nix shell w/ npins

npins/default.nix

@@ -0,0 +1,80 @@
+# Generated by npins. Do not modify; will be overwritten regularly
+let
+  data = builtins.fromJSON (builtins.readFile ./sources.json);
+  version = data.version;
+
+  mkSource =
+    spec:
+    assert spec ? type;
+    let
+      path =
+        if spec.type == "Git" then
+          mkGitSource spec
+        else if spec.type == "GitRelease" then
+          mkGitSource spec
+        else if spec.type == "PyPi" then
+          mkPyPiSource spec
+        else if spec.type == "Channel" then
+          mkChannelSource spec
+        else
+          builtins.throw "Unknown source type ${spec.type}";
+    in
+    spec // { outPath = path; };
+
+  mkGitSource =
+    {
+      repository,
+      revision,
+      url ? null,
+      hash,
+      branch ? null,
+      ...
+    }:
+    assert repository ? type;
+    # At the moment, either it is a plain git repository (which has an url), or it is a GitHub/GitLab repository
+    # In the latter case, there we will always be an url to the tarball
+    if url != null then
+      (builtins.fetchTarball {
+        inherit url;
+        sha256 = hash; # FIXME: check nix version & use SRI hashes
+      })
+    else
+      assert repository.type == "Git";
+      let
+        urlToName =
+          url: rev:
+          let
+            matched = builtins.match "^.*/([^/]*)(\\.git)?$" repository.url;
+
+            short = builtins.substring 0 7 rev;
+
+            appendShort = if (builtins.match "[a-f0-9]*" rev) != null then "-${short}" else "";
+          in
+          "${if matched == null then "source" else builtins.head matched}${appendShort}";
+        name = urlToName repository.url revision;
+      in
+      builtins.fetchGit {
+        url = repository.url;
+        rev = revision;
+        inherit name;
+        # hash = hash;
+      };
+
+  mkPyPiSource =
+    { url, hash, ... }:
+    builtins.fetchurl {
+      inherit url;
+      sha256 = hash;
+    };
+
+  mkChannelSource =
+    { url, hash, ... }:
+    builtins.fetchTarball {
+      inherit url;
+      sha256 = hash;
+    };
+in
+if version == 3 then
+  builtins.mapAttrs (_: mkSource) data.pins
+else
+  throw "Unsupported format version ${toString version} in sources.json. Try running `npins upgrade`"

npins/sources.json

@@ -0,0 +1,11 @@
+{
+  "pins": {
+    "nixpkgs": {
+      "type": "Channel",
+      "name": "nixpkgs-unstable",
+      "url": "https://releases.nixos.org/nixpkgs/nixpkgs-24.11pre683804.a1d92660c6b3/nixexprs.tar.xz",
+      "hash": "0lzd1g9x7ihscdajc2g9f0jyykymw6r1lq2ir5g0shjzjf0jc5la"
+    }
+  },
+  "version": 3
+}

shell.nix

@@ -0,0 +1,29 @@
+let
+  sources = import ./npins;
+  pkgs = import sources.nixpkgs {
+    config.android_sdk.accept_license = true;
+  };
+  jdk = pkgs.jdk17_headless;
+  # note: can use pkgs.androidenv.androidPkgs.androidsdk
+  # but it pulls in lots of toolchains see https://github.com/NixOS/nixpkgs/blob/master/pkgs/development/mobile/androidenv/default.nix#L18
+  androidSdk' =
+    (pkgs.androidenv.composeAndroidPackages {
+      platformVersions = [ "33" ];
+      includeEmulator = false;
+      includeSystemImages = false;
+      includeNDK = false;
+    }).androidsdk;
+in
+pkgs.mkShellNoCC {
+  packages = with pkgs; [
+    androidSdk'
+    npins
+    nixfmt-rfc-style
+  ];
+  shellHook = ''
+    export JAVA_HOME=${jdk}
+    export PATH="${jdk}/bin:$PATH"
+    export ANDROID_SDK=${androidSdk'}/libexec/android-sdk
+    exec bash
+  '';
+}