Shell for plus

builder/make-config-files.nix

@@ -1,16 +1,21 @@
 { stdenv, lib, haskellLib, ghc, nonReinstallablePkgs, runCommand }:
 
+with builtins; with lib;
 let
   flagsAndConfig = field: xs: lib.optionalString (xs != []) ''
     echo ${lib.concatStringsSep " " (map (x: "--${field}=${x}") xs)} >> $out/configure-flags
     echo "${field}: ${lib.concatStringsSep " " xs}" >> $out/cabal.config
   '';
 
-  flatDepends = component:
+  ## packageHasLib :: Package -> Bool
+  packageHasLib = p: hasAttr "library" p.components;
+  ## flatLibDepends :: Component -> [Package]
+  flatLibDepends =
+    component:
     let
-      makePairs = map (p: rec { key="${val}"; val=(p.components.library or p); });
+      makePairs = map (p: rec { key="${val.name}"; val=p.components.library; });
       closure = builtins.genericClosure {
-        startSet = makePairs component.depends;
+        startSet = makePairs (filter packageHasLib component.depends);
         operator = {val,...}: makePairs val.config.depends;
       };
     in map ({val,...}: val) closure;
@@ -58,7 +63,7 @@ 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)}
+    '') (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"]}
@@ -69,15 +74,17 @@ in { identifier, component, fullName, flags ? {} }:
     cat > $out/ghc-environment <<EOF
     package-db $out/package.conf.d
     EOF
-    ${lib.concatMapStringsSep "\n" (p: envDep "--package-db ${p.components.library or p}/package.conf.d" p.identifier.name) component.depends}
+    ${lib.concatMapStringsSep "\n" (p: envDep "--package-db ${p.components.library}/package.conf.d" p.identifier.name)
+                                   (filter packageHasLib component.depends)}
     ${lib.concatMapStringsSep "\n" (envDep "") (lib.remove "ghc" nonReinstallablePkgs)}
 
   '' + lib.optionalString component.doExactConfig ''
     echo "--exact-configuration" >> $out/configure-flags
     echo "allow-newer: ${identifier.name}:*" >> $out/cabal.config
     echo "allow-older: ${identifier.name}:*" >> $out/cabal.config
 
-    ${lib.concatMapStringsSep "\n" (p: exactDep "--package-db ${p.components.library}/package.conf.d" p.identifier.name) component.depends}
+    ${lib.concatMapStringsSep "\n" (p: exactDep "--package-db ${p.components.library}/package.conf.d" p.identifier.name)
+                                   (filter packageHasLib component.depends)}
     ${lib.concatMapStringsSep "\n" (exactDep "") nonReinstallablePkgs}
 
   ''

builder/shell-for.nix

@@ -1,6 +1,6 @@
 { buildPackages, lib, stdenv, ghcForComponent, makeConfigFiles, hsPkgs }:
 
-{ packages, withHoogle ? true } @ args:
+{ packages, buildInputs ? [], withHoogle ? true } @ args:
 
 let
   selected = packages hsPkgs;
@@ -29,7 +29,7 @@ in
   stdenv.mkDerivation (mkDrvArgs // {
     name = mkDrvArgs.name or name;
 
-    buildInputs = systemInputs ++ mkDrvArgs.buildInputs or [];
+    buildInputs = buildInputs ++ systemInputs ++ mkDrvArgs.buildInputs or [];
     nativeBuildInputs = [ ghcEnv ] ++ nativeBuildInputs ++ mkDrvArgs.nativeBuildInputs or [];
     phases = ["installPhase"];
     installPhase = "echo $nativeBuildInputs $buildInputs > $out";