Add lean4ls and improve Lean root directory search.

lua/lspconfig/lean4ls.lua

@@ -0,0 +1,32 @@
+local configs = require 'lspconfig/configs'
+local util = require 'lspconfig/util'
+
+local function find_toml(startpath)
+  return util.search_ancestors(util.path.dirname(startpath), function(path)
+    local toml_file = util.path.join(path, "leanpkg.toml")
+    if util.path.is_file(toml_file) then
+      return toml_file
+    end
+  end)
+end
+
+configs.lean4ls = {
+  default_config = {
+    cmd = {"lean4", "--server"};
+    filetypes = {"lean4"};
+    root_dir = function(fname)
+      return find_toml(fname) or util.find_git_ancestor(fname) or vim.loop.os_homedir()
+    end;
+  };
+  docs = {
+    package_json = "https://raw.githubusercontent.com/leanprover-community/vscode-lean4/master/package.json",
+    description = [[
+			The Lean 4 language server is built-in with a Lean 4 install, 
+			and can be run with, e.g., "lean4 --server".
+    ]];
+    default_config = {
+      root_dir = [[find_toml() or root_pattern(".git") or os_homedir]];
+    };
+  };
+}
+-- vim:et ts=2 sw=2

lua/lspconfig/leanls.lua

@@ -1,12 +1,21 @@
 local configs = require 'lspconfig/configs'
 local util = require 'lspconfig/util'
 
+local function find_toml(startpath)
+  return util.search_ancestors(util.path.dirname(startpath), function(path)
+    local toml_file = util.path.join(path, "leanpkg.toml")
+    if util.path.is_file(toml_file) then
+      return toml_file
+    end
+  end)
+end
+
 configs.leanls = {
   default_config = {
     cmd = {"lean-language-server", "--stdio"};
     filetypes = {"lean"};
     root_dir = function(fname)
-      return util.find_git_ancestor(fname) or vim.loop.os_homedir()
+      return find_toml(fname) or util.find_git_ancestor(fname) or vim.loop.os_homedir()
     end;
   };
   docs = {
@@ -17,7 +26,7 @@ https://github.com/leanprover/lean-client-js/tree/master/lean-language-server
 Lean language server.
     ]];
     default_config = {
-      root_dir = [[root_pattern(".git") or os_homedir]];
+      root_dir = [[find_toml() or root_pattern(".git") or os_homedir]];
     };
   };
 }