default.nix

@@ -3,8 +3,16 @@
 # if evaluating inside the store, import the outputs.nix file
 
 let
-  # Ideally this file should not depend on nixpkgs lib itself, but I like the utilities here
+  contains = str: substr: let
-  lib = (import "${(import ./inputs.nix {}).nixpkgs}/lib");
+    str_length = builtins.stringLength str;
+    substr_length = builtins.stringLength substr;
+    listOfPossibleSubstrings = builtins.genList (i: builtins.substring i substr_length str) (str_length - substr_length + 1);
+  in if substr_length > str_length then false else builtins.any (x: x == substr) listOfPossibleSubstrings;
+
+  endsWith = str: substr: let
+    str_length = builtins.stringLength str;
+    substr_length = builtins.stringLength substr;
+  in if substr_length > str_length then false else builtins.substring (str_length - substr_length) str_length str == substr;
 
   gitignore = builtins.filter (v:
       # ignore comments and empty lines
@@ -24,11 +32,11 @@ let
       if pattern == "*" then true
       else if pattern == ".*" then true
       else if pattern == "*.*" then true
-      else if builtins.substring 0 2 pattern == "*." then lib.hasSuffix (builtins.substring 0 2 pattern) path
+      else if builtins.substring 0 2 pattern == "*." then endsWith path (builtins.substring 0 2 pattern)
-      else if lib.hasInfix "*" pattern then abort unsupportedPatternMessage
+      else if contains pattern "*" then abort unsupportedPatternMessage
       else if patternLength > 2 && builtins.substring 0 2 pattern == "./" then abort unsupportedPatternMessage
       else if patternLength > 1 && builtins.substring 0 1 pattern == "/" then abort unsupportedPatternMessage
-      else lib.hasInfix pattern path
+      else contains path pattern
   ) gitignore;
 
   currentFilePath = (builtins.unsafeGetAttrPos "any" { any = "any"; }).file;

inputs.nix

@@ -15,11 +15,6 @@ let self = {
     url = "https://github.com/NixOS/nixpkgs/archive/${lock.nixpkgs.revision}.tar.gz";
     sha256 = "${lock.nixpkgs.sha256}";
   };
-  nixpkgs-unstable = builtins.fetchTarball {
-    name = "nixpkgs-unstable";
-    url = "https://github.com/NixOS/nixpkgs/archive/${lock.nixpkgs-unstable.revision}.tar.gz";
-    sha256 = "${lock.nixpkgs-unstable.sha256}";
-  };
   cosmic-modules = builtins.fetchTarball {
     name = "cosmic-modules";
     url = "https://github.com/lilyinstarlight/nixos-cosmic/archive/${lock.cosmic-modules.revision}.tar.gz";

lib/overlays/version-info-fixup.nix

@@ -1,8 +1,8 @@
-{ revision }:
+{ inputs ? import ../../inputs.nix {} }:
 
 selfLib: superLib: {
   trivial = superLib.trivial // {
-    versionSuffix = ".git.${builtins.substring 0 12 revision}";
+    versionSuffix = ".git.${builtins.substring 0 12 inputs.lock.nixpkgs.revision}";
-    revisionWithDefault = default: revision;
+    revisionWithDefault = default: inputs.lock.nixpkgs.revision or default;
   };
 }

lock.nix

@@ -7,10 +7,6 @@
     revision = "3f0a8ac25fb674611b98089ca3a5dd6480175751";
     sha256 = "10i7fllqjzq171afzhdf2d9r1pk9irvmq5n55h92rc47vlaabvr4";
   };
-  nixpkgs-unstable = {
-    revision = "130595eba61081acde9001f43de3248d8888ac4a";
-    sha256 = "0sw7zg4gal3wpz51ch1v36pdan9z73d4f3yrggh8h2clxs8jdgsx";
-  };
   cosmic-modules = {
     revision = "a934c861065b6b1aca9a859c45631336e0e8560c";
     sha256 = "1p0hs2z1h9fl25qvrlprf63cj1v0m7hr2y051mykjvdxikvn5a47";

nix-os/unstable-packages.nix

@@ -1,14 +1,8 @@
-{
+{config, pkgs, lib, ...}:
-  config,
-  lib,
-  pkgs,
-  self,
-  ...
-}:
 
 let
   cfg = config.unstable;
-  unstableOverlay = self.overlays.unstableWithMeta;
+  unstableOverlay = import ../pkgs/overlays/unstable.nix;
 in
 {
   options.unstable = {

outputs.nix

@@ -5,7 +5,7 @@
 
 let
 
-lib = (import "${inputs.nixpkgs}/lib").extend (import ./lib/overlays/version-info-fixup.nix { revision = inputs.lock.nixpkgs.revision; });
+lib = (import "${inputs.nixpkgs}/lib").extend (import ./lib/overlays/version-info-fixup.nix { inherit inputs; });
 
 self = {
   inherit inputs lib self;
@@ -15,7 +15,7 @@ self = {
   overlays = {
     cosmicPackages = import ./pkgs/overlays/cosmic-packages.nix { inherit inputs; };
     selfExpr = import ./pkgs/overlays/selfExpr.nix { nixpkgsPath = inputs.nixpkgs; };
-    unstableWithMeta = import ./pkgs/overlays/unstable-with-meta.nix { unstableSource = inputs.nixpkgs-unstable; revision = inputs.lock.nixpkgs-unstable.revision; };
+    unstable = import ./pkgs/overlays/unstable.nix;
     versionInfoFixup = import ./pkgs/overlays/version-info-fixup.nix { inherit inputs; };
   };
   nixosConfigurations = let
@@ -26,7 +26,7 @@ self = {
         ( # regular .nix files
           (type == "regular" && lib.hasSuffix ".nix" name)
           || # directories that contain a default.nix file
-          (type == "directory" && builtins.pathExists "${./.}/hosts/${name}/default.nix")
+          (type == "directory" && builtins.pathExists "${./hosts}/${name}/default.nix")
         )
         # filter out files that start with .
         && !lib.hasPrefix "." name

pkgs/overlays/unstable-with-meta.nix

@@ -1,16 +0,0 @@
-{
-  unstableSource,
-  revision,
-}: self: super:
-
-let
-  version = builtins.readFile "${unstableSource}/lib/.version" + ".git." + builtins.substring 0 12 revision;
-  useUnstable = self.config.useUnstable or true;
-
-in
-import ./unstable-from-source.nix {
-  inherit unstableSource;
-} self super // {
-  unstableVersion = self.lib.optionalString useUnstable version;
-  unstableRevision = self.lib.optionalString useUnstable revision;
-}

pkgs/overlays/unstable.nix

@@ -0,0 +1,24 @@
+self: super:
+
+let
+  nixos = self.config.nixos or true;
+  useUnstable = self.config.useUnstable or true;
+
+  unstablePkgsExprs = if nixos
+      then builtins.fetchTarball "https://channels.nixos.org/nixos-unstable/nixexprs.tar.xz"
+      else builtins.fetchTarball "https://channels.nixos.org/nixpkgs-unstable/nixexprs.tar.xz";
+
+  # Compiled nixpkgs expression eg expressions from a nix channel
+  nixpkgsVersion = builtins.concatStringsSep "." [
+    (builtins.readFile "${unstablePkgsExprs}/.version")
+    (builtins.readFile "${unstablePkgsExprs}/.version-suffix")
+  ];
+
+  nixpkgsRevision = (builtins.readFile "${unstablePkgsExprs}/.git-revision");
+in
+import ./unstable-from-source.nix {
+  unstableSource = unstablePkgsExprs;
+} self super // {
+  unstableVersion = self.lib.optionalString useUnstable nixpkgsVersion;
+  unstableRevision = self.lib.optionalString useUnstable nixpkgsRevision;
+}

pkgs/overlays/version-info-fixup.nix

@@ -1,12 +1,5 @@
 { inputs ? import ../../inputs.nix {} }:
 
 self: super: {
-  lib = super.lib.extend (import ../../lib/overlays/version-info-fixup.nix { revision = inputs.lock.nixpkgs.revision; });
+  lib = super.lib.extend (import ../../lib/overlays/version-info-fixup.nix { inherit inputs; });
-} //
-super.lib.optionalAttrs (super ? unstable && super ? unstableRevision) {
-  unstable = super.unstable // {
-    lib = super.unstable.lib.extend (import ../../lib/overlays/version-info-fixup.nix {
-      revision = super.unstableRevision;
-    });
-  };
 }

pkgs/top-level/default.nix

@@ -14,7 +14,7 @@ let
     overlays = (args.overlays or []) ++ [
       # ../.. should be nix store path that represents self in outputs.nix that is gc-rooted by this point
       ( import ../overlays/selfExpr.nix { nixpkgsPath = "${builtins.toString ../..}/pkgs/top-level/impure.nix"; } )
-      ( import ../overlays/unstable-with-meta.nix { unstableSource = inputs.nixpkgs-unstable; revision = inputs.lock.nixpkgs-unstable.revision; } )
+      ( import ../overlays/unstable.nix )
       ( import ../overlays/version-info-fixup.nix { inherit inputs; } )
       ( import ./by-name-overlay.nix ../by-name )
     ];