3 files changed, 30 insertions, 6 deletions
diff --git a/lua/nvim-lsp-installer/data.lua b/lua/nvim-lsp-installer/data.lua
index 264fda80..268d3aec 100644
--- a/lua/nvim-lsp-installer/data.lua
+++ b/lua/nvim-lsp-installer/data.lua
@@ -1,3 +1,5 @@
+-- TODO: rename this to functional.lua, long overdue
+
 local Data = {}
 
 ---@generic T : string
@@ -122,14 +124,16 @@ function Data.list_any(list, predicate)
     return false
 end
 
+function Data.identity(a)
+    return a
+end
+
 ---@generic T : fun(...)
 ---@param fn T
----@param cache_key_generator fun(...): string | nil
+---@param cache_key_generator (fun(...): string | nil)|nil
 ---@return T
 function Data.memoize(fn, cache_key_generator)
-    cache_key_generator = cache_key_generator or function(a)
-        return a
-    end
+    cache_key_generator = cache_key_generator or Data.identity
     local cache = {}
     return function(...)
         local key = cache_key_generator(...)
diff --git a/lua/nvim-lsp-installer/middleware.lua b/lua/nvim-lsp-installer/middleware.lua
index 7def4276..b09b51ac 100644
--- a/lua/nvim-lsp-installer/middleware.lua
+++ b/lua/nvim-lsp-installer/middleware.lua
@@ -1,6 +1,9 @@
 local util = require "lspconfig.util"
 local servers = require "nvim-lsp-installer.servers"
 local settings = require "nvim-lsp-installer.settings"
+local Data = require "nvim-lsp-installer.data"
+
+local memoize, set_of = Data.memoize, Data.set_of
 
 local M = {}
 
@@ -21,14 +24,26 @@ local function merge_in_place(t1, t2)
     return t1
 end
 
+local memoized_set = memoize(set_of)
+
+---@param server_name string
+local function should_auto_install(server_name)
+    if settings.current.automatic_installation == true then
+        return true
+    end
+    if type(settings.current.automatic_installation) == "table" then
+        return not memoized_set(settings.current.automatic_installation.exclude)[server_name]
+    end
+    return false
+end
+
 function M.register_lspconfig_hook()
     util.on_setup = util.add_hook_before(util.on_setup, function(config)
         local ok, server = servers.get_server(config.name)
         if ok then
             if server:is_installed() then
                 merge_in_place(config, server._default_options)
-            end
-            if settings.current.automatic_installation and not server:is_installed() then
+            elseif should_auto_install(server.name) then
                 server:install()
             end
         end
diff --git a/lua/nvim-lsp-installer/settings.lua b/lua/nvim-lsp-installer/settings.lua
index 44c739db..5cfdae4f 100644
--- a/lua/nvim-lsp-installer/settings.lua
+++ b/lua/nvim-lsp-installer/settings.lua
@@ -7,6 +7,11 @@ local DEFAULT_SETTINGS = {
     -- A list of servers to automatically install. Example: { "rust_analyzer", "sumneko_lua" }
     ensure_installed = {},
     -- Whether servers that are set up (via lspconfig) should be automatically installed if they're not already installed.
+    -- Can either be:
+    --   - false: Servers are not automatically installed.
+    --   - true: All servers set up via lspconfig are automatically installed.
+    --   - { exclude: string[] }: All servers set up via lspconfig, except the ones provided in the list, are automatically installed.
+    --       Example: automatic_installation = { exclude = { "rust_analyzer", "solargraph" } }
     automatic_installation = false,
     ui = {
         icons = {