refactor nix

default.nix

@@ -1,2 +0,0 @@
-{ pkgs ? import <nixpkgs> {} }:
-(pkgs.ocamlPackages.callPackage ./nix/package.nix {}).package

nix/package.nix

@@ -1,45 +0,0 @@
-{
-  lib,
-  mkShell,
-
-  buildDunePackage,
-  eio,
-  eio_main,
-
-  ocaml,
-  dune_3,
-  odoc,
-  utop
-}:
-
-{
-  package =
-    let
-      sourceRoot = ../.;
-      fs = lib.fileset;
-      sourceFiles = fs.difference
-        (fs.gitTracked sourceRoot)
-        (fs.fileFilter (file: file.hasExt "nix") sourceRoot);
-      sourceSet = fs.toSource { root = sourceRoot; fileset = sourceFiles; };
-    in buildDunePackage rec {
-      pname = "bk910x";
-      version = "devel";
-      src = sourceSet;
-
-      minimalOCamlVersion = "5.1";
-      dontStrip = true;
-
-      propagatedBuildInputs = [ eio eio_main ];
-    };
-
-  shell = mkShell {
-    nativeBuildInputs = [
-      # base
-      ocaml dune_3 odoc
-      # shell
-      utop
-      # package deps
-      eio eio_main
-    ];
-  };
-}

package.nix

@@ -0,0 +1,37 @@
+{
+  lib,
+  mkShell,
+
+  buildDunePackage,
+  eio,
+  eio_main,
+
+  ocaml,
+  dune_3,
+  odoc,
+  utop,
+
+  enableShell ? false
+}:
+
+let
+  sourceRoot = ./.;
+  fs = lib.fileset;
+  sourceFiles = fs.difference
+    (fs.gitTracked sourceRoot)
+    (fs.fileFilter (file: file.hasExt "nix") sourceRoot);
+  sourceSet = fs.toSource { root = sourceRoot; fileset = sourceFiles; };
+in buildDunePackage rec {
+  pname = "bk910x";
+  version = "devel";
+  src = sourceSet;
+
+  minimalOCamlVersion = "5.1";
+  dontStrip = true;
+
+  propagatedBuildInputs = [ eio eio_main ];
+
+  nativeBuildInputs = lib.optionals enableShell [
+    ocaml dune_3 odoc utop
+  ];
+}

shell.nix

@@ -1,2 +0,0 @@
-{ pkgs ? import <nixpkgs> {} }:
-(pkgs.ocamlPackages.callPackage ./nix/package.nix {}).shell