the YAML configuration - inline configuration 2. `--setup-info-yaml` command line arguments - URLs or paths. Multiple locations may be specified. 3. `setup-info-locations` in the YAML configuration - URLs or paths. See further below. The format of this key is the same as in the default [stack-setup-2.yaml](https://github.com/commercialhaskell/stackage-content/raw/master/stack/stack-setup-2.yaml). For example, GHC 9.2.3 of custom variant `myvariant` (see further below) on 64-bit Windows: ~~~yaml setup-info: ghc: windows64-custom-myvariant: 9.2.3: url: "https://example.com/ghc-9.2.3-x86_64-unknown-mingw32-myvariant.tar.xz" ~~~ 'Platforms' are pairs of an operating system and a machine architecture (for example, 32-bit i386 or 64-bit x86-64) (represented by the `Cabal.Distribution.Systems.Platform` type). Stack currently (version 2.13.1) supports the following pairs in the format of the `setup-info` key: |Operating system|I386 arch|X86_64 arch|Other machine architectures | |----------------|---------|-----------|------------------------------------------------------------| |Linux |linux32 |linux64 |AArch64: linux-aarch64, Arm: linux-armv7, Sparc: linux-sparc| |OSX |macosx |macosx | | |Windows |windows32|windows64 | | |FreeBSD |freebsd32|freebsd64 |AArch64: freebsd-aarch64 | |OpenBSD |openbsd32|openbsd64 | | For GHC, the distinguishing 'Version' in the key format includes a 'tag' for any (optional) GHC variant (see [ghc-variant](#ghc-variant)) and a further 'tag' for any (optional) specialised GHC build (see [ghc-build](#ghc-build)). The optional variant 'tag' is either `-integersimple` or `-custom-`. For example, for GHC 9.0.2 of specialised GHC build `tinfo6` on x86_64 Linux: ~~~yaml setup-info: ghc: linux64-tinfo6: 9.0.2: url: "http://downloads.haskell.org/~ghc/9.0.2/ghc-9.0.2a-x86_64-fedora27-linux.tar.xz" content-length: 237286244 sha1: affc2aaa3e6a1c446698a884f56a0a13e57f00b4 sha256: b2670e9f278e10355b0475c2cc3b8842490f1bca3c70c306f104aa60caff37b0 ~~~ On Windows, the required 7z executable and DLL tools are represented in the format of the `setup-info` key simply by `sevenzexe-info` and `sevenzdll-info`. This configuration **adds** the specified setup information metadata to the default. Specifying this configuration **does not** prevent the default [stack-setup-2.yaml](https://github.com/commercialhaskell/stackage-content/raw/master/stack/stack-setup-2.yaml) from being consulted as a fallback. If, however, you need to **replace** the default `setup-info` dictionary, use the following: ~~~yaml setup-info-locations: [] ~~~ ### setup-info-locations [:octicons-tag-24: 2.3.1](https://github.com/commercialhaskell/stack/releases/tag/v2.3.1) Command line equivalent (takes precedence): `--setup-info-yaml` option By way of introduction, see the [`setup-info`](#setup-info) option. This option specifies the location(s) of `setup-info` dictionaries. The first location which provides a dictionary that specifies the location of a tool - `('Tool', 'Platform', 'Version')` - takes precedence. For example, you can extend the default tools, with a fallback to the default `setup-info` location, as follows: ~~~yaml setup-info-locations: - C:/stack-offline/my-stack-setup.yaml - relative/inside/my/project/setup-info.yaml - \\smbShare\stack\my-stack-setup.yaml - http://stack-mirror.com/stack-setup.yaml # Fallback to the default location - https://github.com/commercialhaskell/stackage-content/raw/master/stack/stack-setup-2.yaml ~~~ Stack only refers to the default `setup-info` location if no locations are specified in the `setup-info-locations` configuration or on the command line using the `--setup-info-yaml` option. For example, both of the following will cause `stack setup` not to consult the default `setup-info` location: ~~~yaml setup-info-locations: - C:/stack-offline/my-stack-setup.yaml ~~~ and ~~~yaml setup-info-locations: [] ~~~ Relative paths are resolved relative to the `stack.yaml` file (either the one in the local project or the global `stack.yaml`). Relative paths may also be used for the installation paths to tools (such as GHC or 7z). This allows vendoring the tools inside a monorepo (a single repository storing many projects). For example: Directory structure: ~~~text - src/ - installs/ - my-stack-setup.yaml - 7z.exe - 7z.dll - ghc-9.2.3.tar.xz - stack.yaml ~~~ In the project's `stack.yaml`: ~~~yaml setup-info-locations: - installs/my-stack-setup.yaml ~~~ In `installs/my-stack-setup.yaml`: ~~~yaml sevenzexe-info: url: "installs/7z.exe" sevenzdll-info: url: "installs/7z.dll" ghc: windows64: 9.2.3: url: "installs/ghc-9.2.3.tar.xz" ~~~ ### skip-ghc-check Default: `false` Command line equivalent (takes precedence): `--[no-]skip-ghc-check` flag Should we skip the check to confirm that your system GHC version (on the PATH) matches what your project expects? ### skip-msys [:octicons-tag-24: 0.1.2.0](https://github.com/commercialhaskell/stack/releases/tag/v0.1.2.0) Restrictions: Windows systems only Default: `false` Command line equivalent (takes precedence): `--[no-]skip-msys` flag Skips checking for and installing MSYS2 when stack is Setting up the environment. This usually doesn't make sense in project-level configurations, just in `config.yaml`. ~~~yaml skip-msys: true ~~~ ### snapshot-location-base [:octicons-tag-24: 2.5.1](https://github.com/commercialhaskell/stack/releases/tag/v2.5.1) Default: https://raw.githubusercontent.com/commercialhaskell/stackage-snapshots/master/ (as set in the `pantry` library) Command line equivalent (takes precedence): `--snapshot-location-base` option Sets the base location of the LTS Haskell or Stackage Nightly snapshots. For example: ~~~yaml snapshot-location-base: https://example.com/snapshots/location/ ~~~ has the following effect: * `lts-X.Y` expands to `https://example.com/snapshots/location/lts/X/Y.yaml` * `nightly-YYYY-MM-DD` expands to `https://example.com/snapshots/location/nightly/YYYY/M/D.yaml` This key is convenient in setups that restrict access to GitHub, for instance closed corporate setups. In this setting, it is common for the development environment to have general access to the internet, but not for testing/building environments. To avoid the firewall, one can run a local snapshots mirror and then use a custom `snapshot-location-base` in the closed environments only. ### stack-colors Command line equivalent (takes precedence): `--stack-colors` option Stack uses styles to format some of its output. The default styles do not work well with every terminal theme. This option specifies Stack's output styles, allowing new styles to replace the defaults. The option is used as `stack-colors: `, where `` is a colon-delimited sequence of key=value, 'key' is a style name and 'value' is a semicolon-delimited list of 'ANSI' SGR (Select Graphic Rendition) control codes (in decimal). Use the command `stack ls stack-colors --basic` to see the current sequence. The 'ANSI' standards refer to (1) standard ECMA-48 'Control Functions for Coded Character Sets' (5th edition, 1991); (2) extensions in ITU-T Recommendation (previously CCITT Recommendation) T.416 (03/93) 'Information Technology – Open Document Architecture (ODA) and Interchange Format: Character Content Architectures' (also published as ISO/IEC International Standard 8613-6); and (3) further extensions used by 'XTerm', a terminal emulator for the X Window System. The 'ANSI' SGR codes are described in a [Wikipedia article](http://en.wikipedia.org/wiki/ANSI_escape_code) and those codes supported on current versions of Windows in [Microsoft's documentation](https://docs.microsoft.com/en-us/windows/console/console-virtual-terminal-sequences). For example, users of the popular [Solarized Dark](https://ethanschoonover.com/solarized/) terminal theme might wish to set the styles as follows: ~~~yaml stack-colors: error=31:good=32:shell=35:dir=34:recommendation=32:target=95:module=35:package-component=95:secondary=92:highlight=32 ~~~ In respect of styles used in verbose output, some of that output occurs before the configuration file is processed. (The British English spelling (colour) is also accepted. In YAML configuration files, the American spelling is the alternative that has priority.) ### stack-developer-mode [:octicons-tag-24: 2.3.3](https://github.com/commercialhaskell/stack/releases/tag/v2.3.3) Default (official distributed binaries): `false` Default (built from source): `true` Turns on a mode where some messages are printed at WARN level instead of DEBUG level, especially useful for developers of Stack itself. ~~~yaml stack-developer-mode: false ~~~ ### system-ghc Default: `false`, unless the [Docker](docker_integration.md) or [Nix](nix_integration.md) integration is enabled. Command line equivalent (takes precedence): `--[no-]system-ghc` flag Enables or disables using the GHC available on the PATH. (Make sure PATH is explicit, i.e., don't use ~.) Useful to enable if you want to save the time, bandwidth or storage space needed to setup an isolated GHC. In a Nix-enabled configuration, Stack is incompatible with `system-ghc: false`. ~~~yaml # Turn on system GHC system-ghc: true ~~~ ### templates Command line equivalent (takes precedence): `stack new --param :` (or `-p`) option Templates used with `stack new` have a number of parameters that affect the generated code. These can be set for all new projects you create. The result of them can be observed in the generated LICENSE and Cabal files. The value for all of these parameters must be strings. The parameters are: `author-email`, `author-name`, `category`, `copyright`, `year` and `github-username`. * _author-email_ - sets the `maintainer` property in Cabal * _author-name_ - sets the `author` property in Cabal and the name used in LICENSE * _category_ - sets the `category` property in Cabal. This is used in Hackage. For examples of categories see [Packages by category](https://hackage.haskell.org/packages/). It makes sense for `category` to be set on a per project basis because it is uncommon for all projects a user creates to belong to the same category. The category can be set per project by passing `-p "category:value"` to the `stack new` command. * _copyright_ - sets the `copyright` property in Cabal. It is typically the name of the holder of the copyright on the package and the year(s) from which copyright is claimed. For example: `Copyright (c) 2006-2007 Joe Bloggs` * _year_ - if `copyright` is not specified, `year` and `author-name` are used to generate the copyright property in Cabal. If `year` is not specified, it defaults to the current year. * _github-username_ - used to generate `homepage` and `source-repository` in Cabal. For instance `github-username: myusername` and `stack new my-project new-template` would result: ~~~yaml homepage: http://github.com/myusername/my-project#readme source-repository head type: git location: https://github.com/myusername/my-project ~~~ These properties can be set in `config.yaml` as follows: ~~~yaml templates: params: author-name: Your Name author-email: youremail@example.com category: Your Projects Category copyright: 'Copyright (c) 2023 Your Name' github-username: yourusername ~~~ Additionally, `stack new` can automatically initialize source control repositories in the directories it creates. Source control tools can be specified with the `scm-init` option. At the moment, only `git` is supported. ~~~yaml templates: scm-init: git ~~~ ### urls Default: ~~~yaml urls: latest-snapshot: https://www.stackage.org/download/snapshots.json ~~~ Customize the URLs where Stack looks for snapshot build plans. ### with-gcc Command line equivalent (takes precedence): `--with-gcc` option Specify a path to GCC explicitly, rather than relying on the normal path resolution. ~~~yaml with-gcc: /usr/local/bin/gcc-5 ~~~ ### with-hpack Command line equivalent (takes precedence): `--with-hpack` option Use an [Hpack](https://github.com/sol/hpack) executable, rather than Stack's in-built version of the Hpack functionality. ~~~yaml with-hpack: /usr/local/bin/hpack ~~~ ### work-dir [:octicons-tag-24: 0.1.10.0](https://github.com/commercialhaskell/stack/releases/tag/v0.1.10.0) Default: `.stack-work` Command line equivalent (takes precedence): [`--work-dir`](global_flags.md#-work-dir-option) option Environment variable alternative (lowest precedence): [`STACK_WORK`](environment_variables.md#stack_work) `work-dir` specifies the path of Stack's work directory, within a local project or package directory. The path must be a relative one, relative to the root directory of the project or package. The relative path cannot include a `..` (parent directory) component. ## Customisation scripts ### GHC installation customisation [:octicons-tag-24: 2.9.1](https://github.com/commercialhaskell/stack/releases/tag/v2.9.1) On Unix-like operating systems and Windows, Stack's installation procedure can be fully customised by placing a `sh` shell script (a 'hook') in the [Stack root](stack_root.md) directory at `hooks/ghc-install.sh`. On Unix-like operating systems, the script file must be made executable. The script is run by the `sh` application (which is provided by MSYS2 on Windows). The script **must** return an exit code of `0` and the standard output **must** be the absolute path to the GHC binary that was installed. Otherwise Stack will ignore the script and possibly fall back to its own installation procedure. The script is not run when `system-ghc: true`. When `install-ghc: false`, the script is still run, which allows you to ensure that only your script will install GHC and Stack won't default to its own installation logic, even when the script fails. The following environment variables are always available to the script: * `HOOK_GHC_TYPE = "bindist" | "git" | "ghcjs"` For "bindist", additional variables are: * `HOOK_GHC_VERSION = ` For "git", additional variables are: * `HOOK_GHC_COMMIT = ` * `HOOK_GHC_FLAVOR = ` For "ghcjs", additional variables are: * `HOOK_GHC_VERSION = ` * `HOOK_GHCJS_VERSION = ` An example script is: ~~~sh #!/bin/sh set -eu case $HOOK_GHC_TYPE in bindist) # install GHC here, not printing to stdout, e.g.: # command install $HOOK_GHC_VERSION >/dev/null ;; git) >&2 echo "Hook doesn't support installing from source" exit 1 ;; *) >&2 echo "Unsupported GHC installation type: $HOOK_GHC_TYPE" exit 2 ;; esac echo "location/to/ghc/executable" ~~~ If the following script is installed by GHCup, GHCup makes use of it, so that if Stack needs a version of GHC, GHCup takes over obtaining and installing that version: ~~~sh #!/bin/sh set -eu case $HOOK_GHC_TYPE in bindist) ghcdir=$(ghcup whereis --directory ghc "$HOOK_GHC_VERSION" || ghcup run --ghc "$HOOK_GHC_VERSION" --install) || exit 3 printf "%s/ghc" "${ghcdir}" ;; git) # TODO: should be somewhat possible >&2 echo "Hook doesn't support installing from source" exit 1 ;; *) >&2 echo "Unsupported GHC installation type: $HOOK_GHC_TYPE" exit 2 ;; esac ~~~