Changes since v3.7.1:

Behavior changes:

• Where applicable and Stack supports the GHC version, only the wired-in packages of the actual version of GHC used are treated as wired-in packages.
• Stack now recognises ghc-internal as a GHC wired-in package.
• The configuration option package-index has a new default value: the keyids key lists the keys of the Hackage root key holders applicable from 2025-07-24.
• Stack's dot command now treats --depth the same way as the ls dependencies command, so that the nodes of stack dot --external --depth 0 are the same as the packages listed by stack ls dependencies --depth 0.
• When building GHC from source, on Windows, the default Hadrian build target is reloc-binary-dist and the default path to the GHC built by Hadrian is _build/reloc-bindist.
• Stack's haddock command no longer requires a package to have a main library that exposes modules.

Other enhancements:

• Bump to Hpack 0.38.2.
• Consider GHC 9.14 to be a tested compiler and remove warnings.
• Consider Cabal 3.16 to be a tested library and remove warnings.
• From GHC 9.12.1, base is not a GHC wired-in package. In configuration files, the notify-if-base-not-boot key is introduced, to allow the exisitng notification to be muted if unwanted when using such GHC versions.
• Add flag --[no-]omit-this (default: disabled) to Stack's clean command to omit directories currently in use from cleaning (when --full is not specified).
• Add option -w as synonym for --stack-yaml.
• stack new now allows codeberg: as a service for template downloads.
• In YAML configuration files, the compiler-target and compiler-bindist-path keys are introduced to allow, when building GHC from source, the Hadrian build target and Hadrian path to the built GHC to be specified.

Bug fixes:

• --PROG-option=<argument> passes --PROG-option=<argument> (and not --PROG-option="<argument>") to Cabal (the library).
• The message S-7151 now presents as an error, with advice, and not as a bug.
• Stack's dot command now uses a box to identify all GHC wired-in packages, not just those with no dependencies (being only rts).
• Stack's dot command now gives all nodes with no dependencies in the graph the maximum rank, not just those nodes with no relevant dependencies at all (being only rts, when --external is specified).
• Improved error messages for S-4634 and S-8215.
• Improved in-app help for the --hpack-force flag.

See https://haskellstack.org/ for installation and upgrade instructions.

Changes since v3.5.1:

Other enhancements:

• Bump to Hpack 0.38.1.
• The --extra-dep option of Stack's script command now accepts a YAML value specifying any immutable extra-dep. Previously only an extra-dep in the package index that could be specified by a YAML string (for example, acme-missiles-0.3@rev:0) was accepted.

Bug fixes:

• stack script --package <pkg-name> now uses GHC's -package-id option to expose the installed package, rather than GHC's -package option. For packages with public sub-libraries, -package <pkg> can expose an installed package other than one listed by ghc-pkg list <pkg>.
• Work around ghc-pkg bug where, on Windows only, it cannot register a package into a package database that is also listed in the GHC_PACKAGE_PATH environment variable. In previous versions of Stack, this affected stack script when copying a pre-compiled package from another package database.
• On Windows, when decompressing, and extracting, tools from archive files, Stack uses the system temporary directory, rather than the root of the destination drive, if the former is on the destination drive.

Thanks to all our contributors for this release:

• Max Ulidtko
• Mike Pilgrem
• Olivier Benz
• Simon Hengel

Changes since v3.5.1:

Other enhancements:

• Bump to Hpack 0.38.1.
• The --extra-dep option of Stack's script command now accepts a YAML value specifying any immutable extra-dep. Previously only an extra-dep in the package index that could be specified by a YAML string (for example, acme-missiles-0.3@rev:0) was accepted.

Bug fixes:

• stack script --package <pkg-name> now uses GHC's -package-id option to expose the installed package, rather than GHC's -package option. For packages with public sub-libraries, -package <pkg> can expose an installed package other than one listed by ghc-pkg list <pkg>.
• Work around ghc-pkg bug where, on Windows only, it cannot register a package into a package database that is also listed in the GHC_PACKAGE_PATH environment variable. In previous versions of Stack, this affected stack script when copying a pre-compiled package from another package database.
• On Windows, when decompressing, and extracting tools, from archive files, Stack uses the system temporary directory, rather than the root of the destination drive, if the former is on the destination drive.

See https://haskellstack.org/ for installation and upgrade instructions.

Changes since v3.3.1:

Behavior changes:

• Stack will also warn (message S-8432) if there is any non-ISO/IEC 8859-1 (Latin-1) character in Stack's 'programs' path, as hsc2hs does not work if there is such a character in the path to its default template template-hsc.h.
• Stack customizes setup using Cabal, so if a setup-depends field does not mention it as a dependency, Stack warns and adds the GHC boot package as a dependency. Previously, Stack would not do so but only warn that build errors were likely.

Other enhancements:

• Bump to Hpack 0.38.0.
• In YAML configuration files, the install-msys key is introduced, to enable or disable the download and installation of Stack-supplied MSYS2 when necessary (subject to skip-msys: false). The default is the same as the install-ghc setting (including if that is set at the command line). Consequently, the default behaviour of Stack is unaffected.
• Add the stack config set install-msys command to configure the install-msys option in YAML configuration files.
• Option allow-newer-deps is no longer classified as experimental in documentation.
• stack sdist and stack upload report the version of Cabal (the library) being used to check packages.
• Add the stack config build-files command to generate (when applicable) a Cabal file from a package description in the Hpack format and/or a lock file for Stack's project-level configuration, without taking any other build steps.

Thanks to all our contributors for this release:

• Mike Pilgrem
• Olivier Benz

Changes since v3.3.1:

Behavior changes:

• Stack will also warn (message S-8432) if there is any non-ISO/IEC 8859-1 (Latin-1) character in Stack's 'programs' path, as hsc2hs does not work if there is such a character in the path to its default template template-hsc.h.
• Stack customizes setup using Cabal, so if a setup-depends field does not mention it as a dependency, Stack warns and adds the GHC boot package as a dependency. Previously, Stack would not do so but only warn that build errors were likely.

Other enhancements:

• Bump to Hpack 0.38.0.
• In YAML configuration files, the install-msys key is introduced, to enable or disable the download and installation of Stack-supplied MSYS2 when necessary (subject to skip-msys: false). The default is the same as the install-ghc setting (including if that is set at the command line). Consequently, the default behaviour of Stack is unaffected.
• Add the stack config set install-msys command to configure the install-msys option in YAML configuration files.
• Option allow-newer-deps is no longer classified as experimental in documentation.
• stack sdist and stack upload report the version of Cabal (the library) being used to check packages.

See https://haskellstack.org/ for installation and upgrade instructions.

Changes since v3.1.1:

Behavior changes:

• Stack interprets consecutive line ends in the value of the user-message project-specific configuration option as a single blank line. Previously all line ends were interpreted as white space.
• Stack no longer supports Docker versions before Docker 1.9.1 and, consequently, if a Docker container is not being run 'detached', its standard input channel will always be kept open. (Before Docker 1.9.1 the use of an interactive container could hang in certain circumstances.)
• On Windows, Stack will always warn (message S-8432) if there is a space character in Stack's 'programs' path, as GHC 9.4.1 and later do not work if there is a space in the path to the ghc executable. S-8432 now presents as a warning and not an error.
• Stack respects the --no-run-tests and --no-run-benchmarks flags when determining build actions. Previously Stack respected the flags when executing the run test suites or run benchmarks actions for each targeted project package.

Other enhancements:

• Consider GHC 9.10 to be a tested compiler and remove warnings.
• Consider Cabal 3.12 to be a tested library and remove warnings.
• Add flags --run-tests and --run-benchmarks (the existing defaults) to Stack's build command, which take precedence over the existing no-run-tests and no-run-benchmarks configuration options, respectively.
• In configuration files, the notify-if-no-run-tests and notify-if-no-run-benchmarks keys are introduced, to allow the exisitng notification to be muted if unwanted.

Bug fixes:

• Stack's in-app messages refer to https://haskellstack.org as currently structured. (Most URLs in older Stack versions are redirected.)
• Stack's upgrade command only treats the current running Stack executable as 'stack' if the executable file is named stack or, on Windows, stack.exe. Previously only how it was invoked was considered.
• stack test --no-run-tests --dry-run no longer reports that Stack would test project packages with test suites and stack bench --no-run-benchmarks --dry-run no longer reports that Stack would benchmark project packages with benchmarks.
• StackSetupShim compiles with Cabal >= 3.14.0.0.

Thanks to all our contributors for this release:

• Andrew Nguyen
• Luka Leer
• Mike Pilgrem
• Olivier Benz

Changes since v3.1.1:

Behavior changes:

• Stack interprets consecutive line ends in the value of the user-message project-specific configuration option as a single blank line. Previously all line ends were interpreted as white space.
• Stack no longer supports Docker versions before Docker 1.9.1 and, consequently, if a Docker container is not being run 'detached', its standard input channel will always be kept open. (Before Docker 1.9.1 the use of an interactive container could hang in certain circumstances.)
• On Windows, Stack will always warn (message S-8432) if there is a space character in Stack's 'programs' path, as GHC 9.4.1 and later do not work if there is a space in the path to the ghc executable. S-8432 now presents as a warning and not an error.
• Stack respects the --no-run-tests and --no-run-benchmarks flags when determining build actions. Previously Stack respected the flags when executing the run test suites or run benchmarks actions for each targeted project package.

Other enhancements:

• Consider GHC 9.10 to be a tested compiler and remove warnings.
• Consider Cabal 3.12 to be a tested library and remove warnings.
• Add flags --run-tests and --run-benchmarks (the existing defaults) to Stack's build command, which take precedence over the existing no-run-tests and no-run-benchmarks configuration options, respectively.
• In configuration files, the notify-if-no-run-tests and notify-if-no-run-benchmarks keys are introduced, to allow the exisitng notification to be muted if unwanted.

Bug fixes:

• Stack's in-app messages refer to https://haskellstack.org as currently structured. (Most URLs in older Stack versions are redirected.)
• Stack's upgrade command only treats the current running Stack executable as 'stack' if the executable file is named stack or, on Windows, stack.exe. Previously only how it was invoked was considered.
• stack test --no-run-tests --dry-run no longer reports that Stack would test project packages with test suites and stack bench --no-run-benchmarks --dry-run no longer reports that Stack would benchmark project packages with benchmarks.
• StackSetupShim compiles with Cabal >= 3.14.0.0.

See https://haskellstack.org/ for installation and upgrade instructions.

Release notes:

• The change in major version from 2.x to 3.1 marks the dropping of support for versions of GHC before 8.4, deprecated in Stack 2.15.1.

Changes since v2.15.7:

Behavior changes:

• Stack uses the version of the Cabal package that comes with the specified version of GHC. Stack no longer supports such Cabal versions before 2.2, which came with versions of GHC before 8.4. Consequently, the init command will not try LTS Haskell before 12.0.
• The init command initialises stack.yaml with a snapshot key rather than a resolver key.
• After installing GHC or another tool, Stack deletes the archive file which provided the tool.
• Remove hidden flag --skip-intermediate-deps, effectively deprecated since Stack 1.3.0, from ghci and repl commands.
• The haddock --haddock-for-hackage command only seeks to create an archive of the <package_version>-docs directory for build targets and if flags excluding the building of project packages are not set.
• The predecessor of configuration option package-index, package-indices (deprecated in Stack 2.9.3) has been removed as an alternative option.
• If a build target is a package identifier, and the package version is not in the snapshot or the package index, Stack will report an error when the target is parsed. Previously, if another version of the package was in the snapshot, Stack would construct the build plan with that other version or, if it was not, Stack would defer an error to the construction of the build plan.
• The list command, with a specified snapshot and package, also reports the version of the package included indirectly in the snapshot (as a boot package of the compiler specified by the snapshot).
• stack build --flag *:[-]<flag_name> now only applies the flag setting to packages for which the Cabal flag is defined, as opposed to all packages.
• On Unix-like operating systems, drop support for /etc/stack/config, deprecated in Stack 0.1.6.0.
• Drop support for, in the Stack root, directory global and file stack.yaml, both deprecated in Stack 0.1.6.0.

Other enhancements:

• Bump to Hpack 0.37.0.
• In YAML configuration files, the msys-environment key is introduced to allow, on Windows, the MSYS2 environment to be specified. The default environment is still MINGW64 on 64-bit Windows and MINGW32 on 32-bit Windows.
• In YAML configuration files, the default-init-snapshot key is introduced to allow a default snapshot to be specified for use with the stack init command, as if it had been specified at the command line.
• Add flags --haddock-executables, --haddock-tests and --haddock-benchmarks to Stack's build command (including the haddock synonym for build --haddock) to enable also building Haddock documentation for executables, test suites and benchmarks. Due to a bug in Cabal (the library), Stack will ignore the flags with a warning for GHC versions before 9.4.
• Add flag --[no-]save-hackage-creds to Stack's upload command, which takes precedence over the existing save-hackage-creds configuration option.
• In YAML configuration files, the global-hints-location key is introduced to allow the location of the global hints YAML specification file to be specified.
• By default, Hpack 0.20.0 or later will decline to overwrite a Cabal file that was modified manually. In YAML configuration files, the hpack-force key is introduced to allow Hpack to overwrite such a Cabal file. The corresponding --hpack-force flag is also added.
• Add the stack config set recommend-stack-upgrade command to configure whether or not Stack should notify the user if it identifes a new version of Stack is available in YAML configuration files.
• Add the ls globals command to list all global packages for the version of GHC specified by the snapshot.
• Add stack -h (equivalent to stack --help).
• In YAML configuration files, the file-watch-hook key is introduced to allow --file-watch post-processing to be customised with a executable or sh shell script.
• Add flag --[no-]allow-newer to Stack's build command, which takes precedence over the existing allow-newer configuration option.

Bug fixes:

• The config set snapshot and config set resolver commands now respect the presence of a synoymous key.
• The config set commands support existing keys only in the form key: value on a single line. The commands now recognise that a line key: does not have that form.
• On Unix-like operating systems, the test --coverage command now finds package keys even for very long package names.
• The Error S-6362 message now acknowledges when the wanted compiler has been specified at the command line.
• Fix a regression, introduced in Stack 2.11.1, that caused the script command to parse an (otherwise ignored) project-level configuration file.
• Stack no longer makes recommendations about a project-level configuration file when only a global configuration file is in use.
• Fix a regression, introduced in Stack 2.15.7, that caused GHC 8.10.7 or earlier to fail to build a package with a Custom build type, if GHC option -haddock was specified.

Thanks to all our contributors for this release:

• Michael Pilosov
• Mike Pilgrem
• Olivier Benz
• Phil de Joux
• theophilebatoz

Release notes:

• The change in major version from 2.x to 3.1 marks the dropping of support for versions of GHC before 8.4, deprecated in Stack 2.15.1.

Changes since v2.15.7:

Behavior changes:

• Stack uses the version of the Cabal package that comes with the specified version of GHC. Stack no longer supports such Cabal versions before 2.2, which came with versions of GHC before 8.4. Consequently, the init command will not try LTS Haskell before 12.0.
• The init command initialises stack.yaml with a snapshot key rather than a resolver key.
• After installing GHC or another tool, Stack deletes the archive file which provided the tool.
• Remove hidden flag --skip-intermediate-deps, effectively deprecated since Stack 1.3.0, from ghci and repl commands.
• The haddock --haddock-for-hackage command only seeks to create an archive of the <package_version>-docs directory for build targets and if flags excluding the building of project packages are not set.
• The predecessor of configuration option package-index, package-indices (deprecated in Stack 2.9.3) has been removed as an alternative option.
• If a build target is a package identifier, and the package version is not in the snapshot or the package index, Stack will report an error when the target is parsed. Previously, if another version of the package was in the snapshot, Stack would construct the build plan with that other version or, if it was not, Stack would defer an error to the construction of the build plan.
• The list command, with a specified snapshot and package, also reports the version of the package included indirectly in the snapshot (as a boot package of the compiler specified by the snapshot).
• stack build --flag *:[-]<flag_name> now only applies the flag setting to packages for which the Cabal flag is defined, as opposed to all packages.
• On Unix-like operating systems, drop support for /etc/stack/config, deprecated in Stack 0.1.6.0.
• Drop support for, in the Stack root, directory global and file stack.yaml, both deprecated in Stack 0.1.6.0.

Other enhancements:

• Bump to Hpack 0.37.0.
• In YAML configuration files, the msys-environment key is introduced to allow, on Windows, the MSYS2 environment to be specified. The default environment is still MINGW64 on 64-bit Windows and MINGW32 on 32-bit Windows.
• In YAML configuration files, the default-init-snapshot key is introduced to allow a default snapshot to be specified for use with the stack init command, as if it had been specified at the command line.
• Add flags --haddock-executables, --haddock-tests and --haddock-benchmarks to Stack's build command (including the haddock synonym for build --haddock) to enable also building Haddock documentation for executables, test suites and benchmarks. Due to a bug in Cabal (the library), Stack will ignore the flags with a warning for GHC versions before 9.4.
• Add flag --[no-]save-hackage-creds to Stack's upload command, which takes precedence over the existing save-hackage-creds configuration option.
• In YAML configuration files, the global-hints-location key is introduced to allow the location of the global hints YAML specification file to be specified.
• By default, Hpack 0.20.0 or later will decline to overwrite a Cabal file that was modified manually. In YAML configuration files, the hpack-force key is introduced to allow Hpack to overwrite such a Cabal file. The corresponding --hpack-force flag is also added.
• Add the stack config set recommend-stack-upgrade command to configure whether or not Stack should notify the user if it identifes a new version of Stack is available in YAML configuration files.
• Add the ls globals command to list all global packages for the version of GHC specified by the snapshot.
• Add stack -h (equivalent to stack --help).
• In YAML configuration files, the file-watch-hook key is introduced to allow --file-watch post-processing to be customised with a executable or sh shell script.

Bug fixes:

• The config set snapshot and config set resolver commands now respect the presence of a synoymous key.
• The config set commands support existing keys only in the form key: value on a single line. The commands now recognise that a line key: does not have that form.
• On Unix-like operating systems, the test --coverage command now finds package keys even for very long package names.
• The Error S-6362 message now acknowledges when the wanted compiler has been specified at the command line.
• Fix a regression, introduced in Stack 2.11.1, that caused the script command to parse an (otherwise ignored) project-level configuration file.
• Stack no longer makes recommendations about a project-level configuration file when only a global configuration file is in use.

See https://haskellstack.org/ for installation and upgrade instructions.

Release notes:

• This release fixes potential bugs.
• The hash that Stack uses to distinguish one build plan from another has changed for plans that set (as opposed to unset) manually Cabal flags for immutable dependencies. This will cause Stack to rebuild dependencies for such plans.

Changes since v2.15.5:

Major changes:

• Stack 2.15.5 and earlier cannot build with Cabal (the library) version 3.12.0.0. Stack can now build with that Cabal version.

Behavior changes:

• Stack's StackSetupShim executable, when called with repl and stack-initial-build-steps, no longer uses Cabal's replHook to apply initialBuildSteps but takes a more direct approach.

Bug fixes:

• Fix a regression introduced in Stack 2.15.1 that caused a 'no operation' stack build to be slower than previously.
• The hashes that Stack uses to distinguish one build plan from another now include the Cabal flags for immutable dependencies set manually. Previously, in error, only such flags that were unset manually were included.

Thanks to all our contributors for this release:

• Jörg Thalheim
• Mike Pilgrem