4 files changed, 84 insertions, 11 deletions
diff --git a/src/nvim/lua/converter.c b/src/nvim/lua/converter.c
index b6792a5a97..8a702ddd60 100644
--- a/src/nvim/lua/converter.c
+++ b/src/nvim/lua/converter.c
@@ -1242,7 +1242,12 @@ LuaRef nlua_pop_LuaRef(lua_State *const lstate, Error *err)
   FUNC_ATTR_NONNULL_ALL FUNC_ATTR_WARN_UNUSED_RESULT \
   { \
     type ret; \
-    ret = (type)lua_tonumber(lstate, -1); \
+    if (lua_type(lstate, -1) != LUA_TNUMBER) { \
+      api_set_error(err, kErrorTypeValidation, "Expected Lua number"); \
+      ret = (type)-1; \
+    } else { \
+      ret = (type)lua_tonumber(lstate, -1); \
+    } \
     lua_pop(lstate, 1); \
     return ret; \
   }
diff --git a/src/nvim/lua/executor.c b/src/nvim/lua/executor.c
index 7d43d21d53..cfdbe7b344 100644
--- a/src/nvim/lua/executor.c
+++ b/src/nvim/lua/executor.c
@@ -434,6 +434,15 @@ static int nlua_state_init(lua_State *const lstate) FUNC_ATTR_NONNULL_ALL
     // [package, loaded, module]
     lua_setfield(lstate, -2, "vim.F");  // [package, loaded]
 
+    code = (char *)&lua_filetype_module[0];
+    if (luaL_loadbuffer(lstate, code, sizeof(lua_filetype_module) - 1, "@vim/filetype.lua")
+        || nlua_pcall(lstate, 0, 1)) {
+      nlua_error(lstate, _("E5106: Error while creating vim.filetype module: %.*s"));
+      return 1;
+    }
+    // [package, loaded, module]
+    lua_setfield(lstate, -2, "vim.filetype");  // [package, loaded]
+
     lua_pop(lstate, 2);  // []
   }
 
@@ -1115,11 +1124,23 @@ void ex_lua(exarg_T *const eap)
   FUNC_ATTR_NONNULL_ALL
 {
   size_t len;
-  char *const code = script_get(eap, &len);
+  char *code = script_get(eap, &len);
   if (eap->skip) {
     xfree(code);
     return;
   }
+  // When =expr is used transform it to print(vim.inspect(expr))
+  if (code[0] == '=') {
+    len += sizeof("vim.pretty_print()") - sizeof("=");
+    // code_buf needs to be 1 char larger then len for null byte in the end.
+    // lua nlua_typval_exec doesn't expect null terminated string so len
+    // needs to end before null byte.
+    char *code_buf = xmallocz(len);
+    vim_snprintf(code_buf, len+1, "vim.pretty_print(%s)", code+1);
+    xfree(code);
+    code = code_buf;
+  }
+
   nlua_typval_exec(code, len, ":lua", NULL, 0, false, NULL);
 
   xfree(code);
diff --git a/src/nvim/lua/spell.c b/src/nvim/lua/spell.c
index b84124bc19..3a63f61200 100644
--- a/src/nvim/lua/spell.c
+++ b/src/nvim/lua/spell.c
@@ -1,3 +1,5 @@
+// This is an open source non-commercial project. Dear PVS-Studio, please check
+// it. PVS-Studio Static Code Analyzer for C, C++ and C#: http://www.viva64.com
 
 #include <lua.h>
 #include <lauxlib.h>
diff --git a/src/nvim/lua/vim.lua b/src/nvim/lua/vim.lua
index f9b15d242a..731e7d8d36 100644
--- a/src/nvim/lua/vim.lua
+++ b/src/nvim/lua/vim.lua
@@ -40,6 +40,9 @@ assert(vim)
 vim.inspect = package.loaded['vim.inspect']
 assert(vim.inspect)
 
+vim.filetype = package.loaded['vim.filetype']
+assert(vim.filetype)
+
 local pathtrails = {}
 vim._so_trails = {}
 for s in  (package.cpath..';'):gmatch('[^;]*;') do
@@ -112,6 +115,9 @@ setmetatable(vim, {
     elseif key == 'ui' then
       t.ui = require('vim.ui')
       return t.ui
+    elseif key == 'keymap' then
+      t.keymap = require('vim.keymap')
+      return t.keymap
     end
   end
 })
@@ -419,23 +425,43 @@ function vim.defer_fn(fn, timeout)
 end
 
 
---- Notification provider
+--- Display a notification to the user.
+---
+--- This function can be overridden by plugins to display notifications using a
+--- custom provider (such as the system notification provider). By default,
+--- writes to |:messages|.
 ---
---- Without a runtime, writes to :Messages
----@see :help nvim_notify
----@param msg string Content of the notification to show to the user
----@param log_level number|nil enum from |vim.log.levels|
----@param opts table|nil additional options (timeout, etc)
-function vim.notify(msg, log_level, opts) -- luacheck: no unused
-  if log_level == vim.log.levels.ERROR then
+---@param msg string Content of the notification to show to the user.
+---@param level number|nil One of the values from |vim.log.levels|.
+---@param opts table|nil Optional parameters. Unused by default.
+function vim.notify(msg, level, opts) -- luacheck: no unused args
+  if level == vim.log.levels.ERROR then
     vim.api.nvim_err_writeln(msg)
-  elseif log_level == vim.log.levels.WARN then
+  elseif level == vim.log.levels.WARN then
     vim.api.nvim_echo({{msg, 'WarningMsg'}}, true, {})
   else
     vim.api.nvim_echo({{msg}}, true, {})
   end
 end
 
+do
+  local notified = {}
+
+  --- Display a notification only one time.
+  ---
+  --- Like |vim.notify()|, but subsequent calls with the same message will not
+  --- display a notification.
+  ---
+  ---@param msg string Content of the notification to show to the user.
+  ---@param level number|nil One of the values from |vim.log.levels|.
+  ---@param opts table|nil Optional parameters. Unused by default.
+  function vim.notify_once(msg, level, opts) -- luacheck: no unused args
+    if not notified[msg] then
+      vim.notify(msg, level, opts)
+      notified[msg] = true
+    end
+  end
+end
 
 ---@private
 function vim.register_keystroke_callback()
@@ -663,4 +689,23 @@ vim._expand_pat_get_parts = function(lua_string)
   return parts, search_index
 end
 
+---Prints given arguments in human-readable format.
+---Example:
+---<pre>
+---  -- Print highlight group Normal and store it's contents in a variable.
+---  local hl_normal = vim.pretty_print(vim.api.nvim_get_hl_by_name("Normal", true))
+---</pre>
+---@see |vim.inspect()|
+---@return given arguments.
+function vim.pretty_print(...)
+  local objects = {}
+  for i = 1, select('#', ...) do
+    local v = select(i, ...)
+    table.insert(objects, vim.inspect(v))
+  end
+
+  print(table.concat(objects, '    '))
+  return ...
+end
+
 return module