path: root/pkgs/development/haskell-modules/make-package-set.nix

# This expression takes a file like `hackage-packages.nix` and constructs
# a full package set out of that.

{ # package-set used for build tools (all of nixpkgs)
  buildPackages

, # A haskell package set for Setup.hs, compiler plugins, and similar
  # build-time uses.
  buildHaskellPackages

, # package-set used for non-haskell dependencies (all of nixpkgs)
  pkgs

, # stdenv provides our build and host platforms
  stdenv

, # this module provides the list of known licenses and maintainers
  lib

  # needed for overrideCabal & packageSourceOverrides
, haskellLib

, # hashes for downloading Hackage packages
  # This is either a directory or a .tar.gz containing the cabal files and
  # hashes of Hackage as exemplified by this repository:
  # https://github.com/commercialhaskell/all-cabal-hashes/tree/hackage
  all-cabal-hashes

, # compiler to use
  ghc

, # A function that takes `{ pkgs, lib, callPackage }` as the first arg and
  # `self` as second, and returns a set of haskell packages
  package-set

, # The final, fully overridden package set usable with the nixpkgs fixpoint
  # overriding functionality
  extensible-self
}:

# return value: a function from self to the package set
self:

let
  inherit (stdenv) buildPlatform hostPlatform;

  inherit (lib) fix' extends makeOverridable;
  inherit (haskellLib) overrideCabal;

  mkDerivationImpl = pkgs.callPackage ./generic-builder.nix {
    inherit stdenv;
    nodejs = buildPackages.nodejs-slim;
    inherit (self) buildHaskellPackages ghc ghcWithHoogle ghcWithPackages;
    inherit (self.buildHaskellPackages) jailbreak-cabal;
    hscolour = overrideCabal (drv: {
      isLibrary = false;
      doHaddock = false;
      hyperlinkSource = false;      # Avoid depending on hscolour for this build.
      postFixup = "rm -rf $out/lib $out/share $out/nix-support";
    }) self.buildHaskellPackages.hscolour;
    cpphs = overrideCabal (drv: {
        isLibrary = false;
        postFixup = "rm -rf $out/lib $out/share $out/nix-support";
    }) (self.cpphs.overrideScope (self: super: {
      mkDerivation = drv: super.mkDerivation (drv // {
        enableSharedExecutables = false;
        enableSharedLibraries = false;
        doHaddock = false;
        useCpphs = false;
      });
    }));
  };

  mkDerivation = makeOverridable mkDerivationImpl;

  # manualArgs are the arguments that were explicitly passed to `callPackage`, like:
  #
  # callPackage foo { bar = null; };
  #
  # here `bar` is a manual argument.
  callPackageWithScope = scope: fn: manualArgs:
    let
      # this code is copied from callPackage in lib/customisation.nix
      #
      # we cannot use `callPackage` here because we want to call `makeOverridable`
      # on `drvScope` (we cannot add `overrideScope` after calling `callPackage` because then it is
      # lost on `.override`) but determine the auto-args based on `drv` (the problem here
      # is that nix has no way to "passthrough" args while preserving the reflection
      # info that callPackage uses to determine the arguments).
      drv = if lib.isFunction fn then fn else import fn;
      auto = builtins.intersectAttrs (lib.functionArgs drv) scope;

      # Converts a returned function to a functor attribute set if necessary
      ensureAttrs = v: if builtins.isFunction v then { __functor = _: v; } else v;

      # this wraps the `drv` function to add `scope` and `overrideScope` to the result.
      drvScope = allArgs: ensureAttrs (drv allArgs) // {
        inherit scope;
        overrideScope = f:
          let newScope = mkScope (fix' (extends f scope.__unfix__));
          # note that we have to be careful here: `allArgs` includes the auto-arguments that
          # weren't manually specified. If we would just pass `allArgs` to the recursive call here,
          # then we wouldn't look up any packages in the scope in the next interation, because it
          # appears as if all arguments were already manually passed, so the scope change would do
          # nothing.
          in callPackageWithScope newScope drv manualArgs;
      };
    in lib.makeOverridable drvScope (auto // manualArgs);

  mkScope = scope: let
      ps = pkgs.__splicedPackages;
      scopeSpliced = pkgs.splicePackages {
        pkgsBuildBuild = scope.buildHaskellPackages.buildHaskellPackages;
        pkgsBuildHost = scope.buildHaskellPackages;
        pkgsBuildTarget = {};
        pkgsHostHost = {};
        pkgsHostTarget = scope;
        pkgsTargetTarget = {};
      } // {
        # Don't splice these
        inherit (scope) ghc buildHaskellPackages;
      };
    in ps // ps.xorg // ps.gnome2 // { inherit stdenv; } // scopeSpliced;
  defaultScope = mkScope self;
  callPackage = drv: args: callPackageWithScope defaultScope drv args;

  # Use cabal2nix to create a default.nix for the package sources found at 'src'.
  haskellSrc2nix = { name, src, sha256 ? null, extraCabal2nixOptions ? "" }:
    let
      sha256Arg = if sha256 == null then "--sha256=" else ''--sha256="${sha256}"'';
    in buildPackages.runCommand "cabal2nix-${name}" {
      nativeBuildInputs = [ buildPackages.cabal2nix-unwrapped ];
      preferLocalBuild = true;
      allowSubstitutes = false;
      LANG = "en_US.UTF-8";
      LOCALE_ARCHIVE = pkgs.lib.optionalString (buildPlatform.libc == "glibc") "${buildPackages.glibcLocales}/lib/locale/locale-archive";
    } ''
      export HOME="$TMP"
      mkdir -p "$out"
      cabal2nix --compiler=${self.ghc.haskellCompilerName} --system=${hostPlatform.config} ${sha256Arg} "${src}" ${extraCabal2nixOptions} > "$out/default.nix"
    '';

  # Given a package name and version, e.g. name = "async", version = "2.2.4",
  # gives its cabal file and hashes (JSON file) as discovered from the
  # all-cabal-hashes value. If that's a directory, it will copy the relevant
  # files to $out; if it's a tarball, it will extract and move them to $out.
  all-cabal-hashes-component = name: version: buildPackages.runCommand "all-cabal-hashes-component-${name}-${version}" {} ''
    mkdir -p $out
    if [ -d ${all-cabal-hashes} ]
    then
      cp ${all-cabal-hashes}/${name}/${version}/${name}.json $out
      cp ${all-cabal-hashes}/${name}/${version}/${name}.cabal $out
    else
      tar --wildcards -xzvf ${all-cabal-hashes} \*/${name}/${version}/${name}.{json,cabal}
      mv */${name}/${version}/${name}.{json,cabal} $out
    fi
  '';

  hackage2nix = name: version: let component = all-cabal-hashes-component name version; in self.haskellSrc2nix {
    name   = "${name}-${version}";
    sha256 = ''$(sed -e 's/.*"SHA256":"//' -e 's/".*$//' "${component}/${name}.json")'';
    src    = "${component}/${name}.cabal";
  };

  # Adds a nix file derived from cabal2nix in the passthru of the derivation it
  # produces. This is useful to debug callHackage / callCabal2nix by looking at
  # the content of the nix file pointed by `cabal2nixDeriver`.
  # However, it does not keep a reference to that file, which may be garbage
  # collected, which may be an annoyance.
  callPackageKeepDeriver = src: args:
    overrideCabal (orig: {
      passthru = orig.passthru or {} // {
        # When using callCabal2nix or callHackage, it is often useful
        # to debug a failure by inspecting the Nix expression
        # generated by cabal2nix. This can be accessed via this
        # cabal2nixDeriver field.
        cabal2nixDeriver = src;
      };
    }) (self.callPackage src args);

in package-set { inherit pkgs lib callPackage; } self // {

    inherit mkDerivation callPackage haskellSrc2nix hackage2nix buildHaskellPackages;

    inherit (haskellLib) packageSourceOverrides;

    # callHackage :: Text -> Text -> AttrSet -> HaskellPackage
    #
    # e.g., while overriding a package set:
    #    '... foo = self.callHackage "foo" "1.5.3" {}; ...'
    callHackage = name: version: callPackageKeepDeriver (self.hackage2nix name version);

    # callHackageDirect
    #   :: { pkg :: Text, ver :: Text, sha256 :: Text }
    #   -> AttrSet
    #   -> HaskellPackage
    #
    # This function does not depend on all-cabal-hashes and therefore will work
    # for any version that has been released on hackage as opposed to only
    # versions released before whatever version of all-cabal-hashes you happen
    # to be currently using.
    callHackageDirect = {pkg, ver, sha256}:
      let pkgver = "${pkg}-${ver}";
      in self.callCabal2nix pkg (pkgs.fetchzip {
           url = "mirror://hackage/${pkgver}/${pkgver}.tar.gz";
           inherit sha256;
         });

    # Creates a Haskell package from a source package by calling cabal2nix on the source.
    callCabal2nixWithOptions = name: src: extraCabal2nixOptions: args:
      let
        filter = path: type:
                   pkgs.lib.hasSuffix ".cabal" path ||
                   baseNameOf path == "package.yaml";
        expr = self.haskellSrc2nix {
          inherit name extraCabal2nixOptions;
          src = if pkgs.lib.canCleanSource src
                  then pkgs.lib.cleanSourceWith { inherit src filter; }
                else src;
        };
      in overrideCabal (orig: {
           inherit src;
         }) (callPackageKeepDeriver expr args);

    callCabal2nix = name: src: args: self.callCabal2nixWithOptions name src "" args;

    # : { root : Path
    #   , name : Defaulted String
    #   , source-overrides : Defaulted (Either Path VersionNumber)
    #   , overrides : Defaulted (HaskellPackageOverrideSet)
    #   , modifier : Defaulted
    #   , returnShellEnv : Defaulted
    #   , withHoogle : Defaulted
    #   , cabal2nixOptions : Defaulted
    #   } -> NixShellAwareDerivation
    #
    # Given a path to a haskell package directory, an optional package name
    # which defaults to the base name of the path, an optional set of source
    # overrides as appropriate for the 'packageSourceOverrides' function, an
    # optional set of arbitrary overrides, and an optional haskell package
    # modifier, return a derivation appropriate for nix-build or nix-shell to
    # build that package.
    #
    # If 'returnShellEnv' is true this returns a derivation which will give you
    # an environment suitable for developing the listed packages with an
    # incremental tool like cabal-install.
    #
    # If 'withHoogle' is true (the default if a shell environment is requested)
    # then 'ghcWithHoogle' is used to generate the derivation (instead of
    # 'ghcWithPackages'), see the documentation there for more information.
    #
    # 'cabal2nixOptions' can contain extra command line arguments to pass to
    # 'cabal2nix' when generating the package derivation, for example setting
    # a cabal flag with '--flag=myflag'.
    developPackage =
      { root
      , name ? lib.optionalString (builtins.typeOf root == "path") (builtins.baseNameOf root)
      , source-overrides ? {}
      , overrides ? self: super: {}
      , modifier ? drv: drv
      , returnShellEnv ? pkgs.lib.inNixShell
      , withHoogle ? returnShellEnv
      , cabal2nixOptions ? "" }:
      let drv =
        (extensible-self.extend
           (pkgs.lib.composeExtensions
              (self.packageSourceOverrides source-overrides)
              overrides))
        .callCabal2nixWithOptions name root cabal2nixOptions {};
      in if returnShellEnv
           then (modifier drv).envFunc {inherit withHoogle;}
           else modifier drv;

    # This can be used to easily create a derivation containing GHC and the specified set of Haskell packages.
    #
    # Example:
    #   $ nix-shell -p 'haskellPackages.ghcWithPackages (hpkgs: [ hpkgs.mtl hpkgs.lens ])'
    #   $ ghci    # in the nix-shell
    #   Prelude > import Control.Lens
    #
    # GHC is setup with a package database with all the specified Haskell packages.
    #
    # ghcWithPackages :: (HaskellPkgSet -> [ HaskellPkg ]) -> Derivation
    ghcWithPackages = buildHaskellPackages.callPackage ./with-packages-wrapper.nix {
      haskellPackages = self;
      inherit (self) hoogleWithPackages;
    };


    # Put 'hoogle' into the derivation's PATH with a database containing all
    # the package's dependencies; run 'hoogle server --local' in a shell to
    # host a search engine for the dependencies.
    #
    # Example usage:
    #  $ nix-shell -p 'haskellPackages.hoogleWithPackages (p: [ p.mtl p.lens ])'
    #  [nix-shell] $ hoogle server
    #
    # hoogleWithPackages :: (HaskellPkgSet -> [ HaskellPkg ]) -> Derivation
    #
    # To reload the Hoogle server automatically on .cabal file changes try
    # this:
    # echo *.cabal | entr -r -- nix-shell --run 'hoogle server --local'
    hoogleWithPackages = self.callPackage ./hoogle.nix {
      haskellPackage