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Semantic highlighting for Lua in Vim
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Semantic highlighting for Lua in Vim

The Vim plug-in luainspect.vim uses the LuaInspect tool to (automatically) perform semantic highlighting of variables in Lua source code. It was inspired by lua2-mode (for Emacs) and the SciTE plug-in included with LuaInspect. In addition to the semantic highlighting the following features are currently supported:

  • Press <F2> with the text cursor on a variable and the plug-in will prompt you to rename the variable.

  • Press gd (in normal mode) with the text cursor on a variable and you'll jump to its declaration / first occurrence.

  • When you hover over a variable with the mouse cursor in graphical Vim, information about the variable is displayed in a tooltip.

  • If the text cursor is on a variable while the highlighting is refreshed then all occurrences of the variable will be marked in the style of Vim's cursorline option.

  • When luainspect reports a wrong argument count for a function call the call will be highlighted with a green underline. When you hover over the highlighted text a tooltip shows the associated warning message.

  • When a syntax error is found (during highlighting or using the rename functionality) the lines where the error is reported will be marked like a spelling error.

Screenshot of semantic highlighting


Unzip the most recent ZIP archive file inside your Vim profile directory (usually this is ~/.vim on UNIX and %USERPROFILE%\vimfiles on Windows), restart Vim and execute the command :helptags ~/.vim/doc (use :helptags ~\vimfiles\doc instead on Windows). Now try it out: Edit a Lua file and within a few seconds semantic highlighting should be enabled automatically!

Note that on Windows a command prompt window pops up whenever LuaInspect is run as an external process. If this bothers you then you can install my shell.vim plug-in which includes a DLL that works around this issue. Once you've installed both plug-ins it should work out of the box!


When you open any Lua file the semantic highlighting should be enabled automatically within a few seconds, so you don't have to configure anything if you're happy with the defaults.

The :LuaInspect command

You don't need to use this command unless you've disabled automatic highlighting using g:lua_inspect_events. When you execute this command the plug-in runs the LuaInspect tool and then highlights all variables in the current buffer using one of the following highlighting groups:

  • luaInspectGlobalDefined
  • luaInspectGlobalUndefined
  • luaInspectLocalUnused
  • luaInspectLocalMutated
  • luaInspectUpValue
  • luaInspectParam
  • luaInspectLocal
  • luaInspectFieldDefined
  • luaInspectFieldUndefined
  • luaInspectSelectedVariable
  • luaInspectWrongArgCount
  • luaInspectSyntaxError

If you don't like one or more of the default styles the Vim documentation describes how to change them. If you want to disable the semantic highlighting in a specific Vim buffer execute :LuaInspect! in that buffer. When you want to reenable the highlighting execute :LuaInspect again, but now without the bang.

The g:loaded_luainspect option

This variable isn't really an option but if you want to avoid loading the luainspect.vim plug-in you can set this variable to any value in your vimrc script:

:let g:loaded_luainspect = 1

The g:lua_inspect_events option

By default semantic highlighting is automatically enabled after a short timeout and when you save a buffer. If you want to disable automatic highlighting altogether add the following to your vimrc script:

:let g:lua_inspect_events = ''

You can also add events, for example if you also want to run :LuaInspect the moment you edit a Lua file then try this:

:let g:lua_inspect_events = 'CursorHold,CursorHoldI,BufReadPost,BufWritePost'

Note that this only works when the plug-in is loaded (or reloaded) after setting the g:lua_inspect_events option.

The g:lua_inspect_internal option

The plug-in uses the Lua interface for Vim when available so that it doesn't have to run LuaInspect as an external program (which can slow things down). If you insist on running LuaInspect as an external program you can set this variable to false (0) in your vimrc script:

:let g:lua_inspect_internal = 0


If you have questions, bug reports, suggestions, etc. the author can be contacted at The latest version is available at and If you like this plug-in please vote for it on


This software is licensed under the MIT license.
© 2010 Peter Odding <>.

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