Add nix module system with project helper and reflex-dom dep

- default.nix: top-level entry point delegating to nix/
- nix/default.nix: project function wrapping nix-haskell with obelisk
  module pre-imported
- nix/module.nix: declare obelisk.static and obelisk.frontend.js as
  NixOS module options (replacing function arguments)
- nix/lib.nix: rename ghcjsFrontend to frontendJs, add reflex-dom and
  reflex-dom-core as source-repository-packages
- Add reflex-dom and nix-haskell submodules

Author: ymeister

.gitmodules

@@ -0,0 +1,6 @@
+[submodule "deps/nix-haskell"]
+	path = deps/nix-haskell
+	url = git@github.com:reflex-frp/nix-haskell.git
+[submodule "deps/reflex-dom"]
+	path = deps/reflex-dom
+	url = https://github.com/ymeister/reflex-dom.git

default.nix

@@ -0,0 +1 @@
+import ./nix

deps/nix-haskell

@@ -0,0 +1 @@
+../deps/nix-haskell/docs/modules.man

deps/reflex-dom

@@ -0,0 +1 @@
+../deps/nix-haskell/docs/modules.md

docs/modules.man

@@ -0,0 +1,19 @@
+{ system }:
+
+let lib = import ./lib.nix { inherit system; };
+
+    nix-haskell = import ../deps/nix-haskell { inherit system; };
+
+    module = import ./module.nix;
+
+in lib // {
+  inherit module;
+  inherit (lib) extraCabalProject;
+
+  project = userModule: (nix-haskell {
+    imports = [
+      module
+      userModule
+    ];
+  }).haskell-nix.project;
+}

docs/modules.md

@@ -0,0 +1,128 @@
+{ system }:
+
+let src = ../.;
+
+    nix-haskell = import ../deps/nix-haskell { inherit system; };
+
+    # Standalone project built only to produce the manifest generator executable.
+    obelisk-asset-manifest = nix-haskell {
+      name = "obelisk-asset-manifest";
+      src = src + "/lib/asset/manifest";
+    };
+
+    obelisk-asset-manifest-generate =
+      "${obelisk-asset-manifest.haskell-nix.project.hsPkgs.obelisk-asset-manifest.components.exes.obelisk-asset-manifest-generate}/bin/obelisk-asset-manifest-generate";
+
+    # Keep only overrides whose package name exists in the project,
+    # so overrides for absent packages are silently skipped.
+    mkOptionalPackages = { config, lib }:
+      lib.filterAttrs (name: _: config.packages ? ${name});
+
+    # Generate the Obelisk.Generated.Static Haskell module from static assets.
+    obelisk-generated-static-manifest = static:
+      obelisk-asset-manifest.nixpkgs.runCommand "obelisk-generated-static" {
+        LANG = "en_US.UTF-8";
+        LOCALE_ARCHIVE = "${obelisk-asset-manifest.nixpkgs.glibcLocales}/lib/locale/locale-archive";
+      } ''
+        ${obelisk-asset-manifest-generate} ${static} $out obelisk-generated-static Obelisk.Generated.Static $out/files
+        sed -i -e 's/GHC\.Internal\.Types/GHC.Types/g' $out/src/Obelisk/Generated/Static.hs
+      '';
+
+in {
+  inherit src obelisk-asset-manifest obelisk-asset-manifest-generate;
+
+  # Hackage overlay entry for the generated static-asset manifest package.
+  obeliskGeneratedStaticOverlay = static: {
+    name = "obelisk-generated-static";
+    version = "0";
+    src = obelisk-generated-static-manifest static;
+  };
+
+  frontendJs = config:
+    config.haskell-nix.project.projectCross.ghcjs.hsPkgs.frontend.components.exes.frontend;
+
+  source-repository-packages = {
+    obelisk-asset-manifest = src + "/lib/asset/manifest";
+    obelisk-asset-serve-snap = src + "/lib/asset/serve-snap";
+    obelisk-backend = src + "/lib/backend";
+    obelisk-executable-config-inject = src + "/lib/executable-config/inject";
+    obelisk-executable-config-lookup = src + "/lib/executable-config/lookup";
+    obelisk-frontend = src + "/lib/frontend";
+    obelisk-route = src + "/lib/route";
+    obelisk-snap-extras = src + "/lib/snap-extras";
+    tabulation = src + "/lib/tabulation";
+
+    reflex-dom = src + "/deps/reflex-dom/reflex-dom";
+    reflex-dom-core = src + "/deps/reflex-dom/reflex-dom-core";
+  };
+
+  extraCabalProject = [
+    (builtins.readFile (src + "/lib/cabal.project.config"))
+  ];
+
+  inherit mkOptionalPackages;
+
+  # Force Simple build type so haskell.nix doesn't run a Setup.hs configure step.
+  buildTypeOverride = { config, lib, ... }:
+    let optional = mkOptionalPackages { inherit config lib; };
+    in {
+      packages = optional {
+        backend.package.buildType = lib.mkOverride 75 "Simple";
+        frontend.package.buildType = lib.mkOverride 75 "Simple";
+        frontend-custom.package.buildType = lib.mkOverride 75 "Simple";
+        static-manifest.package.buildType = lib.mkOverride 75 "Simple";
+      };
+    };
+
+  # Copy frontend.jsexe directory into $out/bin after GHCJS build.
+  jsexeOverride = { config, lib, ... }:
+    let optional = mkOptionalPackages { inherit config lib; };
+    in {
+      packages = optional {
+        frontend.components.exes.frontend.postInstall = ''
+          if [ -d dist/build/frontend/frontend.jsexe ]; then
+            cp -r dist/build/frontend/frontend.jsexe $out/bin/
+          fi
+        '';
+      };
+    };
+
+  # Symlink static assets into frontend's dataDir
+  # at both build time (preBuild) and in the installed output (postInstall).
+  frontendDataOverride = { static ? null }:
+    ({ config, lib, pkgs, ... }:
+      let dataDir = config.packages.frontend.package.dataDir;
+      in {
+        packages.frontend.components.library.preBuild = lib.optionalString (dataDir != "") ''
+          mkdir -p ${dataDir}
+          ${if static != null && static != {} then ''ln -sf ${static} ${dataDir}/static'' else ""}
+        '';
+        packages.frontend.components.library.postInstall = ''
+          for datadir in $data/share/*/*/frontend-*; do
+            ${if static != null && static != {} then ''ln -sf ${static} "$datadir/static"'' else ""}
+          done
+        '';
+      }
+    );
+
+  # Symlink static assets and frontend jsexe into backend's dataDir
+  # at both build time (preBuild) and in the installed output (postInstall).
+  backendDataOverride = { static ? null, frontendJs ? null }:
+    ({ config, lib, pkgs, ... }:
+      let dataDir = config.packages.backend.package.dataDir;
+      in {
+        packages.backend.components.library.preBuild = lib.optionalString (dataDir != "") ''
+          mkdir -p ${dataDir}
+          ${if static != null && static != {} then ''ln -sf ${static} ${dataDir}/static'' else ""}
+          ${if frontendJs != null && frontendJs != {} then ''ln -sf ${frontendJs}/bin/frontend.jsexe ${dataDir}/frontend.jsexe'' else ""}
+        '';
+        packages.backend.components.library.postInstall = ''
+          for datadir in $data/share/*/*/backend-*; do
+            ${if static != null && static != {} then ''ln -sf ${static} "$datadir/static"'' else ""}
+            ${if frontendJs != null && frontendJs != {} then ''ln -sf ${frontendJs}/bin/frontend.jsexe "$datadir/frontend.jsexe"'' else ""}
+          done
+        '';
+      }
+    );
+
+}

nix/default.nix

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+# nix-haskell module that wires obelisk overrides and hackage overlays
+# into a project. Declares `obelisk.static` and `obelisk.frontend.js` options;
+# when set, generates hackage overlay and wires assets into frontend/backend data dirs.
+# frontend.js defaults to the project's GHCJS-cross-compiled frontend.
+{ config, lib, system, ... }:
+
+let obeliskLib = import ./lib.nix { inherit system; };
+
+    static = config.obelisk.static;
+
+    frontendJs = config.obelisk.frontend.js;
+
+in {
+  options.obelisk = {
+    static = lib.mkOption {
+      type = lib.types.nullOr (lib.types.either lib.types.path lib.types.package);
+      default = null;
+      description = "Static assets path or derivation.";
+    };
+
+    frontend.js = lib.mkOption {
+      type = lib.types.nullOr lib.types.package;
+      default = obeliskLib.frontendJs config;
+      defaultText = lib.literalExpression "obeliskLib.frontendJs config";
+      description = "GHCJS-compiled frontend derivation.";
+    };
+  };
+
+  config = {
+    inherit (obeliskLib) extraCabalProject source-repository-packages;
+
+    hackage-overlays =
+      if static != null
+      then [ (obeliskLib.obeliskGeneratedStaticOverlay static) ]
+      else [];
+
+    overrides = [
+      obeliskLib.buildTypeOverride
+      obeliskLib.jsexeOverride
+      (obeliskLib.frontendDataOverride { inherit static; })
+      (obeliskLib.backendDataOverride { inherit static; inherit frontendJs; })
+    ];
+  };
+}