haskell-flake
haskell-flake scans your flake files for Haskell projects and
turns them into packages using the Nixpkgs Haskell infrastructure.
It also provides checks and devShells
Multiple projects can be declared to represent each package set, which is great for GHCJS frontends.
Installation
To use these options, add to your flake inputs:
haskell-flake.url = "github:srid/haskell-flake";
and inside the mkFlake:
imports = [
inputs.haskell-flake.flakeModule
];
Run nix flake lock and you're set.
Options
flake.haskellFlakeProjectModules
A lazy attrset of haskellProjects.<name> modules that can be
imported in other flakes.
Type: lazy attribute set of module
Default: Package and dependency information for this project exposed for reuse in another flake, when using this project as a Haskell dependency.
The ‘output’ module of the default project is included by default,
returning defaults.projectModules.output.
Declared by:
perSystem.haskellProjectTests
Patch an existing haskellProject to run some checks. This module
will create a flake check automatically.
Type: lazy attribute set of (submodule)
Default:
{ }
Declared by:
perSystem.haskellProjectTests.<name>.expect
Arbitrary expression to evaluate as part of the generated flake check
Type: raw value
Declared by:
perSystem.haskellProjectTests.<name>.extraHaskellProjectConfig
Extra configuration to apply to the patched haskell-flake project.
Type: module
Default:
{ }
Declared by:
perSystem.haskellProjectTests.<name>.from
Which haskellProjects.?? to patch.
Type: string
Default:
"default"
Declared by:
perSystem.haskellProjectTests.<name>.patches
List of patches to apply to the project root.
Each patch can be a path to the diff file, or inline patch string.
Type: list of (absolute path or string)
Declared by:
perSystem.haskellProjects
Haskell projects
Type: lazy attribute set of (submodule)
Declared by:
perSystem.haskellProjects.<name>.packages
Additional packages to add to basePackages.
Local packages are added automatically (see config.defaults.packages):
You can also override the source for existing packages here.
Type: lazy attribute set of module
Default:
{ }
Declared by:
perSystem.haskellProjects.<name>.autoWire
List of flake output types to autowire.
Using an empty list will disable autowiring entirely,
enabling you to manually wire them using
config.haskellProjects.<name>.outputs.
Type: list of (one of “packages”, “checks”, “apps”, “devShells”)
Default:
[
"packages"
"checks"
"apps"
"devShells"
]
Declared by:
perSystem.haskellProjects.<name>.basePackages
Which Haskell package set / compiler to use.
You can effectively select the GHC version here.
To get the appropriate value, run:
nix-env -f "<nixpkgs>" -qaP -A haskell.compiler
And then, use that in pkgs.haskell.packages.ghc<version>
Type: lazy attribute set of raw value
Default:
pkgs.haskellPackages
Example:
"pkgs.haskell.packages.ghc924"
Declared by:
perSystem.haskellProjects.<name>.defaults.enable
Whether to enable haskell-flake’s default settings for this project.
Type: boolean
Default:
true
Declared by:
perSystem.haskellProjects.<name>.defaults.packages
Local packages scanned from projectRoot
Type: lazy attribute set of module
Default:
If you have a cabal.project file (under projectRoot), those packages
are automatically discovered. Otherwise, the top-level .cabal file is
used to discover the only local package.
haskell-flake currently supports a limited range of syntax for
cabal.project. Specifically it requires an explicit list of package
directories under the “packages” option.
Declared by:
perSystem.haskellProjects.<name>.defaults.devShell.tools
Build tools always included in devShell
Type: function that evaluates to a(n) lazy attribute set of (null or package)
Default:
<function>
Declared by:
perSystem.haskellProjects.<name>.defaults.projectModules.output
A haskell-flake project module that exports the packages and
settings options to the consuming flake. This enables the use of this
flake’s Haskell package as a dependency, re-using its overrides.
Type: module
Default: a generated module
Declared by:
perSystem.haskellProjects.<name>.defaults.settings.all
Default settings for all packages whose derivations are produced by haskell-flake.
For example,
{
# Inside haskellProjects.<name>
imports = [
inputs.moo.haskellFlakeProjectModules.output
];
packages = {
foo.source = "0.1";
bar.source = inputs.bar;
};
settings = {
baz.check = false;
};
}
and
...
build-depends:
moo
, foo
, bar
, baz
, qux
...
This will apply the settings to moo, foo, bar, baz. But not to qux.
Type: module
Default:
''
Nothing is changed by default.
''
Declared by:
perSystem.haskellProjects.<name>.defaults.settings.defined
Default settings for all the packages defined using haskell-flake.
For example,
{
# Inside haskellProjects.<name>
imports = [
inputs.moo.haskellFlakeProjectModules.output
];
packages = {
foo.source = "0.1";
bar.source = inputs.bar;
};
settings = {
baz.check = false;
};
}
and
...
build-depends:
moo
, foo
, bar
, baz
, qux
...
This will apply the settings to moo and packages in current project. But not to foo, bar, baz and qux.
Type: module
Default:
''
Speed up builds by disabling haddock and library profiling. Also ensures
release-worthiness.
This uses `local.toDefinedProject` option to determine which packages to
override. Thus, it applies to both local packages as well as
transitively imported packags that are local to that flake (managed by
haskell-flake). The goal being to use the same configuration
consistently for all packages using haskell-flake.
''
Declared by:
perSystem.haskellProjects.<name>.defaults.settings.local
Default settings for packages local to the current project.
Type: module
Default:
{ }
Declared by:
perSystem.haskellProjects.<name>.devShell
Development shell configuration
Type: submodule
Default:
{ }
Declared by:
perSystem.haskellProjects.<name>.devShell.enable
Whether to enable a development shell for the project.
Type: boolean
Default:
true
Declared by:
perSystem.haskellProjects.<name>.devShell.benchmark
Whether to include benchmark dependencies in the development shell.
The value of this option will set the corresponding doBenchmark flag in the
shellFor derivation.
Type: boolean
Default:
false
Declared by:
perSystem.haskellProjects.<name>.devShell.extraLibraries
Extra Haskell libraries available in the shell’s environment.
These can be used in the shell’s runghc and ghci for instance.
The argument is the Haskell package set.
The return type is an attribute set for overridability and syntax, as only the values are used.
Type: null or (function that evaluates to a(n) lazy attribute set of (null or package))
Default:
null
Example:
hp: { inherit (hp) releaser; }
Declared by:
perSystem.haskellProjects.<name>.devShell.hlsCheck
A check to make sure that your IDE will work.
Type: submodule
Default:
{ }
Declared by:
perSystem.haskellProjects.<name>.devShell.hlsCheck.enable
Whether to enable a flake check to verify that HLS works.
This is equivalent to nix develop -i -c haskell-language-server.
Note that, HLS will try to access the network through Cabal (see https://github.com/haskell/haskell-language-server/issues/3128), therefore sandboxing must be disabled when evaluating this check.
Type: boolean
Default:
false
Declared by:
perSystem.haskellProjects.<name>.devShell.hlsCheck.drv
The hlsCheck derivation generated for this project.
Type: package (read only)
Declared by:
perSystem.haskellProjects.<name>.devShell.hoogle
Whether to include Hoogle in the development shell.
The value of this option will set the corresponding withHoogle flag in the
shellFor derivation.
Type: boolean
Default:
true
Declared by:
perSystem.haskellProjects.<name>.devShell.mkShellArgs
Extra arguments to pass to pkgs.mkShell.
Type: lazy attribute set of raw value
Default:
{ }
Example:
''
{
shellHook = \'\'
# Re-generate .cabal files so HLS will work (per hie.yaml)
''${pkgs.findutils}/bin/find -name package.yaml -exec hpack {} \;
\'\';
};
''
Declared by:
perSystem.haskellProjects.<name>.devShell.tools
Build tools for developing the Haskell project.
These tools are merged with the haskell-flake defaults defined in the
defaults.devShell.tools option. Set the value to null to remove
that default tool.
Type: function that evaluates to a(n) lazy attribute set of (null or package)
Default:
<function>
Declared by:
perSystem.haskellProjects.<name>.otherOverlays
Extra overlays to apply.
Normally, you would only use packages.* and settings.* (which
translate to overlays), but you can use this option if you want control
over the final overlay.
Type: list of A Haskell overlay function taking ‘self’ and ‘super’ args.
Default:
[ ]
Declared by:
perSystem.haskellProjects.<name>.outputs
The flake outputs generated for this project.
This is an internal option, not meant to be set by the user.
Type: submodule
Declared by:
- haskell-flake/nix/modules/project/hls-check.nix
- haskell-flake/nix/modules/project/outputs.nix
- haskell-flake/nix/modules/project/devshell.nix
perSystem.haskellProjects.<name>.outputs.packages
Package information for all local packages. Contains the following keys:
package: The Haskell package derivationexes: Attrset of executables found in the .cabal file
Type: lazy attribute set of (submodule) (read only)
Declared by:
perSystem.haskellProjects.<name>.outputs.packages.<name>.package
The local package derivation.
Type: package
Declared by:
perSystem.haskellProjects.<name>.outputs.packages.<name>.exes
Attrset of executables from .cabal file.
If the associated Haskell project has a separate bin output
(cf. enableSeparateBinOutput), then this exe will refer
only to the bin output.
NOTE: Evaluating up to this option will involve IFD.
Type: lazy attribute set of (submodule)
Declared by:
perSystem.haskellProjects.<name>.outputs.packages.<name>.exes.<name>.meta
Metadata information about the app. Standardized in Nix at https://github.com/NixOS/nix/pull/11297.
Note: nix flake check is only aware of the description attribute in meta.
Type: lazy attribute set of raw value
Default:
{ }
Declared by:
perSystem.haskellProjects.<name>.outputs.packages.<name>.exes.<name>.program
A path to an executable or a derivation with meta.mainProgram.
Type: string or package convertible to it
Declared by:
perSystem.haskellProjects.<name>.outputs.packages.<name>.exes.<name>.type
A type tag for apps consumers.
Type: value “app” (singular enum)
Default:
"app"
Declared by:
perSystem.haskellProjects.<name>.outputs.apps
Flake apps for each Cabal executable in the project.
Type: lazy attribute set of (submodule) (read only)
Declared by:
perSystem.haskellProjects.<name>.outputs.apps.<name>.meta
Metadata information about the app. Standardized in Nix at https://github.com/NixOS/nix/pull/11297.
Note: nix flake check is only aware of the description attribute in meta.
Type: lazy attribute set of raw value
Default:
{ }
Declared by:
perSystem.haskellProjects.<name>.outputs.apps.<name>.program
A path to an executable or a derivation with meta.mainProgram.
Type: string or package convertible to it
Declared by:
perSystem.haskellProjects.<name>.outputs.apps.<name>.type
A type tag for apps consumers.
Type: value “app” (singular enum)
Default:
"app"
Declared by:
perSystem.haskellProjects.<name>.outputs.checks
The flake checks generated for this project.
Type: lazy attribute set of package (read only)
Declared by:
perSystem.haskellProjects.<name>.outputs.devShell
The development shell derivation generated for this project.
Type: package (read only)
Declared by:
perSystem.haskellProjects.<name>.outputs.finalPackages
The final Haskell package set including local packages and any
overrides, on top of basePackages.
Type: lazy attribute set of raw value (read only)
Declared by:
perSystem.haskellProjects.<name>.projectFlakeName
A descriptive name for the flake in which this project resides.
If unspecified, the Nix store path’s basename will be used.
Type: null or string
Default:
null
Declared by:
perSystem.haskellProjects.<name>.projectRoot
Path to the root of the project directory.
Chaning this affects certain functionality, like where to look for the ‘cabal.project’ file.
Type: absolute path
Default:
"Top-level directory of the flake"
Declared by:
perSystem.haskellProjects.<name>.settings
Overrides for packages in basePackages and packages.
Attr values are submodules that take the following arguments:
name: Package namepackage: The reference to the package inpackagesoption if it exists, null otherwise.self/super: The ‘self’ and ‘super’ (aka. ‘final’ and ‘prev’) used in the Haskell overlay.pkgs: Nixpkgs instance of the module user (import’er).
Default settings are defined in project.config.defaults.settings which can be overriden.
Type: lazy attribute set of module
Default:
{ }
Declared by: