Announcing the first release in the stack-2.1 series!

The Stack 2 release represents a series of significant changes to how Stack works internally. For the vast majority of cases, these changes are backwards compatible, in that existing projects will continue to build in the same way with Stack 2 as they did with Stack 1. The large version bump is due to the fundamental internal changes to cache handling, database storage (using SQLite in place of binary files), implicit snapshots (which greatly improve the precompiled cache), and moving to Pantry. We have also removed some less used features, as listed in the release notes below.

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

Changes since v1.9.3

Major changes:

• Switch over to pantry for managing packages. This is a major change to Stack’s internals, and affects user-visible behavior in a few places. Some highlights:
  • Drop support for multiple package indices and legacy 00-index.tar style indices. See #4137.
  • Support for archives and repos in the packages section has been removed. Instead, you must use extra-deps for such dependencies. packages now only supports local filepaths.
  • Add support for Git repositories containing (recursive) submodules.
  • Addition of new configuration options for specifying a “pantry tree” key, which provides more reproducibility around builds, and (in the future) will be used for more efficient package content downloads. You can also specify package name and version for more efficient config parsing. * NOTE The new stack freeze command provides support for automatically generating this additional information.
  • Package contents and metadata are stored in an SQLite database in place of files on the filesystem. The pantry library can be used for interacting with these contents.
  • Internally, Stack has changed many datatypes, including moving to Cabal’s definition of many data types. As a result of such changes, existing cache files will in general be invalidated, resulting in Stack needing to rebuild many previously cached builds in the new version. Sorry :(.
  • A new command, stack freeze has been added which outputs project and snapshot definitions with dependencies pinned to their exact versions.
  • The ignore-revision-mismatch setting is no longer needed, and has been removed.
  • Overriding GHC boot packages results in any other GHC boot packages depending on it being no longer available as a dependency, such packages need to be added explicitly when needed. See [#4510] (https://github.com/commercialhaskell/stack/issues/4510).
  • Cabal solver integration was not updated to support newer cabal-install versions so stack solver command was removed as well as a related option --solver from stack new and stack init.
• Upgrade to Cabal 2.4
  • Note that, in this process, the behavior of file globbing has been modified to match that of Cabal. In particular, this means that for Cabal spec versions less than 2.4, *.txt will match foo.txt, but not foo.2.txt.
• Remove the stack image command. With the advent of Docker multistage builds, this functionality is no longer useful. For an example, please see Building Haskell Apps with Docker.
• Support building GHC from source (experimental)
  • Stack now supports building and installing GHC from source. The built GHC is uniquely identified by a commit id and an Hadrian “flavour” (Hadrian is the newer GHC build system), hence compiler can be set to use a GHC built from source with ghc-git-COMMIT-FLAVOUR
• stack.yaml now supports a configure-options, which are passed directly to the configure step in the Cabal build process. See #1438
• Remove support for building GHCJS itself. Future releases of Stack may remove GHCJS support entirely.
• Support for lock files for pinning exact project dependency versions

Behavior changes:

• stack.yaml now supports snapshot: a synonym for resolver. See #4256
• stack script now passes -i -idir in to the ghc invocation. This makes it so that the script can import local modules, and fixes an issue where .hs files in the current directory could affect interpretation of the script. See #4538
• When using stack script, custom snapshot files will be resolved relative to the directory containing the script.
• Remove the deprecated --upgrade-cabal flag to stack setup.
• Support the drop-packages field in stack.yaml
• Remove the GPG signing code during uploads. The GPG signatures have never been used yet, and there are no plans to implement signature verification.
• Remove the --plain option for the exec family of commands
• Always use the --exact-configuration Cabal configuration option when building (should mostly be a non-user-visible enhancement).
• No longer supports Cabal versions older than 1.19.2. This means projects using snapshots earlier than lts-3.0 or nightly-2015-05-05 will no longer build.
• Remove the stack docker cleanup command. Docker itself now has docker image prune and docker container prune, which you can use instead.
• Interleaved output is now turned on by default, see #4702. In addition, the packagename> prefix is no longer included in interelaved mode when only building a single target.
• The -fhide-source-paths GHC option is now enabled by default and can be disabled via the hide-source-paths configuration option in stack.yaml. See #3784
• Stack will reconfigure a package if you modify your PATH environment variable. See #3138.
• For GHC 8.4 and later, disable the “shadowed dependencies” workaround. This means that Stack will no longer have to force reconfigures as often. See #3554.
• When building a package, Stack takes a lock on the dist directory in use to avoid multiple runs of Stack from trampling each others’ files. See #2730.
• Stack will check occassionally if there is a new version available and prompt the user to upgrade. This will not incur any additional network traffic, as it will piggy-back on the existing Hackage index updates. You can set recommend-stack-upgrade: false to bypass this. See #1681.
• stack list-dependencies has been removed in favour of stack ls dependencies.
• The new default for --docker-auto-pull is enabled. See #3332.

Other enhancements:

• Support MX Linux in get-stack.sh. Fixes #4769.
• Defer loading up of files for local packages. This allows us to get plan construction errors much faster, and avoid some unnecessary work when only building a subset of packages. This is especially useful for the curator use case.
• Existing global option --color=WHEN is now also available as a non-project-specific yaml configuration parameter color:.
• Adopt the standard proposed at http://no-color.org/, that color should not be added by default if the NO_COLOR environment variable is present.
• New command stack ls stack-colors lists the styles and the associated ‘ANSI’ control character sequences that stack uses to color some of its output. See stack ls stack-colors --help for more information.
• New global option --stack-colors=STYLES, also available as a non-project-specific yaml configuration parameter, allows a stack user to redefine the default styles that stack uses to color some of its output. See stack --help for more information.
• British English spelling of ‘color’ (colour) accepted as an alias for --color, --stack-colors, stack ls stack-colors at the command line and for color: and stack-colors: in yaml configuration files.
• New build option --ddump-dir. (See #4225)
• Stack parses and respects the preferred-versions information from Hackage for choosing latest version of a package in some cases, e.g. stack unpack packagename.
• The components output in the The main module to load is ambiguous message now include package names so they can be more easily copy-pasted.
• Git repos are shared across multiple projects. See #3551
• Use en_US.UTF-8 locale by default in pure Nix mode so programs won’t crash because of Unicode in their output #4095
• Add --tree to ls dependencies to list dependencies as tree. #4101
• Add --pedantic to ghci to run with -Wall and -Werror #4463
• Add --cabal-files flag to stack ide targets command.
• Add --stdout flag to all stack ide subcommands.
• Use batches when unregistering packages with ghc-pkg. (See #2662)
• get-stack script now works on Windows CI machines of Appveyor, Travis and Azure Pipelines. See #4535/
• Show snapshot being used when stack ghci is invoked outside of a project directory. See #3651
• The script interpreter now accepts a --extra-dep flag for adding packages not present in the snapshot. Currently, this only works with packages from Hackage, not Git repos or archives.
• When using the script interpreter with --optimize or --compile, Stack will perform an optimization of checking whether a newer executable exists, making reruns significantly faster. There’s a downside to this, however: if you have a multifile script, and change one of the dependency modules, Stack will not automatically detect and recompile.
• stack clean will delete the entire .stack-work/dist directory, not just the relevant subdirectory for the current GHC version. See #4480.
• Add stack purge as a shortcut for stack clean --full. See #3863.
• Both stack dot and stack ls dependencies accept a --global-hints flag to bypass the need for an installed GHC. See #4390.
• Add the stack config env command for getting shell script environment variables. See #620.
• Less verbose output from stack setup on Windows. See #1212.
• Add an optional ignore-expiry flag to the hackage-security section of the ~/.stack/config.yaml. It allows to disable timestamp expiration verification just like cabal --ignore-expiry does. The flag is not enabled by default so that the default functionality is not changed.
• Include default values for most command line flags in the --help output. See #893.
• Set the GHC_ENVIRONMENT environment variable to specify dependency packages explicitly when running test. This is done to prevent ambiguous module name errors in doctest tests.
• get-stack script now works on Windows CI machines of Appveyor, Travis and Azure Pipelines. See #4535
• Warn when a Docker image does not include a PATH environment variable. See #2472
• When using system-ghc: true, Stack will now find the appropriate GHC installation based on the version suffix, allowing you to more easily switch between various system-installed GHCs. See #2433.
• stack init will now support create a stack.yaml file without any local packages. See #2465
• Store caches in SQLite database instead of files.
• No longer use “global” Docker image database (docker.db).
• User config files are respected for the script command. See #3705, #3887.
• Set the GHC_ENVIRONMENT environment variable to - to tell GHC to ignore any such files when GHC is new enough (>= 8.4.4), otherwise simply unset the variable. This allows Stack to have control of package databases when running commands like stack exec ghci, even in the presence of implicit environment files created by cabal new-build. See #4706.
• Use a database cache table to speed up discovery of installed GHCs
• You can specify multiple --test-arguments options. See #2226
• Windows terminal width detection is now done. See #3588
• On Windows, informs users if the ‘programs’ path contains a space character and further warns users if that path does not have an alternative short (‘8 dot 3’) name, referencing the local-programs-path configuration option. See #4726
• Add --docker-mount-mode option to set the Docker volume mount mode for performance tuning on macOS.

Bug fixes:

• Ignore duplicate files for a single module when a Haskell module was generated from a preprocessor file. See #4076.
• Only track down components in current directory if there are no hs-source-dirs found. This eliminates a number of false-positive warnings, similar to #4076.
• Handle a change in GHC’s hi-dump format around addDependentFile, which now includes a hash. See yesodweb/yesod#1551
• Fix subdirs for git repos in extra-deps to match whole directory names. Also fixes for subdirs: .. See #4292
• Fix for git packages to update submodules to the correct state. See #4314
• Add --cabal-files flag to stack ide targets command.
• Don’t download ghc when using stack clean.
• Support loading in GHCi definitions from symlinked C files. Without this patch, Stack will try to find object files in the directory pointed to by symlinks, while GCC will produce the object files in the original directory. See #4402
• Fix handling of GitHub and URL templates on Windows. See commercialhaskell/stack#4394
• Fix --file-watch not responding to file modifications when running inside docker on Mac. See #4506
• Using --ghc-options with stack script --compile now works.
• Ensure the detailed-0.9 type tests work. See #4453.
• Extra include and lib dirs are now order-dependent. See #4527.
• Apply GHC options when building a Setup.hs file. See #4526.
• Stack handles ABI changes in FreeBSD 12 by differentiating that version from previous.
• Help text for the templates subcommand now reflects behaviour in stack 1.9 — that it downloads and shows a help file, rather than listing available templates.
• Fix detection of aarch64 platform (this broke when we upgraded to a newer Cabal version).
• Docker: fix detecting and pulling missing images with --docker-auto-pull, see #4598
• Hackage credentials are not world-readable. See #2159.
• Warnings are dumped from logs even when color is enabled. See #2997
• stack init will now work for cabal files with sublibraries. See #4408
• When the Cabal spec version is newer than the global Cabal version, build against the snapshot’s Cabal library. See #4488
• Docker: fix detection of expected subprocess failures. This fixes downloading a compatible stack executable when the host stack is not compatible with the Docker image (on Linux), and doesn’t show an unnecessary extra error when the in-container re-exec’ed stack exits with failure.
• The stack ghci command’s --ghc-options flag now parses multiple options. See #3315.

Thanks to all our contributors for this release:

• Adam Bergmark
• Akshay Mankar
• Aleksey Kozin
• ALeX Kazik
• Alexey Kozin
• Alexey Kuleshevich
• Anders Kaseorg
• Anders Kiel Hovgaard
• Artyom Kazak
• Bastian Krol
• Björn Gohla
• Brad Neimann
• Brandon Chinn
• Colin Woodbury
• Cthulhu.Den
• dadepo
• Daniel Gröber
• David Baynard
• David Spies
• David Vollbracht
• dbaynard
• Emanuel Borsboom
• favonia
• flip111
• Florjan Bartol
• Gleb Popov
• Hussein Ait-Lahcen
• Isumi Feng
• Janfel
• Jurijs Oniscuks
• Kayla Ngan
• Kirill Zaborsky
• Magicloud
• Matt Audesse
• Mauricio Fierro
• Michael Sloan
• Michael Snoyman
• Mihai Maruseac
• Mike Pilgrem
• Neil Mitchell
• NeonGraal
• Niklas Hambüchen
• penteract
• Phil de Joux
• Raghu Kaippully
• Sibi
• Sibi Prabakaran
• Simon Hengel
• skapazzo
• Sylvain HENRY
• Sylvain Henry
• Taekyung
• Timothy Clem
• Tom Sydney Kerckhove
• Valery V. Vorotyntsev
• Vance Palacio
• waddlaw
• 欧阳泽