buck2: Use nushell for the updateScript

pkgs/by-name/bu/buck2/hashes.json

···
 {
-  "rust-project-aarch64-linux": "sha256-Pm5lEIu0hzI5BuA/LuTKjBP8S63jiz1oSB0g9tSETGU=",
-  "buck2-aarch64-linux": "sha256-Gn/Q2P0Fs93SbOawhzv8Z9DgbrIUlQ+9E3PyCNsV1pk=",
-  "buck2-aarch64-darwin": "sha256-XtGs7g64s76AYhpFDbqSuSlblRauxJM0PaAk1MNNgxA=",
-  "buck2-x86_64-linux": "sha256-gVOho7p25okvAV8OqXppdtwOOEzqH7VWcJBT4l5CT2U=",
-  "rust-project-x86_64-darwin": "sha256-ePawMIfltPRK3mJJxI1BvGs6b2vIcgWzW2XTJykUsdI=",
+  "x86_64-linux": {
+    "buck2": "sha256-gVOho7p25okvAV8OqXppdtwOOEzqH7VWcJBT4l5CT2U=",
+    "rust-project": "sha256-HKctvCiXyGFzfHfB3Qj6qR2p46i5vaaZgPg2J827ou4="
+  },
+  "x86_64-darwin": {
+    "buck2": "sha256-wHk/tJJbupMsrcmXXNVXurfLY2TOSssMnuTZ7LNjASY=",
+    "rust-project": "sha256-ePawMIfltPRK3mJJxI1BvGs6b2vIcgWzW2XTJykUsdI="
+  },
+  "aarch64-linux": {
+    "buck2": "sha256-Gn/Q2P0Fs93SbOawhzv8Z9DgbrIUlQ+9E3PyCNsV1pk=",
+    "rust-project": "sha256-Pm5lEIu0hzI5BuA/LuTKjBP8S63jiz1oSB0g9tSETGU="
+  },
+  "aarch64-darwin": {
+    "buck2": "sha256-XtGs7g64s76AYhpFDbqSuSlblRauxJM0PaAk1MNNgxA=",
+    "rust-project": "sha256-CkyLLv41iJTKHVB0e355ZO2MV7NzQeiF1gtWEGF5oAY="
+  },
   "version": "2025-08-15",
-  "rust-project-x86_64-linux": "sha256-HKctvCiXyGFzfHfB3Qj6qR2p46i5vaaZgPg2J827ou4=",
-  "buck2-x86_64-darwin": "sha256-wHk/tJJbupMsrcmXXNVXurfLY2TOSssMnuTZ7LNjASY=",
-  "rust-project-aarch64-darwin": "sha256-CkyLLv41iJTKHVB0e355ZO2MV7NzQeiF1gtWEGF5oAY=",
-  "prelude_fod": "sha256-cyuOMi8x8q9gd6p1obnYYDVPxyONZ+y41AFXvSbUjC0=",
-  "_comment": "Generated by buck2 update.sh",
-  "prelude_git": "892cb85f5fc3258c7e4f89a836821ec4b8c7ee44"
+  "preludeGit": "892cb85f5fc3258c7e4f89a836821ec4b8c7ee44",
+  "preludeFod": "sha256-cyuOMi8x8q9gd6p1obnYYDVPxyONZ+y41AFXvSbUjC0="
 }

pkgs/by-name/bu/buck2/package.nix

···
   # procued by GitHub Actions. this also includes the hash for a download of a
   # compatible buck2-prelude
   buildHashes = builtins.fromJSON (builtins.readFile ./hashes.json);
+  archHashes = buildHashes.${stdenv.hostPlatform.system};
 
   # map our platform name to the rust toolchain suffix
-  # NOTE (aseipp): must be synchronized with update.sh!
+  # NOTE (aseipp): must be synchronized with update.nu!
   platform-suffix =
     {
       x86_64-darwin = "x86_64-apple-darwin";
···
       x86_64-linux = "x86_64-unknown-linux-gnu";
       aarch64-linux = "aarch64-unknown-linux-gnu";
     }
-    ."${stdenv.hostPlatform.system}";
+    .${stdenv.hostPlatform.system};
 in
 stdenv.mkDerivation (finalAttrs: {
   pname = "buck2";
···
     # zstd-compressed
     (fetchurl {
       url = "https://github.com/facebook/buck2/releases/download/${lib.removePrefix "unstable-" finalAttrs.version}/buck2-${platform-suffix}.zst";
-      hash = buildHashes."buck2-${stdenv.hostPlatform.system}";
+      hash = archHashes.buck2;
     })
     # rust-project, which is used to provide IDE integration Buck2 Rust projects,
     # is part of the official distribution
     (fetchurl {
       url = "https://github.com/facebook/buck2/releases/download/${lib.removePrefix "unstable-" finalAttrs.version}/rust-project-${platform-suffix}.zst";
-      hash = buildHashes."rust-project-${stdenv.hostPlatform.system}";
+      hash = archHashes.rust-project;
     })
   ];
 
···
     # for downstream consumers to use when they need to automate any kind of
     # tooling
     prelude = fetchurl {
-      url = "https://github.com/facebook/buck2-prelude/archive/${buildHashes.prelude-git}.tar.gz";
-      hash = buildHashes.prelude-fod;
+      url = "https://github.com/facebook/buck2-prelude/archive/${buildHashes.preludeGit}.tar.gz";
+      hash = buildHashes.preludeFod;
     };
 
-    updateScript = ./update.sh;
+    updateScript = ./update.nu;
   };
 
   meta = {

pkgs/by-name/bu/buck2/update.nu

···
+#!/usr/bin/env nix-shell
+#! nix-shell -I ./.
+#! nix-shell -i nu
+#! nix-shell -p nushell nix
+
+const ARCHES = [
+  { name: "x86_64-linux", target: "x86_64-unknown-linux-gnu" },
+  { name: "x86_64-darwin", target: "x86_64-apple-darwin" },
+  { name: "aarch64-linux", target: "aarch64-unknown-linux-gnu" },
+  { name: "aarch64-darwin", target: "aarch64-apple-darwin" },
+];
+
+const MANIFEST = "pkgs/by-name/bu/buck2/hashes.json"
+
+def main [] {
+  let version = http get "https://api.github.com/repos/facebook/buck2/releases"
+    | sort-by -r created_at
+    | where prerelease == true and name != "latest"
+    | first
+    | get name
+
+  let preludeHash = http get $"https://github.com/facebook/buck2/releases/download/($version)/prelude_hash" | decode | str trim
+  let preludeFod = run-external "nix" "--extra-experimental-features" "nix-command" "store" "prefetch-file" "--json" $"https://github.com/facebook/buck2-prelude/archive/($preludeHash).tar.gz" | from json | get hash
+
+  print $"Newest version: ($version)"
+  print $"Newest prelude hash: ($preludeHash)"
+
+  let hashes = $ARCHES | par-each {
+    |arch|
+
+    {
+      $arch.name: {
+        "buck2": (run-external "nix" "--extra-experimental-features" "nix-command" "store" "prefetch-file" "--json" $"https://github.com/facebook/buck2/releases/download/($version)/buck2-($arch.target).zst" | from json | get hash),
+        "rust-project": (run-external "nix" "--extra-experimental-features" "nix-command" "store" "prefetch-file" "--json" $"https://github.com/facebook/buck2/releases/download/($version)/rust-project-($arch.target).zst" | from json | get hash),
+      }
+    }
+  } | reduce { |val, accum| $accum | merge $val }
+
+  let new_manifest = $hashes
+    | insert "version" $version
+    | insert "preludeGit" $preludeHash
+    | insert "preludeFod" $preludeFod
+
+  $new_manifest
+  | to json
+  | append "\n"
+  | str join
+  | save -f $MANIFEST
+}

pkgs/by-name/bu/buck2/update.sh

···
-#!/usr/bin/env nix-shell
-#! nix-shell -I nixpkgs=./.
-#! nix-shell -i bash
-#! nix-shell -p curl jq common-updater-scripts nix coreutils
-# shellcheck shell=bash
-set -euo pipefail
-
-VERSION=$(curl -s https://api.github.com/repos/facebook/buck2/releases \
-  | jq -r 'sort_by(.created_at) | reverse |
-           (map
-             (select ((.prerelease == true) and (.name != "latest"))) |
-             first
-           ) | .name')
-PRELUDE_HASH=$(curl -sLo - "https://github.com/facebook/buck2/releases/download/${VERSION}/prelude_hash")
-PRELUDE_DL_URL="https://github.com/facebook/buck2-prelude/archive/${PRELUDE_HASH}.tar.gz"
-
-echo "Latest buck2 prerelease: $VERSION"
-echo "Compatible buck2-prelude hash: $PRELUDE_HASH"
-
-ARCHS=(
-    "x86_64-linux:x86_64-unknown-linux-gnu"
-    "x86_64-darwin:x86_64-apple-darwin"
-    "aarch64-linux:aarch64-unknown-linux-gnu"
-    "aarch64-darwin:aarch64-apple-darwin"
-)
-
-NFILE=pkgs/by-name/bu/buck2/package.nix
-HFILE=pkgs/by-name/bu/buck2/hashes.json
-
-declare -A outputJson=()
-outputJson["version"]="$VERSION"
-outputJson["prelude_git"]="$PRELUDE_HASH"
-outputJson["prelude_fod"]="$(nix --extra-experimental-features nix-command store prefetch-file --json "$PRELUDE_DL_URL" | jq -r .hash)"
-
-for arch in "${ARCHS[@]}"; do
-    IFS=: read -r arch_name arch_target <<< "$arch"
-    outputJson["buck2-$arch_name"]="$(nix --extra-experimental-features nix-command store prefetch-file --json "https://github.com/facebook/buck2/releases/download/${VERSION}/buck2-${arch_target}.zst" | jq -r .hash)"
-
-    outputJson["rust-project-$arch_name"]="$(nix --extra-experimental-features nix-command store prefetch-file --json "https://github.com/facebook/buck2/releases/download/${VERSION}/rust-project-${arch_target}.zst" | jq -r .hash)"
-done
-
-outputJson["_comment"]="Generated by buck2 update.sh"
-jq -n 'def _nwise($n): def nw: if length <= $n then . else .[0:$n] , (.[$n:] | nw) end; nw; [$ARGS.positional | _nwise(2) | {(.[0]): .[1]}] | add' --args "${outputJson[@]@k}" > "$HFILE"
-
-echo "Done; wrote $HFILE and updated version in $NFILE."