pin nixpkgs, use niv

default.nix

@@ -1,11 +1,10 @@
-{ system ? builtins.currentSystem }:
+{ sources ? import ./nix/sources.nix, system ? builtins.currentSystem
+, pkgs ? import sources.nixpkgs { inherit system; } }:
 
 let
-  pkgs = import <nixpkgs> { inherit system; };
-
   callPackage = pkgs.lib.callPackageWith (pkgs // self);
-
   x = callPackage ./pkgs/x { };
+  quickserv = callPackage sources.quickserv { };
 
   self = {
     MoonPlus = callPackage ./pkgs/moonplus { };
@@ -23,6 +22,7 @@ let
     license = x.license;
     mainsanow = x.mainsanow;
     prefix = x.prefix;
-    quickserv = x.quickserv;
+
+    inherit x quickserv;
   };
 in self

nix/sources.json

@@ -0,0 +1,56 @@
+{
+    "MoonPlus": {
+        "branch": "master",
+        "description": "Moonscript compiler written in C++.",
+        "homepage": "",
+        "owner": "pigpigyyy",
+        "repo": "MoonPlus",
+        "rev": "d0583829535462a070e7ae90c6ea13f14244d060",
+        "sha256": "02nf7fgj7mbl2aapkirwiclbacjzqqia9gfqr0yj7z0ky7z2ai22",
+        "type": "tarball",
+        "url": "https://github.com/pigpigyyy/MoonPlus/archive/d0583829535462a070e7ae90c6ea13f14244d060.tar.gz",
+        "url_template": "https://github.com/<owner>/<repo>/archive/<rev>.tar.gz"
+    },
+    "niv": {
+        "branch": "master",
+        "description": "Easy dependency management for Nix projects",
+        "homepage": "https://github.com/nmattia/niv",
+        "owner": "nmattia",
+        "repo": "niv",
+        "rev": "2ecfd86b631714b457e56d70dd83fa60435baeb6",
+        "sha256": "01j6727cws8blg1npp54b4w6xa0gpgyzhyws2vqgp8clnlnmqqhi",
+        "type": "tarball",
+        "url": "https://github.com/nmattia/niv/archive/2ecfd86b631714b457e56d70dd83fa60435baeb6.tar.gz",
+        "url_template": "https://github.com/<owner>/<repo>/archive/<rev>.tar.gz"
+    },
+    "nixpkgs": {
+        "branch": "nixpkgs-unstable",
+        "description": "A read-only mirror of NixOS/nixpkgs tracking the released channels. Send issues and PRs to",
+        "homepage": "https://github.com/NixOS/nixpkgs",
+        "owner": "NixOS",
+        "repo": "nixpkgs-channels",
+        "rev": "cc1ae9f21b9e0ce998e706a3de1bad0b5259f22d",
+        "sha256": "0zjafww05h50ncapw51b5qxgbv9prjyag0j22jnfc3kcs5xr4ap0",
+        "type": "tarball",
+        "url": "https://github.com/NixOS/nixpkgs-channels/archive/cc1ae9f21b9e0ce998e706a3de1bad0b5259f22d.tar.gz",
+        "url_template": "https://github.com/<owner>/<repo>/archive/<rev>.tar.gz"
+    },
+    "quickserv": {
+        "ref": "master",
+        "repo": "https://tulpa.dev/Xe/quickserv.git",
+        "rev": "cde2c24e27aa5e7f213e606414903fccac8a59cb",
+        "type": "git"
+    },
+    "tools": {
+        "branch": "master",
+        "description": "[mirror] Go Tools",
+        "homepage": "https://godoc.org/golang.org/x/tools",
+        "owner": "golang",
+        "repo": "tools",
+        "rev": "0abbfa5d31cd6db879f0fab51ed31473e9e7d877",
+        "sha256": "14yk56l6w29xaf5x3xk27vw1riyyspn0fwd1dxdn3qdvzzrg7alk",
+        "type": "tarball",
+        "url": "https://github.com/golang/tools/archive/0abbfa5d31cd6db879f0fab51ed31473e9e7d877.tar.gz",
+        "url_template": "https://github.com/<owner>/<repo>/archive/<rev>.tar.gz"
+    }
+}

nix/sources.nix

@@ -0,0 +1,134 @@
+# This file has been generated by Niv.
+
+let
+
+  #
+  # The fetchers. fetch_<type> fetches specs of type <type>.
+  #
+
+  fetch_file = pkgs: spec:
+    if spec.builtin or true then
+      builtins_fetchurl { inherit (spec) url sha256; }
+    else
+      pkgs.fetchurl { inherit (spec) url sha256; };
+
+  fetch_tarball = pkgs: spec:
+    if spec.builtin or true then
+      builtins_fetchTarball { inherit (spec) url sha256; }
+    else
+      pkgs.fetchzip { inherit (spec) url sha256; };
+
+  fetch_git = spec:
+    builtins.fetchGit { url = spec.repo; inherit (spec) rev ref; };
+
+  fetch_builtin-tarball = spec:
+    builtins.trace
+      ''
+        WARNING:
+          The niv type "builtin-tarball" will soon be deprecated. You should
+          instead use `builtin = true`.
+
+          $ niv modify <package> -a type=tarball -a builtin=true
+      ''
+      builtins_fetchTarball { inherit (spec) url sha256; };
+
+  fetch_builtin-url = spec:
+    builtins.trace
+      ''
+        WARNING:
+          The niv type "builtin-url" will soon be deprecated. You should
+          instead use `builtin = true`.
+
+          $ niv modify <package> -a type=file -a builtin=true
+      ''
+      (builtins_fetchurl { inherit (spec) url sha256; });
+
+  #
+  # Various helpers
+  #
+
+  # The set of packages used when specs are fetched using non-builtins.
+  mkPkgs = sources:
+    let
+      sourcesNixpkgs =
+        import (builtins_fetchTarball { inherit (sources.nixpkgs) url sha256; }) {};
+      hasNixpkgsPath = builtins.any (x: x.prefix == "nixpkgs") builtins.nixPath;
+      hasThisAsNixpkgsPath = <nixpkgs> == ./.;
+    in
+      if builtins.hasAttr "nixpkgs" sources
+      then sourcesNixpkgs
+      else if hasNixpkgsPath && ! hasThisAsNixpkgsPath then
+        import <nixpkgs> {}
+      else
+        abort
+          ''
+            Please specify either <nixpkgs> (through -I or NIX_PATH=nixpkgs=...) or
+            add a package called "nixpkgs" to your sources.json.
+          '';
+
+  # The actual fetching function.
+  fetch = pkgs: name: spec:
+
+    if ! builtins.hasAttr "type" spec then
+      abort "ERROR: niv spec ${name} does not have a 'type' attribute"
+    else if spec.type == "file" then fetch_file pkgs spec
+    else if spec.type == "tarball" then fetch_tarball pkgs spec
+    else if spec.type == "git" then fetch_git spec
+    else if spec.type == "builtin-tarball" then fetch_builtin-tarball spec
+    else if spec.type == "builtin-url" then fetch_builtin-url spec
+    else
+      abort "ERROR: niv spec ${name} has unknown type ${builtins.toJSON spec.type}";
+
+  # Ports of functions for older nix versions
+
+  # a Nix version of mapAttrs if the built-in doesn't exist
+  mapAttrs = builtins.mapAttrs or (
+    f: set: with builtins;
+    listToAttrs (map (attr: { name = attr; value = f attr set.${attr}; }) (attrNames set))
+  );
+
+  # fetchTarball version that is compatible between all the versions of Nix
+  builtins_fetchTarball = { url, sha256 }@attrs:
+    let
+      inherit (builtins) lessThan nixVersion fetchTarball;
+    in
+      if lessThan nixVersion "1.12" then
+        fetchTarball { inherit url; }
+      else
+        fetchTarball attrs;
+
+  # fetchurl version that is compatible between all the versions of Nix
+  builtins_fetchurl = { url, sha256 }@attrs:
+    let
+      inherit (builtins) lessThan nixVersion fetchurl;
+    in
+      if lessThan nixVersion "1.12" then
+        fetchurl { inherit url; }
+      else
+        fetchurl attrs;
+
+  # Create the final "sources" from the config
+  mkSources = config:
+    mapAttrs (
+      name: spec:
+        if builtins.hasAttr "outPath" spec
+        then abort
+          "The values in sources.json should not have an 'outPath' attribute"
+        else
+          spec // { outPath = fetch config.pkgs name spec; }
+    ) config.sources;
+
+  # The "config" used by the fetchers
+  mkConfig =
+    { sourcesFile ? ./sources.json
+    , sources ? builtins.fromJSON (builtins.readFile sourcesFile)
+    , pkgs ? mkPkgs sources
+    }: rec {
+      # The sources, i.e. the attribute set of spec name to spec
+      inherit sources;
+
+      # The "pkgs" (evaluated nixpkgs) to use for e.g. non-builtin fetchers
+      inherit pkgs;
+    };
+in
+mkSources (mkConfig {}) // { __functor = _: settings: mkSources (mkConfig settings); }

pkgs/gopls/default.nix

@@ -1,18 +1,11 @@
-{ pkgs ? import <nixpkgs> { } }:
+{ sources ? import ../../nix/sources.nix, pkgs ? import sources.nixpkgs { } }:
+with pkgs;
 let
-  repo = pkgs.fetchFromGitHub {
+  out = buildGoPackage {
-    owner = "golang";
-    repo = "tools";
-    rev = "1ace956b0e17ff85a6f9bdf6973af28a26234113";
-    hash = "sha256:1fdhfil59w1nvz23x1qsvlpwl3yilifx6lvimnlg9r3fbzmhmqjh";
-  };
-
-  out = pkgs.buildGoPackage {
     name = "gopls-git";
     goPackagePath = "golang.org/x/tools";
-    src = repo;
+    src = sources.tools;
     goDeps = ./deps.nix;
-    modSha256 = "sha256:07gdrkdsaj78f9b6aigxqf0j46km5s39m1aswj10aj5bwdd9klid";
     subPackages = [ "gopls" ];
   };
 in out

pkgs/moonplus/default.nix

@@ -1,18 +1,11 @@
-{ pkgs ? import <nixpkgs> { } }:
+{ sources ? import ../../nix/sources.nix, pkgs ? import sources.nixpkgs { } }:
 with pkgs;
 let
-  repo = fetchFromGitHub {
-    owner = "pigpigyyy";
-    repo = "MoonPlus";
-    rev = "2e50c15bfe67d4709880a0377d37fca191be2f3e";
-    sha256 = "0h4kh20qi457mbwi4v7apji4kxqi8razys4aqp4z5v9d7zy0d0zz";
-  };
-
   defaultAttrs = {
     builder = ./builder.sh;
     baseInputs = [];
-    src = repo;
+    src = sources.MoonPlus;
-    version = "HEAD-2e50c15";
+    version = "HEAD";
     name = "MoonPlus";
     system = builtins.currentSystem;