Stop using flakes

It was requiring nixUnstable or a compatibility shim, while not providing much in this project.

.github/workflows/build.yaml

@@ -10,17 +10,9 @@ jobs:
     runs-on: ${{ matrix.os }}
     steps:
     - uses: actions/checkout@v2
-      with:
-          # Nix Flakes doesn't work on shallow clones
-          fetch-depth: 0
     - uses: cachix/install-nix-action@v12
-      with:
-        install_url: https://github.com/numtide/nix-flakes-installer/releases/download/nix-2.4pre20201221_9fab14a/install
-        extra_nix_config: |
-          experimental-features = nix-command flakes
     - uses: cachix/cachix-action@v8
       with:
         name: utdemir
         signingKey: '${{ secrets.CACHIX_SIGNING_KEY }}'
-    - run: nix build
-    - run: nix develop --command 'echo' 'ok.'
+    - run: nix-build

.gitignore

@@ -1,5 +1,3 @@
-*.lock
-
 # nix
 result
 result-*

README.md

@@ -17,16 +17,8 @@ nix-env -i nix-tree
 
 To run the current development version:
 
-* With flakes:
-
 ```
-nix run github:utdemir/nix-tree
-```
-
-* Without flakes:
-
-```
-nix-shell -I nix-tree=https://github.com/utdemir/nix-tree/archive/refs/heads/main.zip -p '(import <nix-tree>).default'  
+nix-shell -p '(import (builtins.fetchTarball "https://github.com/utdemir/nix-tree/archive/main.tar.gz") {}).nix-tree' --run nix-tree
 ```
 
 ## Usage
@@ -78,7 +70,7 @@ nix-build '<nixpkgs>' -A openssl.all --no-out-link | xargs -o nix-tree
 
 All contributions, issues and feature requests are welcome.
 
-To hack on it, simply run `nix-shell` (or `nix develop`) and use `cabal` as usual. Please run `./format.sh` before sending a PR.
+To hack on it, simply run `nix-shell` and use `cabal` as usual. Please run `./format.sh` before sending a PR.
 
 ## Related tools
 

default.nix

@@ -1,3 +1,51 @@
-(import (fetchTarball https://github.com/edolstra/flake-compat/archive/master.tar.gz) {
-  src = ./.;
-}).defaultNix
+let
+  sources = import ./nix/sources.nix;
+in
+
+{ pkgs ? import sources.nixpkgs { } }:
+
+let
+  nix-filter = import sources.nix-filter;
+  src = nix-filter {
+    root = ./.;
+    include = with nix-filter; [
+      (and
+        (or_ (inDirectory "src") (inDirectory "test"))
+        (or_ isDirectory (matchExt "hs")))
+      ./nix-tree.cabal
+      ./README.md
+      ./CHANGELOG.md
+      ./LICENSE
+    ];
+  };
+
+  myHaskellPackages = pkgs.haskellPackages.override {
+    overrides = hself: hsuper: {
+      "nix-tree" =
+        hself.callCabal2nix "nix-tree" src { };
+    };
+  };
+
+  shell = myHaskellPackages.shellFor {
+    packages = p: [
+      p."nix-tree"
+    ];
+    buildInputs = [
+      myHaskellPackages.haskell-language-server
+      pkgs.haskellPackages.cabal-install
+      pkgs.haskellPackages.ghcid
+      pkgs.haskellPackages.ormolu
+      pkgs.haskellPackages.hlint
+      pkgs.niv
+      pkgs.nixpkgs-fmt
+    ];
+    withHoogle = false;
+  };
+
+in
+{
+  inherit shell;
+  "nix-tree" =
+    pkgs.haskell.lib.justStaticExecutables (myHaskellPackages."nix-tree");
+}
+

flake.lock

@@ -1,44 +0,0 @@
-{
-  "nodes": {
-    "flake-utils": {
-      "locked": {
-        "lastModified": 1614513358,
-        "narHash": "sha256-LakhOx3S1dRjnh0b5Dg3mbZyH0ToC9I8Y2wKSkBaTzU=",
-        "owner": "numtide",
-        "repo": "flake-utils",
-        "rev": "5466c5bbece17adaab2d82fae80b46e807611bf3",
-        "type": "github"
-      },
-      "original": {
-        "owner": "numtide",
-        "ref": "master",
-        "repo": "flake-utils",
-        "type": "github"
-      }
-    },
-    "nixpkgs": {
-      "locked": {
-        "lastModified": 1615880991,
-        "narHash": "sha256-hkI/PzSK46MXmysU0jl75QxiEm3ASogIU4PMu2mVQ2Y=",
-        "owner": "nixos",
-        "repo": "nixpkgs",
-        "rev": "f1e8b1e500f0856820187c41cf4f5202a5f9bce7",
-        "type": "github"
-      },
-      "original": {
-        "owner": "nixos",
-        "ref": "nixpkgs-unstable",
-        "repo": "nixpkgs",
-        "type": "github"
-      }
-    },
-    "root": {
-      "inputs": {
-        "flake-utils": "flake-utils",
-        "nixpkgs": "nixpkgs"
-      }
-    }
-  },
-  "root": "root",
-  "version": 7
-}

flake.nix

@@ -1,52 +0,0 @@
-{
-  inputs = {
-    nixpkgs.url = "github:nixos/nixpkgs/nixpkgs-unstable";
-    flake-utils.url = "github:numtide/flake-utils/master";
-  };
-
-  description = "Interactively browse the dependency graph of your Nix derivations.";
-
-  outputs = { self, nixpkgs, flake-utils }:
-    let
-      overlay = self: super: {
-        haskellPackages = super.haskellPackages.override {
-          overrides = hself: hsuper: {
-            nix-tree =
-              hself.callCabal2nix
-                "nix-tree"
-                (self.lib.cleanSourceWith {
-                  filter = path: _type:
-                    !(builtins.elem (builtins.baseNameOf path) [ "asciicast.sh" "flake.nix" ]);
-                  src = ./.;
-                })
-                { };
-          };
-        };
-        nix-tree =
-          self.haskell.lib.justStaticExecutables
-            self.haskellPackages.nix-tree;
-      };
-    in
-    { inherit overlay; } // flake-utils.lib.eachDefaultSystem (system:
-      let
-        pkgs = import nixpkgs { inherit system; overlays = [ overlay ]; };
-      in
-      {
-        defaultPackage = pkgs.nix-tree;
-        devShell = pkgs.haskellPackages.shellFor {
-          packages = p: [
-            p."nix-tree"
-          ];
-          buildInputs = with pkgs.haskellPackages; [
-            cabal-install
-            haskell-language-server
-            ghcid
-            ormolu
-            hlint
-            pkgs.nixpkgs-fmt
-          ];
-          withHoogle = false;
-        };
-      }
-    );
-}

format.sh

@@ -4,4 +4,4 @@ set -o xtrace
 set -o errexit
 
 fd -e hs -X ormolu -o -XTypeApplications --mode inplace {}
-nixpkgs-fmt flake.nix
+nixpkgs-fmt default.nix

nix/sources.json

@@ -0,0 +1,26 @@
+{
+    "nix-filter": {
+        "branch": "master",
+        "description": "a small self-container source filtering lib",
+        "homepage": "",
+        "owner": "numtide",
+        "repo": "nix-filter",
+        "rev": "3c9e33ed627e009428197b07216613206f06ed80",
+        "sha256": "19w142crrkywxynmyw4rhz4nglrg64yjawfkw3j91qwkwbfjds84",
+        "type": "tarball",
+        "url": "https://github.com/numtide/nix-filter/archive/3c9e33ed627e009428197b07216613206f06ed80.tar.gz",
+        "url_template": "https://github.com/<owner>/<repo>/archive/<rev>.tar.gz"
+    },
+    "nixpkgs": {
+        "branch": "nixpkgs-unstable",
+        "description": "Nix Packages collection",
+        "homepage": "",
+        "owner": "nixos",
+        "repo": "nixpkgs",
+        "rev": "4e55c8bc6703699a016093e9bf745bd713bcdfba",
+        "sha256": "0p2bv7sdvs19vqqkhv99n7llrp7ky6wgiqxjcg6k70a0z35rf793",
+        "type": "tarball",
+        "url": "https://github.com/nixos/nixpkgs/archive/4e55c8bc6703699a016093e9bf745bd713bcdfba.tar.gz",
+        "url_template": "https://github.com/<owner>/<repo>/archive/<rev>.tar.gz"
+    }
+}

nix/sources.nix

@@ -0,0 +1,174 @@
+# This file has been generated by Niv.
+
+let
+
+  #
+  # The fetchers. fetch_<type> fetches specs of type <type>.
+  #
+
+  fetch_file = pkgs: name: spec:
+    let
+      name' = sanitizeName name + "-src";
+    in
+      if spec.builtin or true then
+        builtins_fetchurl { inherit (spec) url sha256; name = name'; }
+      else
+        pkgs.fetchurl { inherit (spec) url sha256; name = name'; };
+
+  fetch_tarball = pkgs: name: spec:
+    let
+      name' = sanitizeName name + "-src";
+    in
+      if spec.builtin or true then
+        builtins_fetchTarball { name = name'; inherit (spec) url sha256; }
+      else
+        pkgs.fetchzip { name = name'; inherit (spec) url sha256; };
+
+  fetch_git = name: spec:
+    let
+      ref =
+        if spec ? ref then spec.ref else
+          if spec ? branch then "refs/heads/${spec.branch}" else
+            if spec ? tag then "refs/tags/${spec.tag}" else
+              abort "In git source '${name}': Please specify `ref`, `tag` or `branch`!";
+    in
+      builtins.fetchGit { url = spec.repo; inherit (spec) rev; inherit ref; };
+
+  fetch_local = spec: spec.path;
+
+  fetch_builtin-tarball = name: throw
+    ''[${name}] The niv type "builtin-tarball" is deprecated. You should instead use `builtin = true`.
+        $ niv modify ${name} -a type=tarball -a builtin=true'';
+
+  fetch_builtin-url = name: throw
+    ''[${name}] The niv type "builtin-url" will soon be deprecated. You should instead use `builtin = true`.
+        $ niv modify ${name} -a type=file -a builtin=true'';
+
+  #
+  # Various helpers
+  #
+
+  # https://github.com/NixOS/nixpkgs/pull/83241/files#diff-c6f540a4f3bfa4b0e8b6bafd4cd54e8bR695
+  sanitizeName = name:
+    (
+      concatMapStrings (s: if builtins.isList s then "-" else s)
+        (
+          builtins.split "[^[:alnum:]+._?=-]+"
+            ((x: builtins.elemAt (builtins.match "\\.*(.*)" x) 0) name)
+        )
+    );
+
+  # The set of packages used when specs are fetched using non-builtins.
+  mkPkgs = sources: system:
+    let
+      sourcesNixpkgs =
+        import (builtins_fetchTarball { inherit (sources.nixpkgs) url sha256; }) { inherit system; };
+      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 name spec
+    else if spec.type == "tarball" then fetch_tarball pkgs name spec
+    else if spec.type == "git" then fetch_git name spec
+    else if spec.type == "local" then fetch_local spec
+    else if spec.type == "builtin-tarball" then fetch_builtin-tarball name
+    else if spec.type == "builtin-url" then fetch_builtin-url name
+    else
+      abort "ERROR: niv spec ${name} has unknown type ${builtins.toJSON spec.type}";
+
+  # If the environment variable NIV_OVERRIDE_${name} is set, then use
+  # the path directly as opposed to the fetched source.
+  replace = name: drv:
+    let
+      saneName = stringAsChars (c: if isNull (builtins.match "[a-zA-Z0-9]" c) then "_" else c) name;
+      ersatz = builtins.getEnv "NIV_OVERRIDE_${saneName}";
+    in
+      if ersatz == "" then drv else
+        # this turns the string into an actual Nix path (for both absolute and
+        # relative paths)
+        if builtins.substring 0 1 ersatz == "/" then /. + ersatz else /. + builtins.getEnv "PWD" + "/${ersatz}";
+
+  # 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))
+  );
+
+  # https://github.com/NixOS/nixpkgs/blob/0258808f5744ca980b9a1f24fe0b1e6f0fecee9c/lib/lists.nix#L295
+  range = first: last: if first > last then [] else builtins.genList (n: first + n) (last - first + 1);
+
+  # https://github.com/NixOS/nixpkgs/blob/0258808f5744ca980b9a1f24fe0b1e6f0fecee9c/lib/strings.nix#L257
+  stringToCharacters = s: map (p: builtins.substring p 1 s) (range 0 (builtins.stringLength s - 1));
+
+  # https://github.com/NixOS/nixpkgs/blob/0258808f5744ca980b9a1f24fe0b1e6f0fecee9c/lib/strings.nix#L269
+  stringAsChars = f: s: concatStrings (map f (stringToCharacters s));
+  concatMapStrings = f: list: concatStrings (map f list);
+  concatStrings = builtins.concatStringsSep "";
+
+  # https://github.com/NixOS/nixpkgs/blob/8a9f58a375c401b96da862d969f66429def1d118/lib/attrsets.nix#L331
+  optionalAttrs = cond: as: if cond then as else {};
+
+  # fetchTarball version that is compatible between all the versions of Nix
+  builtins_fetchTarball = { url, name ? null, sha256 }@attrs:
+    let
+      inherit (builtins) lessThan nixVersion fetchTarball;
+    in
+      if lessThan nixVersion "1.12" then
+        fetchTarball ({ inherit url; } // (optionalAttrs (!isNull name) { inherit name; }))
+      else
+        fetchTarball attrs;
+
+  # fetchurl version that is compatible between all the versions of Nix
+  builtins_fetchurl = { url, name ? null, sha256 }@attrs:
+    let
+      inherit (builtins) lessThan nixVersion fetchurl;
+    in
+      if lessThan nixVersion "1.12" then
+        fetchurl ({ inherit url; } // (optionalAttrs (!isNull name) { inherit name; }))
+      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 = replace name (fetch config.pkgs name spec); }
+    ) config.sources;
+
+  # The "config" used by the fetchers
+  mkConfig =
+    { sourcesFile ? if builtins.pathExists ./sources.json then ./sources.json else null
+    , sources ? if isNull sourcesFile then {} else builtins.fromJSON (builtins.readFile sourcesFile)
+    , system ? builtins.currentSystem
+    , pkgs ? mkPkgs sources system
+    }: 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); }

shell.nix

@@ -1,3 +1 @@
-(import (fetchTarball https://github.com/edolstra/flake-compat/archive/master.tar.gz) {
-  src = ./.;
-}).shellNix
+(import ./. {}).shell