Build Hoogle index for development shell

builder/default.nix

@@ -20,6 +20,13 @@ let
     inherit ghc haskellLib nonReinstallablePkgs;
   };
 
+  hoogleLocal = let
+    nixpkgsHoogleLocal = import (pkgs.path + /pkgs/development/haskell-modules/hoogle.nix);
+  in { packages ? [], hoogle ? pkgs.haskellPackages.hoogle }:
+    haskellLib.weakCallPackage pkgs nixpkgsHoogleLocal {
+      inherit packages hoogle;
+    };
+
 in {
   # Build a Haskell package from its config.
   # TODO: this pkgs is the adjusted pkgs, but pkgs.pkgs is unadjusted
@@ -29,7 +36,7 @@ in {
 
   # Same as haskellPackages.shellFor in nixpkgs.
   shellFor = haskellLib.weakCallPackage pkgs ./shell-for.nix {
-    inherit hsPkgs ghcForComponent makeConfigFiles;
+    inherit hsPkgs ghcForComponent makeConfigFiles hoogleLocal haskellLib;
     inherit (buildPackages) glibcLocales;
   };
 }

builder/make-config-files.nix

@@ -6,15 +6,6 @@ let
     echo "${field}: ${lib.concatStringsSep " " xs}" >> $out/cabal.config
   '';
 
-  flatDepends = component:
-    let
-      makePairs = map (p: rec { key="${val}"; val=(p.components.library or p); });
-      closure = builtins.genericClosure {
-        startSet = makePairs component.depends;
-        operator = {val,...}: makePairs val.config.depends;
-      };
-    in map ({val,...}: val) closure;
-
   exactDep = pdbArg: p: ''
     if id=$(target-pkg ${pdbArg} field ${p} id --simple-output); then
       echo "--dependency=${p}=$id" >> $out/configure-flags
@@ -58,7 +49,7 @@ in { identifier, component, fullName, flags ? {} }:
 
     ${lib.concatMapStringsSep "\n" (p: ''
       target-pkg --package-db ${p}/package.conf.d dump | target-pkg --force --package-db $out/package.conf.d register -
-    '') (flatDepends component)}
+    '') (haskellLib.flatLibDepends component)}
 
     # Note: we pass `clear` first to ensure that we never consult the implicit global package db.
     ${flagsAndConfig "package-db" ["clear" "$out/package.conf.d"]}

builder/shell-for.nix

@@ -1,4 +1,4 @@
-{ lib, stdenv, glibcLocales, pkgconfig, ghcForComponent, makeConfigFiles, hsPkgs }:
+{ lib, stdenv, glibcLocales, pkgconfig, ghcForComponent, makeConfigFiles, hsPkgs, hoogleLocal, haskellLib }:
 
 { packages, withHoogle ? true, ... } @ args:
 
@@ -23,27 +23,47 @@ let
   nativeBuildInputs = lib.concatMap (p: p.components.all.executableToolDepends) selected;
 
   # Set up a "dummy" component to use with ghcForComponent.
+  component = {
+    depends = packageInputs;
+    libs = [];
+    frameworks = [];
+    doExactConfig = false;
+  };
   configFiles = makeConfigFiles {
     fullName = args.name or name;
     identifier.name = name;
-    component = {
-      depends = packageInputs;
-      libs = [];
-      frameworks = [];
-      doExactConfig = false;
-    };
+    inherit component;
   };
   ghcEnv = ghcForComponent {
     componentName = name;
     inherit configFiles;
   };
+
+  hoogleIndex = let
+    # Get the doc package for a component, and add attributes that
+    # hoogle.nix expects.
+    docPackage = p: lib.getOutput "doc" p // {
+      pname = p.identifier.name;
+      haddockDir = lib.const p.haddockDir;
+    };
+  in hoogleLocal {
+    packages = map docPackage (haskellLib.flatLibDepends component);
+
+    # Need to add hoogle to hsPkgs.
+    # inherit (hsPkgs) hoogle;
+  };
+
   mkDrvArgs = builtins.removeAttrs args ["packages" "withHoogle"];
 in
   stdenv.mkDerivation (mkDrvArgs // {
     name = mkDrvArgs.name or name;
 
-    buildInputs = systemInputs ++ mkDrvArgs.buildInputs or [];
-    nativeBuildInputs = [ ghcEnv ] ++ nativeBuildInputs ++ mkDrvArgs.nativeBuildInputs or [];
+    buildInputs = systemInputs
+      ++ mkDrvArgs.buildInputs or []
+      ++ lib.optional withHoogle hoogleIndex;
+    nativeBuildInputs = [ ghcEnv ]
+      ++ nativeBuildInputs
+      ++ mkDrvArgs.nativeBuildInputs or [];
     phases = ["installPhase"];
     installPhase = "echo $nativeBuildInputs $buildInputs > $out";
     LANG = "en_US.UTF-8";

lib/default.nix

@@ -80,4 +80,16 @@ with haskellLib;
     let f' = if lib.isFunction f then f else import f;
         args' = (builtins.intersectAttrs (builtins.functionArgs f') scope) // args;
     in f' args';
+
+  # Collect all (transitive) Haskell library dependencies of a
+  # component.
+  ## flatLibDepends :: Component -> [Package]
+  flatLibDepends = component:
+    let
+      makePairs = map (p: rec { key="${val}"; val=(p.components.library or p); });
+      closure = builtins.genericClosure {
+        startSet = makePairs component.depends;
+        operator = {val,...}: makePairs val.config.depends;
+      };
+    in map ({val,...}: val) closure;
 }

test/tests.sh

@@ -61,4 +61,11 @@ nix-shell $NIX_BUILD_ARGS \
     --run 'cd shell-for && cabal new-build all'
 echo >& 2
 
+printf "*** Checking shellFor has a working hoogle index...\n" >& 2
+nix-shell $NIX_BUILD_ARGS \
+    --pure ./default.nix \
+    -A shell-for.env \
+    --run 'hoogle ConduitT | grep Data.Conduit'
+echo >& 2
+
 printf "\n*** Finished successfully\n" >& 2