nix: expose ihaskellOverlay in flake

flake.nix now:
- expose an overlay to be used by for instance jupyterWith
- disabled tests 'cos failing
- bring haskell-language-server though it seems to choke on codebase

flake.lock

@@ -87,11 +87,11 @@
         "pre-commit-hooks": "pre-commit-hooks"
       },
       "locked": {
-        "lastModified": 1633522486,
-        "narHash": "sha256-rKtQFo5IPRatGwDWfC0KGBtzo6PmDo7GEE2MbO0ghJ4=",
+        "lastModified": 1633827357,
+        "narHash": "sha256-TjTkSYMjce1ejPVvidnFWluxij6LGZV5TSmx2IQPYX4=",
         "owner": "haskell",
         "repo": "haskell-language-server",
-        "rev": "4ab35bc93ba60e488b0c952e4cdb4068c06596e2",
+        "rev": "195fa4c0fff2fcc0c0001b28216b36a890629cd2",
         "type": "github"
       },
       "original": {
@@ -118,17 +118,17 @@
     },
     "nixpkgs_2": {
       "locked": {
-        "lastModified": 1630761588,
-        "narHash": "sha256-7GXckvZy7DGh2KIyfdArqwnyeSc5Owy1fumEDQyd8eY=",
+        "lastModified": 1634515797,
+        "narHash": "sha256-elgCUC2khtBkOSpE4gDymNvthTZAI4hGI2iNu3YEUkA=",
         "owner": "NixOS",
         "repo": "nixpkgs",
-        "rev": "a51aa6523bd8ee985bc70987909eff235900197a",
+        "rev": "5f0194220f2402b06f7f79bba6351895facb5acb",
         "type": "github"
       },
       "original": {
         "owner": "NixOS",
+        "ref": "nixos-unstable",
         "repo": "nixpkgs",
-        "rev": "a51aa6523bd8ee985bc70987909eff235900197a",
         "type": "github"
       }
     },

flake.nix

@@ -3,7 +3,7 @@
 
   inputs = {
 
-    nixpkgs.url = "github:NixOS/nixpkgs?rev=a51aa6523bd8ee985bc70987909eff235900197a";
+    nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
     flake-utils.url = "github:numtide/flake-utils";
     hls.url = "github:haskell/haskell-language-server";
 
@@ -13,20 +13,44 @@
     };
   };
 
-  outputs = inputs@{ self, hls, nixpkgs, flake-utils, ... }:
+  outputs = { self, hls, nixpkgs, flake-utils, ... }:
     flake-utils.lib.eachSystem ["x86_64-linux"] (system: let
+
+      compilerVersion = "8107";
+
       pkgs = import nixpkgs {
         inherit system;
       };
-      compilerVersion = "8107";
 
       ihaskellEnv = import ./release.nix {
         compiler = "ghc${compilerVersion}";
         nixpkgs = pkgs;
-        # just for the example
-        packages = p: [ p.Frames ];
       };
+
+      hsPkgs = pkgs.haskell.packages."ghc${compilerVersion}";
+
+      myModifier = drv:
+        pkgs.haskell.lib.addBuildTools drv (with hsPkgs; [
+          cabal-install
+          self.inputs.hls.packages."${system}"."haskell-language-server-${compilerVersion}"
+        ]);
     in {
-      defaultPackage = ihaskellEnv;
+
+      packages = {
+        ihaskell = hsPkgs.developPackage {
+          root =  pkgs.lib.cleanSource ./.;
+          name = "ihaskell";
+          returnShellEnv = false;
+          modifier = pkgs.haskell.lib.dontCheck;
+          overrides = ihaskellEnv.ihaskellOverlay;
+          withHoogle = true;
+        };
+
+        ihaskellEnv = ihaskellEnv;
+      };
+
+      defaultPackage = self.packages.${system}.ihaskell;
+
+      devShell = (myModifier self.packages.${system}.ihaskell).envFunc {withHoogle=true;};
     });
 }

release.nix

@@ -16,8 +16,11 @@ let
       (display: { name = "ihaskell-${display}"; value = self.callCabal2nix display "${ihaskell-src}/ihaskell-display/ihaskell-${display}" {}; })
       [ "aeson" "blaze" "charts" "diagrams" "gnuplot" "graphviz" "hatex" "juicypixels" "magic" "plot" "rlangqq" "static-canvas" "widgets" ]);
   haskellPackages = nixpkgs.haskell.packages."${compiler}".override (old: {
-    overrides = nixpkgs.lib.composeExtensions (old.overrides or (_: _: {})) (self: super: {
-      ihaskell          = nixpkgs.haskell.lib.overrideCabal (
+    overrides = nixpkgs.lib.composeExtensions (old.overrides or (_: _: {})) ihaskellOverlay;
+  });
+
+  ihaskellOverlay = (self: super: {
+      ihaskell = nixpkgs.haskell.lib.overrideCabal (
                           self.callCabal2nix "ihaskell" ihaskell-src {}) (_drv: {
         preCheck = ''
           export HOME=$TMPDIR/home
@@ -28,7 +31,7 @@ let
       ghc-parser        = self.callCabal2nix "ghc-parser" (builtins.path { path = ./ghc-parser; name = "ghc-parser-src"; }) {};
       ipython-kernel    = self.callCabal2nix "ipython-kernel" (builtins.path { path = ./ipython-kernel; name = "ipython-kernel-src"; }) {};
     } // displays self);
-  });
+
   # statically linking against haskell libs reduces closure size at the expense
   # of startup/reload time, so we make it configurable
   ihaskellExe = if staticExecutable
@@ -67,7 +70,7 @@ let
   };
   ihaskellBuildEnvFunc = { ihaskellEnv, jupyterlab, systemPackages, ihaskellDataDir }: nixpkgs.buildEnv {
     name = "ihaskell-with-packages";
-    buildInputs = [ nixpkgs.makeWrapper ];
+    nativeBuildInputs = [ nixpkgs.makeWrapper ];
     paths = [ ihaskellEnv jupyterlab ];
     postBuild = ''
       for prg in $out/bin"/"*;do
@@ -82,6 +85,7 @@ let
       inherit haskellPackages;
       inherit ihaskellExe;
       inherit ihaskellEnv;
+      inherit ihaskellOverlay;
       inherit ihaskellLabextension;
       inherit jupyterlab;
       inherit ihaskellGhcLibFunc;