haskellPackages.{ghcWithPackages, ghcWithHoogle}: make overrideable

This is achieved by passing the entire package set to the respective
wrappers and passing the select function as a second attribute. Together
with the new support for callPackage-ing functions this allows for
things like `ghcWithPackages.override { useLLVM = true; } (p: [ … ])`.

To make this possible for `ghcWithHoogle` as well, we need to make the
wrapper a bit more bespoke and inline the hoogle feature as well. The
hoogle wrapper, however, can remain separate and is exposed as
`hoogleWithPackages` additionally, as it can also serve standalone use.
`hoogleLocal` is kept for backwards compatibility (including the old,
suboptimal API), but will inform users about the better alternative via
a warning.

1 files changed, 39 insertions, 13 deletions

diff --git a/pkgs/development/haskell-modules/make-package-set.nix b/pkgs/development/haskell-modules/make-package-set.nix
index 98204198250..e9ce4f12705 100644
--- a/pkgs/development/haskell-modules/make-package-set.nix
+++ b/pkgs/development/haskell-modules/make-package-set.nix
@@ -120,11 +120,6 @@ let
   defaultScope = mkScope self;
   callPackage = drv: args: callPackageWithScope defaultScope drv args;
 
-  withPackages = packages: buildPackages.callPackage ./with-packages-wrapper.nix {
-    inherit (self) ghc llvmPackages;
-    inherit packages;
-  };
-
   # Use cabal2nix to create a default.nix for the package sources found at 'src'.
   haskellSrc2nix = { name, src, sha256 ? null, extraCabal2nixOptions ? "" }:
     let
@@ -269,22 +264,53 @@ in package-set { inherit pkgs lib callPackage; } self // {
            then (modifier drv).envFunc {inherit withHoogle;}
            else modifier drv;
 
-    ghcWithPackages = selectFrom: withPackages (selectFrom self);
+    # 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 = self.callPackage ./with-packages-wrapper.nix {
+      haskellPackages = self;
+    };
+
 
     # 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'
-    ghcWithHoogle = selectFrom:
-      let
-        packages = selectFrom self;
-        hoogle = callPackage ./hoogle.nix {
-          inherit packages;
-        };
-      in withPackages (packages ++ [ hoogle ]);
+    hoogleWithPackages = self.callPackage ./hoogle.nix {
+      haskellPackages = self;
+    };
+    hoogleLocal =
+      { packages ? [] }:
+      lib.warn "hoogleLocal is deprecated, use hoogleWithPackages instead" (
+        self.hoogleWithPackages (_: packages)
+      );
+    # This is like a combination of ghcWithPackages and hoogleWithPackages.
+    # It provides a derivation containing both GHC and Hoogle with an index of
+    # the given Haskell package database.
+    #
+    # Example:
+    #   $ nix-shell -p 'haskellPackages.ghcWithHoogle (hpkgs: [ hpkgs.conduit hpkgs.lens ])'
+    #
+    # ghcWithHoogle :: (HaskellPkgSet -> [ HaskellPkg ]) -> Derivation
+    ghcWithHoogle = self.ghcWithPackages.override {
+      withHoogle = true;
+    };
 
     # Returns a derivation whose environment contains a GHC with only
     # the dependencies of packages listed in `packages`, not the