Improve nix with thunk.nix

default.nix

@@ -1,28 +1,21 @@
-{ pkgs ? import (builtins.fetchTarball { # 2020-02-13 (nixos-19.09)
-    url = "https://github.com/NixOS/nixpkgs/archive/e02fb6eaf70d4f6db37ce053edf79b731f13c838.tar.gz";
-    sha256 = "1dbjbak57vl7kcgpm1y1nm4s74gjfzpfgk33xskdxj9hjphi6mws";
-  }) {}
+{ pkgsFun ? import (import ./nix/nixpkgs/thunk.nix)
 
-, fetch ? { private ? false, fetchSubmodules ? false, owner, repo, rev, sha256, ... }:
-    if !fetchSubmodules && !private then builtins.fetchTarball {
-      url = "https://github.com/${owner}/${repo}/archive/${rev}.tar.gz"; inherit sha256;
-    } else (import <nixpkgs> {}).fetchFromGitHub {
-      inherit owner repo rev sha256 fetchSubmodules private;
-    }
-
-, rustOverlay ? import
-    "${fetch (builtins.fromJSON (builtins.readFile ./nix/nixpkgs-mozilla/github.json))}/rust-overlay.nix"
-    pkgs
-    pkgs
+, rustOverlay ? import "${import ./nix/nixpkgs-mozilla/thunk.nix}/rust-overlay.nix"
 
 # Rust manifest hash must be updated when rust-toolchain file changes.
-, rustPackages ? rustOverlay.rustChannelOf {
+, rustPackages ? pkgs.rustChannelOf {
     date = "2020-05-04";
     rustToolchain = ./rust-toolchain;
     sha256 = "07mp7n4n3cmm37mv152frv7p9q58ahjw5k8gcq48vfczrgm5qgiy";
   }
 
-, gitignoreNix ? fetch (builtins.fromJSON (builtins.readFile ./nix/gitignore.nix/github.json))
+, pkgs ? pkgsFun {
+    overlays = [
+      rustOverlay
+    ];
+  }
+
+, gitignoreNix ? import ./nix/gitignore.nix/thunk.nix
 
 }:
 
@@ -40,5 +33,5 @@ in rustPlatform.buildRustPackage {
   verifyCargoDeps = true;
 
   # Cargo hash must be updated when Cargo.lock file changes.
-  cargoSha256 = "039bvmi7ai5zd3k46jfr1r82sfn84x4hg7c34sxsncwifd8p5yc6";
+  cargoSha256 = "12kkhbfcl5x2k3n73rfrza7zmjf67s943gbcnvy061l80r6jry2s";
 }

nix/gitignore.nix/default.nix

@@ -1,8 +1,2 @@
 # DO NOT HAND-EDIT THIS FILE
-let fetch = { private ? false, fetchSubmodules ? false, owner, repo, rev, sha256, ... }:
-  if !fetchSubmodules && !private then builtins.fetchTarball {
-    url = "https://github.com/${owner}/${repo}/archive/${rev}.tar.gz"; inherit sha256;
-  } else (import <nixpkgs> {}).fetchFromGitHub {
-    inherit owner repo rev sha256 fetchSubmodules private;
-  };
-in import (fetch (builtins.fromJSON (builtins.readFile ./github.json)))
+import (import ./thunk.nix)

nix/gitignore.nix/github.json

@@ -3,6 +3,6 @@
   "repo": "gitignore.nix",
   "branch": "master",
   "private": false,
-  "rev": "2ced4519f865341adcb143c5d668f955a2cb997f",
-  "sha256": "0fc5bgv9syfcblp23y05kkfnpgh3gssz6vn24frs8dzw39algk2z"
+  "rev": "c4662e662462e7bf3c2a968483478a665d00e717",
+  "sha256": "1npnx0h6bd0d7ql93ka7azhj40zgjp815fw2r6smg8ch9p7mzdlx"
 }

nix/gitignore.nix/thunk.nix

@@ -0,0 +1,9 @@
+# DO NOT HAND-EDIT THIS FILE
+let fetch = { private ? false, fetchSubmodules ? false, owner, repo, rev, sha256, ... }:
+  if !fetchSubmodules && !private then builtins.fetchTarball {
+    url = "https://github.com/${owner}/${repo}/archive/${rev}.tar.gz"; inherit sha256;
+  } else (import <nixpkgs> {}).fetchFromGitHub {
+    inherit owner repo rev sha256 fetchSubmodules private;
+  };
+  json = builtins.fromJSON (builtins.readFile ./github.json);
+in fetch json

nix/nixpkgs-mozilla/default.nix

@@ -1,8 +1,2 @@
 # DO NOT HAND-EDIT THIS FILE
-let fetch = { private ? false, fetchSubmodules ? false, owner, repo, rev, sha256, ... }:
-  if !fetchSubmodules && !private then builtins.fetchTarball {
-    url = "https://github.com/${owner}/${repo}/archive/${rev}.tar.gz"; inherit sha256;
-  } else (import <nixpkgs> {}).fetchFromGitHub {
-    inherit owner repo rev sha256 fetchSubmodules private;
-  };
-in import (fetch (builtins.fromJSON (builtins.readFile ./github.json)))
+import (import ./thunk.nix)

nix/nixpkgs-mozilla/github.json

@@ -3,6 +3,6 @@
   "repo": "nixpkgs-mozilla",
   "branch": "master",
   "private": false,
-  "rev": "e912ed483e980dfb4666ae0ed17845c4220e5e7c",
-  "sha256": "08fvzb8w80bkkabc1iyhzd15f4sm7ra10jn32kfch5klgl0gj3j3"
+  "rev": "efda5b357451dbb0431f983cca679ae3cd9b9829",
+  "sha256": "11wqrg86g3qva67vnk81ynvqyfj0zxk83cbrf0p9hsvxiwxs8469"
 }

nix/nixpkgs-mozilla/thunk.nix

@@ -0,0 +1,9 @@
+# DO NOT HAND-EDIT THIS FILE
+let fetch = { private ? false, fetchSubmodules ? false, owner, repo, rev, sha256, ... }:
+  if !fetchSubmodules && !private then builtins.fetchTarball {
+    url = "https://github.com/${owner}/${repo}/archive/${rev}.tar.gz"; inherit sha256;
+  } else (import <nixpkgs> {}).fetchFromGitHub {
+    inherit owner repo rev sha256 fetchSubmodules private;
+  };
+  json = builtins.fromJSON (builtins.readFile ./github.json);
+in fetch json

nix/nixpkgs/default.nix

@@ -0,0 +1,2 @@
+# DO NOT HAND-EDIT THIS FILE
+import (import ./thunk.nix)

nix/nixpkgs/github.json

@@ -0,0 +1,8 @@
+{
+  "owner": "nixos",
+  "repo": "nixpkgs",
+  "branch": "nixos-20.03",
+  "private": false,
+  "rev": "252bfe0107587d40092057f338e9ffcf7bbd90cb",
+  "sha256": "1ljw98lcc04mlz6pprlgd1plinwl5q8fraakk6bx8igkiqlxaadn"
+}

nix/nixpkgs/thunk.nix

@@ -0,0 +1,9 @@
+# DO NOT HAND-EDIT THIS FILE
+let fetch = { private ? false, fetchSubmodules ? false, owner, repo, rev, sha256, ... }:
+  if !fetchSubmodules && !private then builtins.fetchTarball {
+    url = "https://github.com/${owner}/${repo}/archive/${rev}.tar.gz"; inherit sha256;
+  } else (import <nixpkgs> {}).fetchFromGitHub {
+    inherit owner repo rev sha256 fetchSubmodules private;
+  };
+  json = builtins.fromJSON (builtins.readFile ./github.json);
+in fetch json