Eliminate mixed Nixpkgs

There were two Nixpkgs inputs, with one being used solely to get a particular version of Stack. This now “compromises”
on the same release of Nixpkgs as used for Stack, but from the haskell.nix project to have a consistent package set.

There are also a few other version bumps here (because once you change an uncached input, you might as well upgrade everything):

- bump LTS to 22.43 (GHC 9.6.6 from 9.6.5)
- bump HLS to 2.9 (this is now transitively included via the haskell.nix input)
- bump hpack to 0.36.0 (this is actually the minimum bound for the
  version of Stack we use, so the previous setting was inconsistent)

.vscode/settings.json

@@ -1,7 +1,7 @@
 {
   "haskell.toolchain": {
     "cabal": "3.10.3.0",
-    "hls": "2.8.0.0",
+    "hls": "2.9.0.0",
     "stack": "2.15.7"
   }
 }

flake.nix

@@ -8,16 +8,14 @@
 
   inputs = {
     haskellNix.url = "github:input-output-hk/haskell.nix";
-    nixpkgs-haskellNix.follows = "haskellNix/nixpkgs-unstable";
-    nixpkgs-release.url = "github:NixOS/nixpkgs/release-24.05";
+    nixpkgs.follows = "haskellNix/nixpkgs-2405";
     flake-utils.url = "github:numtide/flake-utils";
   };
 
   outputs = {
     self,
     haskellNix,
-    nixpkgs-haskellNix,
-    nixpkgs-release,
+    nixpkgs,
     flake-utils,
   }:
     flake-utils.lib.eachSystem [
@@ -28,32 +26,32 @@
     (system: let
       ## It’s much easier to read from a JSON file than to have JSON import from some other file, so we extract some
       ## configuration from the VS Code settings to avoid duplication.
-      vscodeSettings = nixpkgs-release.lib.importJSON ./.vscode/settings.json;
+      vscodeSettings = nixpkgs.lib.importJSON ./.vscode/settings.json;
       versions =
         vscodeSettings."haskell.toolchain"
         ## There are some things we want to pin that the VS Code Haskell extension doesn’t let us control.
         // {
-        hpack = "0.35.2";
-        ormolu = "0.7.2.0";
-      };
-      pkgs = import nixpkgs-haskellNix {
+          hpack = "0.36.0";
+          ormolu = "0.7.2.0";
+        };
+      pkgs = import nixpkgs {
         inherit system;
         inherit (haskellNix) config;
         overlays = [
           haskellNix.overlay
-          (import ./nix/dependencies.nix {inherit nixpkgs-release;})
+          (import ./nix/dependencies.nix)
         ];
       };
       unison-project = import ./nix/unison-project.nix {
-        inherit (nixpkgs-haskellNix) lib;
+        inherit (nixpkgs) lib;
         inherit (pkgs) haskell-nix;
       };
       haskell-nix-flake = import ./nix/haskell-nix-flake.nix {
         inherit pkgs unison-project versions;
-        inherit (nixpkgs-haskellNix) lib;
+        inherit (nixpkgs) lib;
       };
       renameAttrs = fn:
-        nixpkgs-haskellNix.lib.mapAttrs' (name: value: {
+        nixpkgs.lib.mapAttrs' (name: value: {
           inherit value;
           name = fn name;
         });
@@ -71,11 +69,10 @@
             all = pkgs.symlinkJoin {
               name = "all";
               paths = let
-                all-other-packages =
-                  builtins.attrValues (builtins.removeAttrs self.packages."${system}" [
-                    "all"
-                    "docker-ucm" # this package doesn’t produce a directory
-                  ]);
+                all-other-packages = builtins.attrValues (builtins.removeAttrs self.packages."${system}" [
+                  "all"
+                  "docker-ucm" # this package doesn’t produce a directory
+                ]);
                 devshell-inputs =
                   builtins.concatMap
                   (devShell: devShell.buildInputs ++ devShell.nativeBuildInputs)

nix/dependencies.nix

@@ -1,21 +1,13 @@
-{nixpkgs-release}: final: prev: let
-  pinned-pkgs = import nixpkgs-release {inherit (final) system;};
-in {
-  stack = pinned-pkgs.stack;
-
+final: prev: {
   ## See https://docs.haskellstack.org/en/stable/nix_integration/#supporting-both-nix-and-non-nix-developers for an
-  ## explanation of this package.
-  stack-wrapped = final.symlinkJoin {
-    name = "stack"; # will be available as the usual `stack` in terminal
-    paths = [final.stack];
+  ## explanation of this derivation.
+  stack = final.symlinkJoin {
+    inherit (prev.stack) version;
+    name = "stack";
+    paths = [prev.stack];
     buildInputs = [final.makeWrapper];
     postBuild = ''
-      wrapProgram $out/bin/stack \
-        --add-flags "\
-          --no-nix \
-          --system-ghc \
-          --no-install-ghc \
-        "
+      wrapProgram $out/bin/stack --add-flags "--no-nix --system-ghc --no-install-ghc"
     '';
   };
 }

nix/haskell-nix-flake.nix

@@ -35,7 +35,7 @@
           pkgs.gettext # for envsubst, used by unison-src/builtin-tests/interpreter-tests.sh
           pkgs.hpack
           pkgs.pkg-config
-          pkgs.stack-wrapped
+          pkgs.stack
         ];
       # workaround for https://gitlab.haskell.org/ghc/ghc/-/issues/11042
       shellHook = ''
@@ -45,7 +45,6 @@
         (args.tools or {})
         // {
           cabal = {version = versions.cabal;};
-          ormolu = {version = versions.ormolu;};
           haskell-language-server = {
             version = versions.hls;
             modules = [
@@ -64,6 +63,7 @@
               constraints: ormolu == ${versions.ormolu}
             '';
           };
+          ormolu = {version = versions.ormolu;};
         };
     };
 

stack.yaml

@@ -50,7 +50,7 @@ packages:
   - unison-syntax
   - yaks/easytest
 
-resolver: lts-22.26
+resolver: lts-22.43
 
 extra-deps:
   # This custom Haskeline alters ANSI rendering on Windows.

stack.yaml.lock

@@ -59,7 +59,7 @@ packages:
     hackage: network-udp-0.0.0@sha256:408d2d4fa1a25e49e95752ee124cca641993404bb133ae10fb81daef22d876ae,1075
 snapshots:
 - completed:
-    sha256: 8e7996960d864443a66eb4105338bbdd6830377b9f6f99cd5527ef73c10c01e7
-    size: 719128
-    url: https://raw.githubusercontent.com/commercialhaskell/stackage-snapshots/master/lts/22/26.yaml
-  original: lts-22.26
+    sha256: 08bd13ce621b41a8f5e51456b38d5b46d7783ce114a50ab604d6bbab0d002146
+    size: 720271
+    url: https://raw.githubusercontent.com/commercialhaskell/stackage-snapshots/master/lts/22/43.yaml
+  original: lts-22.43