elixir_ls: add update script

pkgs/development/beam-modules/default.nix

@@ -76,7 +76,7 @@ let
         debugInfo = true;
       };
 
-      elixir_ls = callPackage ./elixir_ls.nix { inherit elixir fetchMixDeps mixRelease; };
+      elixir_ls = callPackage ./elixir-ls { inherit elixir fetchMixDeps mixRelease; };
 
       lfe = lfe_1_3;
       lfe_1_3 = lib'.callLFE ../interpreters/lfe/1.3.nix { inherit erlang buildRebar3 buildHex; };

pkgs/development/beam-modules/elixir-ls/default.nix

@@ -68,4 +68,5 @@ mixRelease rec {
     platforms = platforms.unix;
     maintainers = teams.beam.members;
   };
+  passthru.updateScript = ./update.sh;
 }

pkgs/development/beam-modules/elixir-ls/update.sh

@@ -0,0 +1,32 @@
+#!/usr/bin/env nix-shell
+#! nix-shell -i oil -p jq sd nix-prefetch-github ripgrep
+
+# TODO set to `verbose` or `extdebug` once implemented in oil
+shopt --set xtrace
+
+var directory = $(dirname $0 | xargs realpath)
+var owner = "elixir-lsp"
+var repo = "elixir-ls"
+var latest_rev = $(curl -q https://api.github.com/repos/${owner}/${repo}/releases/latest | \
+  jq -r '.tag_name')
+var latest_version = $(echo $latest_rev | sd 'v' '')
+var current_version = $(nix-instantiate -A elixir_ls.version --eval --json | jq -r)
+if ("$latest_version" == "$current_version") {
+  echo "elixir-ls is already up-to-date"
+  return 0
+} else {
+  var tarball_meta = $(nix-prefetch-github $owner $repo --rev "$latest_rev")
+  var tarball_hash = "sha256-$(echo $tarball_meta | jq -r '.sha256')"
+  var sha256s = $(rg '"sha256-.+"' $directory/default.nix | sd '.+"(.+)";' '$1' )
+  echo $sha256s | read --line :github_sha256
+  echo $sha256s | tail -n 1 | read --line :old_mix_sha256
+  sd 'version = ".+"' "version = \"$latest_version\"" "$directory/default.nix"
+  sd "sha256 = \"$github_sha256\"" "sha256 = \"$tarball_hash\"" "$directory/default.nix"
+  sd "sha256 = \"$old_mix_sha256\"" "sha256 = \"\"" "$directory/default.nix"
+
+  var new_mix_hash = $(nix-build -A elixir_ls.mixFodDeps 2>&1 | \
+    tail -n 1 | \
+    sd '\s+got:\s+' '')
+
+  sd "sha256 = \"\"" "sha256 = \"$new_mix_hash\"" "$directory/default.nix"
+}