Commit 8e803f2f authored by Profpatsch's avatar Profpatsch
Browse files

haskell-language-server: keep only formatters the user wants 

This introduces a list of `supportedFormatters` that are the ones that
should be compiled into hls. Removes a nontrivial amount of transitive
dependencies if only one formatter is used in a project.
parent 529cbf1a

pkgs/development/tools/haskell/haskell-language-server/withWrapper.nix

+76 −3
Original line number Diff line number Diff line
@@ -13,8 +13,13 @@ 
# Whether to build hls with the dynamic run-time system.

# See https://haskell-language-server.readthedocs.io/en/latest/troubleshooting.html#static-binaries for more information.

, dynamic ? true



# which formatters are supported. An empty list means “all”.

, supportedFormatters ? [ ]

}:



# make sure the user only sets GHC versions that actually exist

assert supportedGhcVersions != [];

assert

  lib.asserts.assertEachOneOf

    "supportedGhcVersions"
@@ -24,6 +29,47 @@ assert 
      (lib.filter (lib.hasPrefix "ghc"))

      (map (lib.removePrefix "ghc"))

    ]);



let

  # A mapping from formatter name to

  # - cabal flag to disable

  # - formatter-specific packages that can be stripped from the build of hls if it is disabled

  knownFormatters = {

    ormolu = {

      cabalFlag = "ormolu";

      packages = [

        "hls-ormolu-plugin"

      ];

    };

    fourmolu = {

      cabalFlag = "fourmolu";

      packages = [

        "hls-fourmolu-plugin"

      ];

    };

    floskell = {

      cabalFlag = "floskell";

      packages = [

        "hls-floskell-plugin"

      ];

    };

    stylish-haskell = {

      cabalFlag = "stylishhaskell";

      packages = [

        "hls-stylish-haskell-plugin"

      ];

    };

  };



in



# make sure any formatter that is set is actually supported by us

assert

  lib.asserts.assertEachOneOf

    "supportedFormatters"

    supportedFormatters

    (lib.attrNames knownFormatters);



#

# The recommended way to override this package is

#
@@ -41,6 +87,34 @@ let 


  getPackages = version: haskell.packages."ghc${version}";



  # Given the list of `supportedFormatters`, remove every formatter that we know of (knownFormatters)

  # by disabling the cabal flag and also removing the formatter libraries.

  removeUnnecessaryFormatters =

    let

      # only formatters that were not requested

      unwanted = lib.pipe knownFormatters [

        (lib.filterAttrs (fmt: _: ! (lib.elem fmt supportedFormatters)))

        lib.attrsToList

      ];

      # all flags to disable

      flags = map (fmt: fmt.value.cabalFlag) unwanted;

      # all dependencies to remove from hls

      deps = lib.concatMap (fmt: fmt.value.packages) unwanted;



      # remove nulls from a list

      stripNulls = lib.filter (x: x != null);



      # remove all unwanted dependencies of formatters we don’t want

      stripDeps = overrideCabal (drv: {

        libraryHaskellDepends = lib.pipe (drv.libraryHaskellDepends or []) [

          # the existing list may contain nulls, so let’s strip them first

          stripNulls

          (lib.filter (dep: ! (lib.elem dep.pname deps)))

        ];

      });



    in drv: lib.pipe drv ([stripDeps] ++ map disableCabalFlag flags);



  tunedHls = hsPkgs:

    lib.pipe hsPkgs.haskell-language-server ([

      (haskell.lib.compose.overrideCabal (old: {
@@ -52,6 +126,7 @@ let 
        '';

      }))

      ((if dynamic then enableCabalFlag else disableCabalFlag) "dynamic")

      (if supportedFormatters != [] then removeUnnecessaryFormatters else lib.id)

    ]

    ++ lib.optionals (!dynamic) [

      justStaticExecutables
@@ -69,9 +144,7 @@ let 
        }/bin/haskell-language-server $out/bin/${x}")

      (targets version);



in

assert supportedGhcVersions != []; stdenv.mkDerivation

{

in stdenv.mkDerivation {

  pname = "haskell-language-server";

  version = haskellPackages.haskell-language-server.version;