feat: add LSP for Elixir

lsp/elixir.lua

@@ -0,0 +1,22 @@
+---@type vim.lsp.Config
+--- 'root_dir' is chosen like this:
+--- if two or more directories containing `mix.exs` were found when searching
+--- directories upward, the second one (higher up) is chosen, with the
+--- assumption that it is the root of an umbrella app. Otherwise the directory
+--- containing the single mix.exs that was found is chosen.
+return {
+    -- cmd when installing with Mason
+    -- Had to install elixir and asdf (homebrew)
+    -- Then ran `mix local.hex` to upgrade Hex
+    cmd = { vim.env.HOME .. "/.local/share/nvim/mason/packages/elixir-ls/language_server.sh" },
+    -- cmd = { "/Users/oliver.ladner/.local/share/nvim/mason/packages/elixir-ls/language_server.sh" },
+    filetypes = { "elixir", "eelixir", "heex", "surface" },
+    root_dir = function(bufnr, on_dir)
+        local fname = vim.api.nvim_buf_get_name(bufnr)
+        local matches = vim.fs.find({ "mix.exs" }, { upward = true, limit = 2, path = fname })
+        local child_or_root_path, maybe_umbrella_path = unpack(matches)
+        local root_dir = vim.fs.dirname(maybe_umbrella_path or child_or_root_path)
+
+        on_dir(root_dir)
+    end,
+}

lua/weeheavy/prefs.lua

@@ -13,6 +13,7 @@ vim.lsp.enable({
     "bicep",
     "proselint",
     "python",
+    "elixir",
 })
 
 -- Set highlight on search