Reorganize and update nixpkgs upstreams

This patch does a few things:

1. Switches from nixpkgs-unstable to nixos-unstable{,-small}, simply because
   nixpkgs-unstable is not in cache.nixos.org, but nixos-unstable is, and -small
   is the same but requires all tests to pass. So we should prefer
   nixos-unstable-small, whenever possible.

2. Reorganizes the nixpkgs import code such that Nixpkgs.nix returns an attrset
   of all the nixpkgs that I want to use, rather than putting other nixpkgs
   branches into the main one as an overlay. This is much simpler and explicit,
   but it meant I had to change a lot of usages throughtout the nix codebase.

3. As a consequence of 2, moves the overlays into separate files so they can be
   re-used across nixpkgs branches.

1 files changed, 156 insertions, 159 deletions

diff --git a/Biz/Bild.nix b/Biz/Bild.nix
index 7a07f36..329726a 100644
--- a/Biz/Bild.nix
+++ b/Biz/Bild.nix
@@ -2,175 +2,172 @@
 
 let
   constants = import ./Bild/Constants.nix;
-  lib = nixpkgs.lib;
-  # put all of our stuff in the 'bild' namespace
-in nixpkgs // {
-  bild = rec {
-    # provided by .envrc
-    root = builtins.getEnv "CODEROOT";
-
-    inherit (nixpkgs) sources;
-
-    haskell = rec {
-      inherit (constants) ghcCompiler;
-
-      # all available packages
-      deps = import ./Bild/Deps/Haskell.nix;
-      packages = lib.attrsets.getAttrs deps nixpkgs.haskellPackages;
-
-      # make a ghc with dependencies
-      ghcWith = nixpkgs.haskell.packages.${ghcCompiler}.ghcWithHoogle;
-
-      # ghc with all packages, used for generating bild's package database
-      ghcPackageSetFull = ghcWith (p: lib.attrsets.attrVals deps p);
-
-      # bild's dependencies, needs to be hand-written
-      ghcPackageSetBild = ghcWith (hpkgs:
-        with hpkgs; [
-          aeson
-          async
-          base
-          bytestring
-          conduit
-          conduit-extra
-          containers
-          directory
-          docopt
-          filepath
-          process
-          protolude
-          rainbow
-          regex-applicative
-          split
-          tasty
-          tasty-hunit
-          tasty-quickcheck
-          text
-          hostname
-          wai # can remove when removed from Biz.Log
-        ]);
-    };
+  stable = nixpkgs.nixos-23_05;
+in rec {
+  # provided by .envrc
+  root = builtins.getEnv "CODEROOT";
+
+  inherit (stable) sources lib makeWrapper stdenv;
+
+  haskell = rec {
+    inherit (constants) ghcCompiler;
+
+    # all available packages
+    deps = import ./Bild/Deps/Haskell.nix;
+    packages = lib.attrsets.getAttrs deps stable.haskellPackages;
+
+    # make a ghc with dependencies
+    ghcWith = stable.haskell.packages.${ghcCompiler}.ghcWithHoogle;
+
+    # ghc with all packages, used for generating bild's package database
+    ghcPackageSetFull = ghcWith (p: lib.attrsets.attrVals deps p);
+
+    # bild's dependencies, needs to be hand-written
+    ghcPackageSetBild = ghcWith (hpkgs:
+      with hpkgs; [
+        aeson
+        async
+        base
+        bytestring
+        conduit
+        conduit-extra
+        containers
+        directory
+        docopt
+        filepath
+        process
+        protolude
+        rainbow
+        regex-applicative
+        split
+        tasty
+        tasty-hunit
+        tasty-quickcheck
+        text
+        hostname
+        wai # can remove when removed from Biz.Log
+      ]);
+  };
 
-    lisp = { sbclWith = nixpkgs.lispPackages_new.sbclWithPackages; };
+  lisp = { sbclWith = stable.lispPackages_new.sbclWithPackages; };
 
-    python = {
-      packages = nixpkgs.python3Packages;
-      pythonWith = nixpkgs.python3.withPackages;
-      buildPythonApplication = nixpkgs.python3.pkgs.buildPythonApplication;
-    };
+  python = {
+    packages = stable.python3.pkgs;
+    pythonWith = stable.python3.withPackages;
+    buildPythonApplication = stable.python3.pkgs.buildPythonApplication;
+  };
 
-    # c packages are just nixpkgs, filtered to just the list of deps i want
-    c.packages = lib.attrsets.getAttrs (import ./Bild/Deps/C.nix) nixpkgs.pkgs;
+  # c packages are just stable, filtered to just the list of deps i want
+  c.packages = lib.attrsets.getAttrs (import ./Bild/Deps/C.nix) stable.pkgs;
 
-    # expose some packages for inclusion in os/image builds
-    pkgs = with nixpkgs.pkgs; {
-      inherit deadnix git hlint indent ormolu shellcheck nixfmt mypy pkg-config;
-      ruff = unstable.ruff;
-    };
+  # exposed packages for inclusion in builds
+  pkgs = with stable.pkgs; {
+    inherit deadnix git hlint indent ormolu shellcheck nixfmt mypy pkg-config
+      rustc cmark;
+    ruff = nixpkgs.nixos-unstable-small.ruff;
+  };
 
-    # a standard nix build for bild, for bootstrapping. this should be the only
-    # hand-written builder we need
-    bild = nixpkgs.stdenv.mkDerivation {
-      name = "bild";
+  # a standard nix build for bild, for bootstrapping. this should be the only
+  # hand-written builder we need
+  bild = stable.stdenv.mkDerivation {
+    name = "bild";
+    src = ../.;
+    nativeBuildInputs = [ haskell.ghcPackageSetBild ];
+    buildInputs = [ stable.makeWrapper ];
+    propagatedBuildInputs = with stable; [
+      pkg-config
+      git
+      # this is just to get access to ghc-pkg in bild
+      (haskell.ghcWith (_: [ ]))
+
+      # lisp deps, remove this when i implement nix builds for lisp
+      guile
+      (lisp.sbclWith
+        (p: with p; [ asdf alexandria ])) # just enough to build Example.lisp
+    ];
+    strictDeps = true;
+    buildPhase = ''
+      mkdir -p $out/bin $out/lib/ghc-${haskell.ghcPackageSetFull.version}
+      cp -r \
+        ${haskell.ghcPackageSetFull}/lib/ghc-${haskell.ghcPackageSetFull.version}/package.conf.d \
+        $out/lib/ghc-${haskell.ghcPackageSetFull.version}
+      ghc \
+        -threaded \
+        -Werror \
+        -i. \
+        --make Biz/Bild.hs \
+        -main-is Biz.Bild \
+        -o $out/bin/bild
+    '';
+    installPhase = ''
+      wrapProgram $out/bin/bild \
+        --prefix PATH : ${
+          lib.makeBinPath [ haskell.ghcPackageSetBild stable.pkgs.git ]
+        } \
+        --set GHC_PACKAGE_PATH \
+        $out/lib/ghc-${haskell.ghcPackageSetFull.version}/package.conf.d
+    '';
+  };
+
+  # wrapper around bild
+  runBildAnalyze = target:
+    stable.stdenv.mkDerivation rec {
+      name = "bild-analysis";
       src = ../.;
-      nativeBuildInputs = [ haskell.ghcPackageSetBild ];
-      buildInputs = [ nixpkgs.makeWrapper ];
-      propagatedBuildInputs = with nixpkgs; [
-        pkg-config
-        git
-        # this is just to get access to ghc-pkg in bild
-        (haskell.ghcWith (_: [ ]))
-
-        # lisp deps, remove this when i implement nix builds for lisp
-        guile
-        (lisp.sbclWith
-          (p: with p; [ asdf alexandria ])) # just enough to build Example.lisp
-      ];
-      strictDeps = true;
+      USER = "nixbld";
+      HOSTNAME = "nix-sandbox";
+      # we need to remove the $src root because bild expects paths relative to the
+      # working directory:
+      TARGET = "." + lib.strings.removePrefix (toString src) (toString target);
       buildPhase = ''
-        mkdir -p $out/bin $out/lib/ghc-${haskell.ghcPackageSetFull.version}
-        cp -r \
-          ${haskell.ghcPackageSetFull}/lib/ghc-${haskell.ghcPackageSetFull.version}/package.conf.d \
-          $out/lib/ghc-${haskell.ghcPackageSetFull.version}
-        ghc \
-          -threaded \
-          -Werror \
-          -i. \
-          --make Biz/Bild.hs \
-          -main-is Biz.Bild \
-          -o $out/bin/bild
-      '';
-      installPhase = ''
-        wrapProgram $out/bin/bild \
-          --prefix PATH : ${
-            lib.makeBinPath [ haskell.ghcPackageSetBild pkgs.git ]
-          } \
-          --set GHC_PACKAGE_PATH \
-          $out/lib/ghc-${haskell.ghcPackageSetFull.version}/package.conf.d
+        export CODEROOT=$(pwd)
+        mkdir $out
+        ${bild}/bin/bild --plan "$TARGET" 1> $out/analysis.json \
+          2> >(tee -a $out/stderr >&2)
       '';
+      installPhase = "exit 0";
     };
 
-    # wrapper around bild
-    runBildAnalyze = target:
-      nixpkgs.stdenv.mkDerivation rec {
-        name = "bild-analysis";
-        src = ../.;
-        USER = "nixbld";
-        HOSTNAME = "nix-sandbox";
-        # we need to remove the $src root because bild expects paths relative to the
-        # working directory:
-        TARGET = "."
-          + lib.strings.removePrefix (toString src) (toString target);
-        buildPhase = ''
-          export CODEROOT=$(pwd)
-          mkdir $out
-          ${bild}/bin/bild --plan "$TARGET" 1> $out/analysis.json \
-            2> >(tee -a $out/stderr >&2)
-        '';
-        installPhase = "exit 0";
-      };
-
-    # gather data needed for compiling by analyzing the main module. returns the
-    # json object of the build
-    analyze = target:
-      builtins.readFile (runBildAnalyze target + "/analysis.json");
-
-    # this does a bild build for the given target, but entirely in nix. its kinda
-    # like IFD, but not as costly, i think
-    run = target: import ./Bild/Builder.nix { analysisJSON = analyze target; };
-
-    # the main development environment
-    env = nixpkgs.pkgs.mkShell {
-      name = "bizdev";
-      # this should just be dev tools
-      buildInputs = with nixpkgs.pkgs; [
-        bat
-        bc
-        bild
-        ctags
-        fd
-        figlet
-        fzf
-        git
-        git-branchless
-        gitlint
-        jq
-        lolcat
-        nixpkgs.haskell.packages.${constants.ghcCompiler}.fast-tags
-        ormolu
-        ripgrep
-        tree
-        wemux
-      ];
-      shellHook = ''
-        export GHC_PACKAGE_PATH=${bild}/lib/ghc-${haskell.ghcPackageSetFull.version}/package.conf.d
-      '';
-    };
+  # gather data needed for compiling by analyzing the main module. returns the
+  # json object of the build
+  analyze = target:
+    builtins.readFile (runBildAnalyze target + "/analysis.json");
+
+  # this does a bild build for the given target, but entirely in nix. its kinda
+  # like IFD, but not as costly, i think
+  run = target: import ./Bild/Builder.nix { analysisJSON = analyze target; };
+
+  # the main development environment
+  env = stable.pkgs.mkShell {
+    name = "bizdev";
+    # this should just be dev tools
+    buildInputs = with stable.pkgs; [
+      bat
+      bc
+      bild
+      ctags
+      fd
+      figlet
+      fzf
+      git
+      git-branchless
+      gitlint
+      jq
+      lolcat
+      stable.haskell.packages.${constants.ghcCompiler}.fast-tags
+      ormolu
+      ripgrep
+      tree
+      wemux
+    ];
+    shellHook = ''
+      export GHC_PACKAGE_PATH=${bild}/lib/ghc-${haskell.ghcPackageSetFull.version}/package.conf.d
+    '';
+  };
 
-    # build an operating system. 'cfg' is the NixOS config
-    os = cfg: (nixpkgs.nixos (_args: cfg)).toplevel;
+  # build an operating system. 'cfg' is the NixOS config
+  os = cfg: (stable.nixos (_args: cfg)).toplevel;
 
-    # build a docker image
-    image = nixpkgs.pkgs.dockerTools.buildImage;
-  };
+  # build a docker image
+  image = stable.pkgs.dockerTools.buildImage;
 }