This page is intended to fully document all configuration options available in the stack.yaml file. Note that this page is likely to be both incomplete and sometimes inaccurate. If you see such cases, please update the page, and if you're not sure how, open an issue labeled "question".
The stack.yaml configuration options break down into project-specific options in:
and non-project-specific options in:
/etc/stack/config.yaml-- for system global non-project default options
~/.stack/config.yaml-- for user non-project default options
- The project file itself may also contain non-project specific options
Note: When stack is invoked outside a stack project it will source project
specific options from
~/.stack/global-project/stack.yaml. When stack is
invoked inside a stack project, only options from
<project dir>/stack.yaml are
~/.stack/global-project/stack.yaml is ignored.
Note 2: A common source of confusion is the distinction between configuration
stack.yaml file versus a cabal file. If you're trying to understand this
breakdown, see stack vs cabal config.
Project-specific options are only valid in the
stack.yaml file local to a
project, not in the user or global config files.
Note: We define project to mean a directory that contains a
stack.yamlfile, which specifies how to build a set of packages. We define package to be a package with a
.cabalfile or Hpack
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
applied to your configuration. So, if you add a package to your
it will be used even if you're using a snapshot that specifies a particular
extra-deps will shadow the version specified in the
Note: Starting with Stack 2.0,
snapshotis accepted as a synonym for
resolver. Only one of these fields is permitted, not both.
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.
- Stackage Nightly snapshot, e.g.
- No snapshot, just use packages shipped with the compiler
- For GHC this looks like
- For GHC this looks like
- Custom snapshot, via a URL or relative file path. (See pantry docs for more information.)
Each of these resolvers will also determine what constraints are placed on the compiler version. See the compiler-check option for some additional control over compiler version.
Since Stack 1.11, the resolver field corresponds to a Pantry snapshot location. See the docs on pantry for more information.
NOTE Beginning with Stack 1.11, Stack has moved over to Pantry for
managing extra-deps, and has removed some legacy syntax for specifying
packages. See some conversion notes below.
A list of packages that are part of your local project. These are
specified via paths to local directories. The paths are considered
relative to the directory containing the
stack.yaml file. For
example, if your
stack.yaml is located at
packages: - hello - there/world
Your configuration means "I have packages in
If these packages should be treated as dependencies instead, specify
extra-deps, described below.
packages field is optional. If omitted, it is treated as:
packages: - .
Each package directory specified must have a valid cabal file or hpack
package.yaml file present. Note that the subdirectories of the
directory are not searched for cabal files. Subdirectories will have
to be specified as independent items in the list of packages.
Meaning that your project has exactly one package, and it is located in the current directory.
Project packages are different from snapshot dependencies (via
resolver) and extra dependencies (via
extra-deps) in multiple
- Project packages will be built by default with a
stack buildwithout specific targets. Dependencies will only be built if they are depended upon.
- Test suites and benchmarks may be run for project packages. They are never run for extra dependencies.
Legacy syntax Prior to Stack 1.11, it was possible to specify
dependencies in your
packages configuration value as well. This
support has been removed to simplify the file format. Instead, these
values should be moved to
extra-deps. As a concrete example, you
packages: - . - location: git: https://github.com/bitemyapp/esqueleto.git commit: 08c9b4cdf977d5bcd1baba046a007940c1940758 extra-dep: true - location: git: https://github.com/yesodweb/wai.git commit: 6bf765e000c6fd14e09ebdea6c4c5b1510ff5376 subdirs: - wai-extra extra-dep: true extra-deps: - streaming-commons-0.2.0.0 - time-1.9.1 - yesod-colonnade-18.104.22.168 - yesod-elements-1.1
packages: - . extra-deps: - streaming-commons-0.2.0.0 - time-1.9.1 - yesod-colonnade-22.214.171.124 - yesod-elements-1.1 - git: https://github.com/bitemyapp/esqueleto.git commit: 08c9b4cdf977d5bcd1baba046a007940c1940758 - git: https://github.com/yesodweb/wai.git commit: 6bf765e000c6fd14e09ebdea6c4c5b1510ff5376 subdirs: - wai-extra
And, in fact, the
packages value could be left off entirely since
it's using the default value.
This field allows you to specify extra dependencies on top of what is
defined in your snapshot (specified in the
resolver field mentioned
above). These dependencies may either come from a local file path or a
Pantry package location.
For the local file path case, the same relative path rules as apply to
Pantry package locations allow you to include dependencies from three different kinds of sources:
- Archives (tarballs or zip files, either local or over HTTP(S))
- Git or Mercurial repositories
Here's an example using all of the above:
extra-deps: - vendor/hashable - streaming-commons-0.2.0.0 - time-1.9.1 - yesod-colonnade-126.96.36.199 - yesod-elements-1.1 - git: https://github.com/bitemyapp/esqueleto.git commit: 08c9b4cdf977d5bcd1baba046a007940c1940758 - url: https://github.com/yesodweb/wai/archive/6bf765e000c6fd14e09ebdea6c4c5b1510ff5376.tar.gz subdirs: - wai-extra - github: snoyberg/conduit commit: 2e3e41de93821bcfe8ec6210aeca21be3f2087bf subdirs: - network-conduit-tls
extra-deps value is provided, it defaults to an empty list,
For more information on the format for specifying dependencies, please see the Pantry docs.
Flags can be set for each package separately, e.g.
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.
Packages which, when present in the snapshot specified in
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.yamlfile (e.g., for license reasons)
- Prevent overriding of a global package like
Cabal. For more information, see stackage#4425
- When using a custom GHC build, avoid incompatible packages (see this comment).
drop-packages: - Cabal - buggy-package - package-with-unacceptable-license
Since Stack 2.0
A user-message is inserted by
stack init when it omits packages or adds
external dependencies. For example:
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 '
This messages is displayed every time the config is loaded by stack and serves 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.
Non-project config options may go in the global config (
/etc/stack/config.yaml) or the user config (
See Docker integration.
See Nix integration.
Integer indicating how many simultaneous downloads are allowed to happen
Strip out the "Loading ..." lines from GHC build output, produced when using Template Haskell
Target directory for
stack install and
stack build --copy-bins.
Since Stack 1.11, this field may only be used to specify a single package index, which must use the Hackage Security format. For the motivation for this change, please see issue #4137. Therefore, this field is most useful for providing an alternate Hackage mirror either for:
- Bypassing a firewall
- Faster download speeds
The following is the default setting for this field:
package-indices: - download-prefix: https://hackage.haskell.org/ hackage-security: keyids: - 0a5c7ea47cd1b15f01f5f51a33adda7e655bc0f0b0615baa8e271f4c3351e21d - 1ea9ba32c526d1cc91ab5e5bd364ec5e9e8cb67179a471872f6e26f0ae773d42 - 280b10153a522681163658cb49f632cde3f38d768b736ddbc901d99a1a772833 - 2a96b1889dc221c17296fcc2bb34b908ca9734376f0f361660200935916ef201 - 2c6c3627bd6c982990239487f1abd02e08a02e6cf16edb105a8012d444d870c3 - 51f0161b906011b52c6613376b1ae937670da69322113a246a09f807c62f6921 - 772e9f4c7db33d251d5c6e357199c819e569d130857dc225549b40845ff0890d - aa315286e6ad281ad61182235533c41e806e5a787e0b6d1e7eef3f09d137d2e9 - fe331502606802feac15e514d9b9ea83fee8b6ffef71335479a2e68d84adc6b0 key-threshold: 3 # number of keys required # ignore expiration date, see https://github.com/commercialhaskell/stack/pull/4614 ignore-expiry: true
If you provide a replacement index which does not mirror Hackage, it is likely that you'll end up with significant breakage, such as most snapshots failing to work.
Note: since Stack v2.1.3,
ignore-expiry was changed to
default. For more information on this change, see
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.
false unless the Docker or Nix integration is enabled.
In a Nix-enabled configuration, stack is incompatible with
# Turn on system GHC system-ghc: true
Whether or not to automatically install GHC when necessary. Since
Stack 1.5.0, the default is
true, which means Stack will not ask you
before downloading and installing GHC.
Should we skip the check to confirm that your system GHC version (on the PATH)
matches what your project expects? Default is
Require a version of stack within the specified range
to be used for this project. Example:
require-stack-version: "== 0.1.*"
Set the architecture and operating system for GHC, build directories, etc. Values are those recognized by Cabal, e.g.:
arch: i386, x86_64 os: windows, linux
You likely only ever want to change the arch value. This can also be set via the command line.
A list of extra paths to be searched for header files and libraries, respectively. Paths should be absolute
extra-include-dirs: - /opt/foo/include extra-lib-dirs: - /opt/foo/lib
Since these are system-dependent absolute paths, it is recommended that you
specify these in your
config.yaml within the stack root (usually,
or, on Windows,
%LOCALAPPDATA%\Programs\stack). 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.
Specify a path to gcc explicitly, rather than relying on the normal path resolution.
Use an Hpack executable, rather than using the bundled Hpack.
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< 188.8.131.52 and 184.108.40.206 would both match 7.8.4. This is useful to allow for custom patch levels of a compiler. This is the default
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
Overrides the compiler version in the resolver. Note that the
flag also applies to the version numbers. This uses the same syntax as compiler
ghc-8.6.5. This can be used to override the
compiler for a Stackage snapshot, like this:
resolver: lts-14.20 compiler: ghc-8.6.4 compiler-check: match-exact
Building GHC from source (experimental)¶
Stack supports building the GHC compiler from source. The version to build and to use is defined by a a Git commit ID and an Hadrian "flavour" (Hadrian is the build system of GHC) with the following syntax:
In the following example the commit ID is "5be7ad..." and the flavour is "quick":
By default the code is retrieved from the main GHC repository. If you want to select another repository, set the "compiler-repository" option:
compiler-repository: git://my/ghc/repository # default # compiler-repository: https://gitlab.haskell.org/ghc/ghc.git
Note that Stack doesn't check the compiler version when it uses a compiler built from source. Moreover 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). Hint: for faster build times, use Hadrian flavours that disable documentation generation.
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.
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/...
Building GHC from source requires a working GHC (known as the bootstrap
compiler). As we use a Stack based version of Hadrian (
GHC sources), the bootstrap compiler is configured into
fully managed by Stack.
Allows specifying per-package and global GHC options:
ghc-options: # All packages "$locals": -Wall "$targets": -Werror "$everything": -O2 some-package: -DSOME_CPP_FLAG
Since 1.6.0, 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
for reasoning). This can lead to unpredictable behavior by affecting
your snapshot packages.
The behavior of the
keys mirrors the behavior for the
apply-ghc-options setting, which affects
command line parameters.
NOTE: Prior to version 1.6.0, the
$everything keys were not supported. Instead, you could use
the behavior represented now by
$everything. It is highly
recommended to switch to the new, more expressive, keys.
Which packages do ghc-options on the command line get applied to? Before 0.1.6, the default value was
apply-ghc-options: locals # all local packages, the default # apply-ghc-options: targets # all local packages that are targets # apply-ghc-options: everything # applied even to snapshot and extra-deps
everything is a slightly dangerous value, as it can break invariants about your snapshot database.
Should we rebuild a package when its GHC options change? Before 0.1.6, this was a non-configurable true. However, in most cases, the flag is used to affect optimization levels and warning behavior, for which GHC itself doesn't actually recompile the modules anyway. Therefore, the new behavior is to not recompile on an options change, but this behavior can be changed back with the following:
Options which are passed to the configure step of the Cabal build process.
These can either be set by package name, or using the
$locals special keys. These special keys have the same
meaning as in
configure-options: $everything: - --with-gcc - /some/path my-package: - --another-flag
Specify a variant binary distribution of GHC to use. Known values:
standard: This is the default, uses the standard GHC binary distribution
integersimple: Use a GHC bindist that uses integer-simple instead of GMP
- any other value: Use a custom GHC bindist. You should specify
setup-info or setup-info-locations
stack setupknows where to download it, or pass the
stack setup --ghc-bindistargument on the command-line
This option is incompatible with
Specify a specialized architecture bindist to use. Normally this is
determined automatically, but you can override the autodetected value here.
Possible arguments include
Possible usages of this config are:
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.
setup-info dictionary specifies locations for installation of Haskell-related tooling - it maps
(Tool, Platform, Version) to the location where it can be obtained, such as
(GHC, Windows64, 8.6.5) to the url hosting the
*.tar.xz for GHC's installation.
By default, it's obtained from stack-setup-2.yaml.
setup-info dictionary is constructed in the following order:
setup-info yaml configuration - inline config
--setup-info-yaml command line arguments - urls or paths, multiple locations may be specified.
setup-info-locations yaml configuration - urls or paths
The first location which specifies the location of a tool
(Tool, Platform, Version) takes precedence, so one can extend the default tools with a fallback to the default
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 - https://github.com/commercialhaskell/stackage-content/raw/master/stack/stack-setup-2.yaml
setup-info location is included only if no locations in the
setup-info-locations config or the
--setup-info-yaml command line argument were specified.
Thus the following will cause
stack setup not to consult github for the
setup-info-locations: - C:/stack-offline/my-stack-setup.yaml
Relative paths are resolved relative to the
stack.yaml file - either in the local project or the global
stack.yaml in the stack directory.
Relative paths may also be used inside paths to tool installs - such as for ghc or 7z, which allows vendoring the tools inside a monorepo. For example:
- src/ - installs/ - my-stack-setup.yaml - 7z.exe - 7z.dll - ghc-8.2.2.tar.xz - stack.yaml
In the project's
setup-info-locations: - installs/my-stack-setup.yaml
sevenzexe-info: url: "installs/7z.exe" sevenzdll-info: url: "installs/7z.dll" ghc: windows64: 8.2.2: url: "installs/ghc-8.2.2.tar.xz"
Allows augmenting from where tools like GHC and msys2 (on Windows) are downloaded. Most useful for specifying locations of custom GHC binary distributions (for use with the ghc-variant option).
The format of this field is the same as in the default stack-setup-2.yaml:
setup-info: ghc: windows32-custom-foo: 7.10.2: url: "https://example.com/ghc-7.10.2-i386-unknown-mingw32-foo.tar.xz"
This configuration adds the specified setup info metadata to the default;
Specifying this config does not prevent the default
stack-setup-2.yaml from being consulted as a fallback.
If you need to replace the default setup-info, add the following:
NOTE 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. See #3550 for more information.
When using the
upload commands, this setting determines whether
the cabal file's dependencies should be modified to reflect PVP lower and upper
bounds. Values are
upper (add upper bounds),
lower bounds), and both (and upper and lower bounds). The algorithm it follows
- If an upper or lower bound already exists on a dependency, it's left alone
- When adding a lower bound, we look at the current version specified by
stack.yaml, and set it as the lower bound (e.g.,
foo >= 1.2.3)
- When adding an upper bound, we require less than the next major version
foo < 1.3)
For more information, see the announcement blog post.
NOTE Since Stack 1.5.0, each of the values listed above supports
-revision to the end of each value, e.g.
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—as
a method to ensure PVP compliance without having to proactively fix
bounds issues for Stackage maintenance.
Modify the code page for UTF-8 output when running on Windows. Default behavior is to modify.
Decide whether a custom
Setup.hs script should be run with an explicit list of
dependencies, based on the dependencies of the package itself. It associates the
name of a local package with a boolean. When it's
is built with an explicit list of packages. When it's
false (default), the
Setup.hs script is built without access to the local DB, but can access any
package in the snapshot / global DB.
Note that in the future, this will be unnecessary, once Cabal provides full support for explicit Setup.hs dependencies.
explicit-setup-deps: "*": true # change the default entropy: false # override the new default for one package
NOTE: since 1.4.0, Stack has support for Cabal's
(introduced in Cabal 1.24). If a
custom-setup block is provided in a
file, it will override the setting of
explicit-setup-deps, and instead rely
on the stated dependencies.
Ignore version bounds in .cabal files. Default is false.
Note that this also ignores lower bounds. The name "allow-newer" is chosen to match the commonly used cabal option.
Allow users other than the owner of the stack root directory (typically
to use the stack installation. The default is
false. POSIX systems only.
The intention of this option is to prevent file permission problems, for example
as the result of a
stack command executed under
The option is automatically enabled when
stack is re-spawned in a Docker process.
Allows setting build options which are usually specified on the CLI. Here are the settings with their defaults:
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: haddock-args:  # Additional arguments passed to haddock, --haddock-arguments # haddock-args: # - "--css=/home/user/my-css" open-haddocks: false # --open haddock-deps: false # if unspecified, defaults to true if haddock is set haddock-internal: false # These are inadvisable to use in your global configuration, as they make the # stack build CLI behave quite differently. test: false test-arguments: rerun-tests: true # Rerun successful tests additional-args:  # --test-arguments # additional-args: # - "--fail-fast" coverage: false no-run-tests: false bench: false benchmark-opts: benchmark-arguments: "" # benchmark-arguments: "--csv bench.csv" no-run-benchmarks: false force-dirty: false reconfigure: false cabal-verbose: false split-objs: false # Since 1.8. Starting with 2.0, the default is true interleaved-output: true # Since 1.10 ddump-dir: ""
Control which log output from local non-dependency packages to print to the console. By default, Stack will only do this when building a single target package or if the log contains warnings, to avoid generating unnecessarily verbose output.
dump-logs: none # don't dump logs even if they contain warnings dump-logs: warning # default: dump logs that contain warnings dump-logs: all # dump all logs for local non-dependency packages
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 - sets the
maintainerproperty in cabal
- author-name - sets the
authorproperty in cabal and the name used in LICENSE
- category - sets the
categoryproperty in cabal. This is used in Hackage. For examples of categories see Packages by category. It makes sense for
categoryto 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
- copyright - sets the
copyrightproperty 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
copyrightis not specified,
author-nameare used to generate the copyright property in cabal. If
yearis not specified, it defaults to the current year.
- github-username - used to generate
source-repositoryin cabal. For instance
stack new my-project new-templatewould result:
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:
templates: params: author-name: Your Name author-email: firstname.lastname@example.org category: Your Projects Category copyright: 'Copyright (c) 2020 Your Name' github-username: yourusername
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.
templates: scm-init: git
Controls whether, when using
stack upload, the user's Hackage
username and password are stored in a local file. Default: true.
Sets the address of the Hackage server to upload the package to. Default is
This flag was introduced in Stack 1.6, and removed in Stack 1.11 with the move to Pantry. You will receive a warning if this configuration value is set.
Customize the URLs where
stack looks for snapshot build plans.
The default configuration is
urls: latest-snapshot: https://www.stackage.org/download/snapshots.json
Specifies how many build tasks should be run in parallel. This can be overloaded
on the commandline via
-jN, for example
-j2. The default is to use the
number of processors reported by your CPU. One usage for this might be to avoid
running out of memory by setting it to 1, like this:
Specifies relative path of work directory (default is
.stack-work. This can
also be specified by env var or cli flag, in particular, the earlier items in
this list take precedence:
--work-dir DIRpassed on the commandline
Skips checking for and installing msys2 when stack is setting up the
environment. This is only useful on Windows machines, and usually doesn't make
sense in project configurations, just in
config.yaml. Defaults to
if this is used, it only really makes sense to use it like this:
This option specifies whether test-suites should be executed concurrently with
each-other. The default for this 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 (the default is
This option specifies additional directories to prepend to the PATH environment
variable. These will be used when resolving the location of executables, and
will also be visible in the
PATH variable of processes run by stack.
For example, to prepend
/path-to-some-dep/bin to your PATH:
extra-path: - /path-to-some-dep/bin
One thing to note is that other paths added by stack - things like the project's bin dir and the compiler's bin dir - will take precedence over those specified here (the automatic paths get prepended).
This overrides the location of the programs directory, where tools like ghc and msys get installed.
On most systems, this defaults to a folder called
within the stack root directory. On Windows, if the
variable exists, then it defaults to
follows Windows' conventions.
NOTE: On Windows, if there is a space character in the
(which may be the case if the relevant user account name and its corresponding
user profie path have a space) this may cause problems with building packages
that make use of the GNU project's
autoconf package and
script files. That may be the case particularly if there is no corresponding
short name ('8 dot 3' name) for the folder 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 override
the default location of stack's programs directory to specify an alternative
path that does not contain space characters. Examples of packages on Hackage
that make use of
This option specifies which template to use with
stack new, when none is
specified. The default is called
new-template. The other templates are listed
in the stack-templates repo.
This option specifies when to use color in output. The option is used as
color: <WHEN>, where
<WHEN> 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 color use can also be set at the command line using the equivalent
--color=<WHEN> global option. Color use set at the command line takes
precedence over that set in a yaml configuration file.
(The British English spelling (colour) is also accepted. In yaml configuration files, the American spelling is the alternative that has priority.)
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: <STYLES>, where
<STYLES> 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
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 and those codes supported on current versions of Windows in Microsoft's documentation.
For example, users of the popular Solarized Dark terminal theme might wish to set the styles as follows:
The styles can also be set at the command line using the equivalent
global option. Styles set at the command line take precedence over those set in
a yaml configuration file. (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 will use the
-fhide-source-paths option by default for GHC >= 8.2, unless this
option is set to
false as in the following example:
Build output when enabled:
... [1 of 2] Compiling Lib [2 of 2] Compiling Paths_test_pr ...
Build output when disabled:
... [1 of 2] Compiling Lib ( src/Lib.hs, .stack-work/dist/x86_64-linux-tinfo6/Cabal-220.127.116.11/build/Lib.o ) ...
When Stack notices that a new version of Stack is available, should it notify the user?
Turns on a mode where some messages are printed at WARN level instead of DEBUG level, especially useful for developers of Stack itself. For official distributed binaries, this is set to
false by default. When you build from source, it is set to
true by default.
Sets the base location of LTS Haskell/Stackage Nightly snapshots. Default is https://raw.githubusercontent.com/commercialhaskell/stackage-snapshots/master/ (as set in the
has the following effect:
lts-X.Y expands to
nightly-YYYY-MM-DD expands to
This field 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.