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haskellPackages.shellFor: improve documentation
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(cdep)illabout
Peter Simons
parent
0fa596936b
commit
17eee57642
@ -258,6 +258,7 @@ in package-set { inherit pkgs stdenv callPackage; } self // {
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# packages themselves. Using nix-shell on this derivation will
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# give you an environment suitable for developing the listed
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# packages with an incremental tool like cabal-install.
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#
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# In addition to the "packages" arg and "withHoogle" arg, anything that
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# can be passed into stdenv.mkDerivation can be included in the input attrset
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#
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@ -274,7 +275,7 @@ in package-set { inherit pkgs stdenv callPackage; } self // {
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# (import ./.).shellFor {
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# packages = p: [p.frontend p.backend p.common];
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# withHoogle = true;
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# buildInputs = [ pkgs.python ];
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# buildInputs = [ pkgs.python pkgs.cabal-install ];
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# }
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#
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# -- cabal.project
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@ -285,38 +286,143 @@ in package-set { inherit pkgs stdenv callPackage; } self // {
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#
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# bash$ nix-shell --run "cabal new-build all"
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# bash$ nix-shell --run "python"
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shellFor = { packages, withHoogle ? false, ... } @ args:
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shellFor =
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{ # Packages to create this development shell for. These are usually
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# your local packages.
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packages
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, # Whether or not to generated a Hoogle database for all the
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# dependencies.
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withHoogle ? false
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, ...
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} @ args:
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let
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combinedPackageFor = packages:
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let
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selected = packages self;
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# A list of the packages we want to build a development shell for.
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#
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# This is a list of Haskell package derivations.
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selected = packages self;
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pname = if pkgs.lib.length selected == 1
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then (pkgs.lib.head selected).name
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else "packages";
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# This is a list of attribute sets, where the each attribute set
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# corresponds to the build inputs one of the packages input to shellFor.
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#
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# Each attribute has keys like buildDepends, executableHaskellDepends,
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# testPkgconfigDepends, etc. The values for the keys of the attribute
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# set are lists of dependencies.
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#
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# Example:
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# cabalDepsForSelected
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# => [
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# # This may be the attribute set corresponding to the `backend`
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# # package in the example above.
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# { buildDepends = [ gcc ... ];
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# libraryHaskellDepends = [ lens conduit ... ];
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# ...
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# }
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# # This may be the attribute set corresponding to the `common`
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# # package in the example above.
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# { testHaskellDepends = [ tasty hspec ... ];
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# libraryHaskellDepends = [ lens aeson ];
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# benchmarkHaskellDepends = [ criterion ... ];
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# ...
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# }
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# ...
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# ]
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cabalDepsForSelected = map (p: p.getCabalDeps) selected;
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# If `packages = [ a b ]` and `a` depends on `b`, don't build `b`,
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# because cabal will end up ignoring that built version, assuming
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# new-style commands.
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combinedPackages = pkgs.lib.filter
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(input: pkgs.lib.all (p: input.outPath or null != p.outPath) selected);
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# A predicate that takes a derivation as input, and tests whether it is
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# the same as any of the `selected` packages.
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#
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# Returns true if the input derivation is not in the list of `selected`
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# packages.
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#
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# isNotSelected :: Derivation -> Bool
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#
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# Example:
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#
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# isNotSelected common [ frontend backend common ]
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# => false
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#
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# isNotSelected lens [ frontend backend common ]
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# => true
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isNotSelected = input: pkgs.lib.all (p: input.outPath or null != p.outPath) selected;
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# Returns an attrset containing a combined list packages' inputs for each
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# stage of the build process
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packageInputs = pkgs.lib.zipAttrsWith
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(_: pkgs.lib.concatMap combinedPackages)
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(map (p: p.getCabalDeps) selected);
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# A function that takes a list of list of derivations, filters out all
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# the `selected` packages from each list, and concats the results.
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#
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# zipperCombinedPkgs :: [[Derivation]] -> [Derivation]
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#
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# Example:
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# zipperCombinedPkgs [ [ lens conduit ] [ aeson frontend ] ]
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# => [ lens conduit aeson ]
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#
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# Note: The reason this isn't just the function `pkgs.lib.concat` is
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# that we need to be careful to remove dependencies that are in the
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# `selected` packages.
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#
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# For instance, in the above example, if `common` is a dependency of
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# `backend`, then zipperCombinedPkgs needs to be careful to filter out
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# `common`, because cabal will end up ignoring that built version,
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# assuming new-style commands.
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zipperCombinedPkgs = vals:
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pkgs.lib.concatMap
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(drvList: pkgs.lib.filter isNotSelected drvList)
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vals;
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genericBuilderArgs = {
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inherit pname;
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version = "0";
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license = null;
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} // packageInputs;
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# Zip `cabalDepsForSelected` into a single attribute list, combining
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# the derivations in all the individual attributes.
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#
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# Example:
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# packageInputs
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# => # Assuming the value of cabalDepsForSelected is the same as
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# # the example in cabalDepsForSelected:
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# { buildDepends = [ gcc ... ];
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# libraryHaskellDepends = [ lens conduit aeson ... ];
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# testHaskellDepends = [ tasty hspec ... ];
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# benchmarkHaskellDepends = [ criterion ... ];
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# ...
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# }
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#
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# See the Note in `zipperCombinedPkgs` for what gets filtered out from
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# each of these dependency lists.
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packageInputs =
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pkgs.lib.zipAttrsWith (_name: zipperCombinedPkgs) cabalDepsForSelected;
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in self.mkDerivation genericBuilderArgs;
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# A attribute set to pass to `haskellPackages.mkDerivation`.
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#
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# The important thing to note here is that all the fields from
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# packageInputs are set correctly.
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genericBuilderArgs = {
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pname =
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if pkgs.lib.length selected == 1
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then (pkgs.lib.head selected).name
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else "packages";
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version = "0";
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license = null;
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}
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// packageInputs;
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# This is a pseudo Haskell package derivation that contains all the
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# dependencies for the packages in `selected`.
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#
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# This is a derivation created with `haskellPackages.mkDerivation`.
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#
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# pkgWithCombinedDeps :: HaskellDerivation
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pkgWithCombinedDeps = self.mkDerivation genericBuilderArgs;
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# The derivation returned from `envFunc` for `pkgWithCombinedDeps`.
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#
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# This is a derivation that can be run with `nix-shell`. It provides a
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# GHC with a package database with all the dependencies of our
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# `selected` packages.
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#
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# This is a derivation created with `stdenv.mkDerivation` (not
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# `haskellPackages.mkDerivation`).
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#
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# pkgWithCombinedDepsDevDrv :: Derivation
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pkgWithCombinedDepsDevDrv = pkgWithCombinedDeps.envFunc { inherit withHoogle; };
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mkDerivationArgs = builtins.removeAttrs args [ "packages" "withHoogle" ];
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in ((combinedPackageFor packages).envFunc { inherit withHoogle; }).overrideAttrs (old: mkDerivationArgs // {
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in pkgWithCombinedDepsDevDrv.overrideAttrs (old: mkDerivationArgs // {
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nativeBuildInputs = old.nativeBuildInputs ++ mkDerivationArgs.nativeBuildInputs or [];
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buildInputs = old.buildInputs ++ mkDerivationArgs.buildInputs or [];
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});
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