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.

7 files changed, 166 insertions, 112 deletions

diff --git a/Biz/Bild/Builder.nix b/Biz/Bild/Builder.nix
index 4bef830..d1fc48b 100644
--- a/Biz/Bild/Builder.nix
+++ b/Biz/Bild/Builder.nix
@@ -3,9 +3,9 @@
      wouldn't you?
    - Try to reuse as much upstream Nix as possible.
 */
-{ analysisJSON, nixpkgs ? import ../Bild.nix { } }:
-with nixpkgs;
+{ analysisJSON, bild ? import ../Bild.nix { } }:
 let
+  lib = bild.lib;
   analysis = builtins.fromJSON analysisJSON;
   build = _: target:
     let
@@ -53,7 +53,7 @@ let
       sysdeps_ = if isEmpty target.sysdeps then
         [ ]
       else
-        lib.attrsets.attrVals target.sysdeps pkgs;
+        lib.attrsets.attrVals target.sysdeps bild.pkgs;
 
       rundeps_ = if isEmpty target.rundeps then
         [ ]
@@ -63,16 +63,16 @@ let
       CODEROOT = ".";
 
       builders = {
-        base = stdenv.mkDerivation rec {
+        base = bild.stdenv.mkDerivation rec {
           inherit name src CODEROOT preBuild;
           buildInputs = langdeps_ ++ sysdeps_;
           installPhase = "install -D ${name} $out/bin/${name}";
           buildPhase = compileLine;
         };
 
-        haskell = stdenv.mkDerivation rec {
+        haskell = bild.stdenv.mkDerivation rec {
           inherit name src CODEROOT preBuild;
-          nativeBuildInputs = [ makeWrapper ];
+          nativeBuildInputs = [ bild.makeWrapper ];
           buildInputs = sysdeps_ ++ [
             (bild.haskell.ghcWith
               (p: (lib.attrsets.attrVals target.langdeps p)))
@@ -85,7 +85,7 @@ let
           '';
         };
 
-        c = stdenv.mkDerivation rec {
+        c = bild.stdenv.mkDerivation rec {
           inherit name src CODEROOT preBuild;
           buildInputs = langdeps_ ++ sysdeps_;
           installPhase = "install -D ${name} $out/bin/${name}";
@@ -155,4 +155,4 @@ let
   # return a single drv, so just take the first one for now. ideally i would only
   # pass Target, one at a time, (perhaps parallelized in haskell land) and then i
   # wouldn't need all of this let nesting
-in builtins.head (lib.attrsets.mapAttrsToList build analysis)
+in builtins.head (bild.lib.attrsets.mapAttrsToList build analysis)
diff --git a/Biz/Bild/Deps.nix b/Biz/Bild/Deps.nix
index 9a18c90..8f44dde 100644
--- a/Biz/Bild/Deps.nix
+++ b/Biz/Bild/Deps.nix
@@ -1,59 +1,6 @@
 _self: super:
 
-with import ./Constants.nix;
-let
-  buildCabal = sel: name: sel.callCabal2nix name super.sources.${name} { };
-  buildCabalSubdir = sel:
-    { name, src ? super.sources.${name}, subdir ? name }:
-    sel.callCabal2nix name (src + "/${subdir}") { };
-in rec {
-  haskell = super.haskell // {
-    packages = super.haskell.packages // {
-      "${ghcCompiler}" = super.haskell.packages."${ghcCompiler}".override
-        (_old: {
-          overrides = with super.pkgs.haskell.lib;
-            sel: sup:
-            super.overridePinnedDeps (buildCabal sel) // {
-              acid-state =
-                dontCheck sup.acid-state; # mac: "too many open files"
-              clay = doJailbreak sup.clay;
-              envy = doJailbreak sup.envy;
-              fast-tags =
-                sup.fast-tags.overrideAttrs (old: old // { patches = [ ]; });
-              generic-data = dontCheck
-                sup.generic-data; # https://github.com/Lysxia/generic-data/issues/56
-              readable =
-                doJailbreak sup.readable; # why is this even being built?
-              servant-auth = doJailbreak (buildCabalSubdir sel {
-                name = "servant-auth";
-                subdir = "servant-auth/servant-auth";
-              });
-              servant-server = doJailbreak sup.servant-server;
-              stripe-core = doJailbreak sup.stripe-core;
-              stripe-haskell = dontCheck sup.stripe-haskell;
-              stripe-http-client =
-                doJailbreak (dontCheck sup.stripe-http-client);
-              temporary = dontCheck sup.temporary;
-              wai-middleware-metrics = dontCheck sup.wai-middleware-metrics;
-            };
-        });
-    };
-  };
-
-  python3 = super.python3.override {
-    packageOverrides = _: pysuper:
-      with pysuper.pkgs.python3Packages; {
-        exllama = callPackage ./Deps/exllama.nix {
-          cudaPackages = super.pkgs.cudaPackages_11_7;
-        };
-        interegular = callPackage ./Deps/interegular.nix { };
-        outlines = callPackage ./Deps/outlines.nix { };
-        perscache = callPackage ./Deps/perscache.nix { };
-      };
-  };
-
-  python3Packages = python3.pkgs;
-
+{
   autogen = super.callPackage ./Deps/autogen.nix { };
 
   guile = super.guile_3_0;
diff --git a/Biz/Bild/Functions.nix b/Biz/Bild/Functions.nix
new file mode 100644
index 0000000..b725a00
--- /dev/null
+++ b/Biz/Bild/Functions.nix
@@ -0,0 +1,33 @@
+_: super: {
+  # Given a generic `builder`, will generate an attrset for all the packages
+  # pinned by `deps` with `builder` applied to the package. This attrset can
+  # then be merged with the rest of the packages in the set as part of an
+  # overlay or overrides.
+  overridePinnedDeps = builder:
+    super.lib.genAttrs (builtins.attrNames super.sources) builder;
+
+  # Modifies a derivation with our source and version, keeping super build
+  # rules. This will fail if build steps have changed, or if no build
+  # rules are available upstream.
+  overrideSource = depName:
+    if super ? "${depName}" && super.${depName} ? overrideAttrs then
+      super.${depName}.overrideAttrs (attrs:
+        attrs // rec {
+          version =
+            super.sources.${depName}.version or super.sources.${depName}.rev;
+          src = super.sources.${depName};
+        })
+    else
+      null;
+
+  # Simply override the 'src' attr on a drv. This is meant to be a simpler
+  # alternative to 'overrideSource' above. In an overaly, use it like:
+  #    mypkg = super.overrideSource super.mypkg super.sources.mypkg;
+  overrideSrc = dep: src:
+    dep.overrideAttrs (attrs:
+      attrs // {
+        version = src.version or src.rev;
+        src = src;
+      });
+}
+
diff --git a/Biz/Bild/Haskell.nix b/Biz/Bild/Haskell.nix
new file mode 100644
index 0000000..2c0529a
--- /dev/null
+++ b/Biz/Bild/Haskell.nix
@@ -0,0 +1,44 @@
+_self: super:
+
+let
+  ghcCompiler = "ghc924";
+  buildCabal = sel: name: sel.callCabal2nix name super.sources.${name} { };
+  buildCabalSubdir = sel:
+    { name, src ? super.sources.${name}, subdir ? name }:
+    sel.callCabal2nix name (src + "/${subdir}") { };
+in rec {
+
+  haskell = super.haskell // {
+    packages = super.haskell.packages // {
+      "${ghcCompiler}" = super.haskell.packages."${ghcCompiler}".override
+        (_old: {
+          overrides = with super.pkgs.haskell.lib;
+            sel: sup:
+            super.overridePinnedDeps (buildCabal sel) // {
+              acid-state =
+                dontCheck sup.acid-state; # mac: "too many open files"
+              clay = doJailbreak sup.clay;
+              envy = doJailbreak sup.envy;
+              fast-tags =
+                sup.fast-tags.overrideAttrs (old: old // { patches = [ ]; });
+              generic-data = dontCheck
+                sup.generic-data; # https://github.com/Lysxia/generic-data/issues/56
+              readable =
+                doJailbreak sup.readable; # why is this even being built?
+              servant-auth = doJailbreak (buildCabalSubdir sel {
+                name = "servant-auth";
+                subdir = "servant-auth/servant-auth";
+              });
+              servant-server = doJailbreak sup.servant-server;
+              stripe-core = doJailbreak sup.stripe-core;
+              stripe-haskell = dontCheck sup.stripe-haskell;
+              stripe-http-client =
+                doJailbreak (dontCheck sup.stripe-http-client);
+              temporary = dontCheck sup.temporary;
+              wai-middleware-metrics = dontCheck sup.wai-middleware-metrics;
+            };
+        });
+    };
+  };
+
+}
diff --git a/Biz/Bild/Nixpkgs.nix b/Biz/Bild/Nixpkgs.nix
index 8cb3448..f0e8698 100644
--- a/Biz/Bild/Nixpkgs.nix
+++ b/Biz/Bild/Nixpkgs.nix
@@ -2,54 +2,50 @@ let
   sources = import ./Sources.nix { sourcesFile = ./Sources.json; };
 
   config = {
+    allowAliases = true;
     allowBroken = true;
     allowUnfree = true;
+    checkMeta = true;
     cudaSupport = true;
   };
 
   system = __currentSystem;
 
-in import sources.nixos-23_05 {
-  inherit system config;
-  overlays = [
-    (_: _: { inherit sources; })
-
-    # add some functions
-    (_: old: {
-      # Given a generic `builder`, will generate an attrset for all the packages
-      # pinned by `deps` with `builder` applied to the package. This attrset can
-      # then be merged with the rest of the packages in the set as part of an
-      # overlay or overrides.
-      overridePinnedDeps = builder:
-        old.lib.genAttrs (builtins.attrNames sources) builder;
-
-      # Modifies a derivation with our source and version, keeping old build
-      # rules. This will fail if build steps have changed, or if no build
-      # rules are available upstream.
-      overrideSource = depName:
-        if old ? "${depName}" && old.${depName} ? overrideAttrs then
-          old.${depName}.overrideAttrs (attrs:
-            attrs // rec {
-              version = sources.${depName}.version or sources.${depName}.rev;
-              src = sources.${depName};
-            })
-        else
-          null;
-    })
-
-    # override pinned deps with our sources, this must come before other
-    # package overlays, because of the 'null' above
-    (_: pkgs: pkgs.overridePinnedDeps pkgs.overrideSource)
-
-    # add other nixpkgs distributions
-    (_: _: {
-      unstable = import sources.nixpkgs-unstable { inherit system config; };
-      nixos-23_11 = import sources.nixos-23_11 { inherit system config; };
-    })
-
-    # add our hand-written derivations
-    (import ./Deps.nix)
-    (_: pkgs: { niv = import pkgs.sources.niv { }; })
-  ];
+in {
+  nixos-23_05 = import sources.nixos-23_05 {
+    inherit system config;
+    overlays = [
+      (_: _: { inherit sources; })
+
+      (import ./Functions.nix)
+
+      # override pinned deps with our sources, this must come before other
+      # package overlays, because of the 'null' from 'overrideSource'
+      (_: pkgs: pkgs.overridePinnedDeps pkgs.overrideSource)
+
+      (import ./Deps.nix)
+      (import ./Python.nix)
+      (import ./Haskell.nix)
+    ];
+  };
+
+  nixos-23_11 = import sources.nixos-23_11 {
+    inherit system config;
+    overlays = [
+      (_: _: { inherit sources; })
+      (import ./Functions.nix)
+      (import ./Deps.nix)
+    ];
+  };
+
+  nixos-unstable-small = import sources.nixos-unstable-small {
+    inherit system config;
+    overlays = [
+      (_: _: { inherit sources; })
+      (import ./Functions.nix)
+      (import ./Deps.nix)
+    ];
+  };
+
 }
 
diff --git a/Biz/Bild/Python.nix b/Biz/Bild/Python.nix
new file mode 100644
index 0000000..51f35f1
--- /dev/null
+++ b/Biz/Bild/Python.nix
@@ -0,0 +1,23 @@
+_self: super: {
+  python3 = super.python3.override {
+    packageOverrides = _pyself: pysuper:
+      with pysuper.pkgs.python3Packages;
+      let dontCheck = p: p.overridePythonAttrs (_: { doCheck = false; });
+      in {
+        exllama = callPackage ./Deps/exllama.nix {
+          cudaPackages = super.pkgs.cudaPackages_11_7;
+        };
+        exllamav2 = callPackage ./Deps/exllamav2.nix {
+          cudaPackages = super.pkgs.cudaPackages_11_7;
+        };
+        interegular = callPackage ./Deps/interegular.nix { };
+        mypy = dontCheck pysuper.mypy;
+        outlines = callPackage ./Deps/outlines.nix { };
+        perscache = callPackage ./Deps/perscache.nix { };
+        safetensors = super.nixos-23_11.python310Packages.safetensors.override {
+          buildPythonPackage = pysuper.pkgs.python3Packages.buildPythonPackage;
+        };
+        tokenizers = dontCheck pysuper.tokenizers;
+      };
+  };
+}
diff --git a/Biz/Bild/Sources.json b/Biz/Bild/Sources.json
index 52112b5..ed6b096 100644
--- a/Biz/Bild/Sources.json
+++ b/Biz/Bild/Sources.json
@@ -121,17 +121,28 @@
         "url_template": "https://gitlab.com/simple-nixos-mailserver/nixos-mailserver/-/archive/<rev>/nixos-mailserver-<rev>.tar.gz",
         "version": "master"
     },
-    "nixpkgs-unstable": {
-        "branch": "master",
-        "description": "Nix Packages collection",
-        "homepage": "https://github.com/nixos/nixpkgs",
-        "name": "nixpkgs",
+    "nixos-unstable": {
+        "branch": "nixos-unstable",
+        "description": "Nix Packages collection & NixOS",
+        "homepage": "",
+        "owner": "nixos",
+        "repo": "nixpkgs",
+        "rev": "fd281bd6b7d3e32ddfa399853946f782553163b5",
+        "sha256": "1hy81yj2dcg6kfsm63xcqf8kvigxglim1rcg1xpmy2rb6a8vqvsj",
+        "type": "tarball",
+        "url": "https://github.com/nixos/nixpkgs/archive/fd281bd6b7d3e32ddfa399853946f782553163b5.tar.gz",
+        "url_template": "https://github.com/<owner>/<repo>/archive/<rev>.tar.gz"
+    },
+    "nixos-unstable-small": {
+        "branch": "nixos-unstable-small",
+        "description": "Nix Packages collection & NixOS",
+        "homepage": "",
         "owner": "nixos",
         "repo": "nixpkgs",
-        "rev": "0b6c600141ae4c516593d05b35294c44d55344da",
-        "sha256": "0x76w3rnkmwgscjljd33pv50r2057lbhcwhf1qvmp36vxrxa98w5",
+        "rev": "6cc8dbb00974248cdd1b7ebd05cbc7c0799ce974",
+        "sha256": "09lyljxmzvwc71j5s2k0ya3y04ya3lxy8bgcm36gi8vmrn42dgv0",
         "type": "tarball",
-        "url": "https://github.com/nixos/nixpkgs/archive/0b6c600141ae4c516593d05b35294c44d55344da.tar.gz",
+        "url": "https://github.com/nixos/nixpkgs/archive/6cc8dbb00974248cdd1b7ebd05cbc7c0799ce974.tar.gz",
         "url_template": "https://github.com/<owner>/<repo>/archive/<rev>.tar.gz"
     },
     "outlines": {