Pueden leer la versión en español aquí.
After a long time in development neovim 0.5 was finally released as a stable version. Among the new exciting features we have better lua support and the promise of a stable api to create our configuration using this language. So today I’m going to share with you everything I learnt while I was migrating my own configuration from vimscript to lua.
I’m going to talk about the things we can do with lua and its interaction with vimscript. I will be showing a lot of examples but I will not tell you what options you should set with what value. Also, this won’t be a tutorial on “how to turn neovim into an IDE”, I’ll avoid anything that is language specific. What I want to do is teach you enough about lua and the neovim api so you can migrate your own configuration.
I will assume your operating system is linux (or something close to it) and that your configuration is located at ~/.config/nvim/init.vim
. Everything that I will show should work on every system in which neovim can be installed, just keep in mind that the path to the init.vim
file might be different in your case.
Let us begin.
First steps
The first thing you need to know is that we can embed lua code directly in init.vim
. So we can migrate our config piece by piece and only change from init.vim
to init.lua
when we are ready.
Let’s do the “hello world” to test that everything works as expected. Try this in your init.vim
.
lua <<EOF
print('hello from lua')
EOF
After “sourcing” the file or restarting neovim the message hello from lua
should appear right below your statusline. In here we are using something called lua-heredoc
, so everything that’s between <<EOF ... EOF
will be considered a lua script and will be executed by the lua
command. This is useful when we want to execute multiple lines of code but it’s not necessary when we only need one. This is valid.
lua print('this also works')
But if we are going to call lua code from vimscript I say we use a real script. In lua we can do this by using the require
function. For this to work we need to create a lua
folder somewhere in the runtimepath
of neovim.
You’ll probably want to use the same folder where init.vim
is located, so we will create ~/.config/nvim/lua
, and inside that we’ll create a script called basic.lua
. For now we will only print a message.
print('hello from ~/config/nvim/lua/basic.lua')
Now from our init.vim
we can call it like this.
lua require('basic')
When we do this neovim will search in every directory in the runtimepath
for a folder called lua
and inside that it’ll look for basic.lua
. Neovim will run the last script that meets those conditions.
If you go around and check other people’s code you’ll notice that they use a .
as a path separator. For example, let’s say they have the file ~/.config/nvim/lua/usermod/settings.lua
. If they want to call settings.lua
they do this.
require('usermod.settings')
Is a very common convention. Just remember that the dot is a path separator.
With all this knowledge we are ready to begin our configuration using lua.
Editor settings
Each option in neovim is available to us in the global variable called vim
… well more than just a variable try think of this as a global module. With vim
we have access to the editor’s settings, we also have the neovim api and even a set of helper functions (a standard library if you will). For now, we only need to care about something they call “meta-accessors”, is what we’ll use to access all the options we need.
Scopes
Just like in vimscript, in lua we have different scopes for each option. We have global settings, window settings, buffer settings and a few others. Each one has its own namespace inside the vim
module.
- vim.o
Gets or sets general settings.
vim.o.background = 'light'
- vim.wo
Gets or sets window-scoped options.
vim.wo.colorcolumn = '80'
- vim.bo
Gets or sets buffer-scoped options.
vim.bo.filetype = 'lua'
- vim.g
Gets or sets global variables. This is usually the namespace where you’ll find variables set by plugins. The only one I know isn’t tied to a plugin is the leader key.
-- use space as a the leader key
vim.g.mapleader = ' '
You should know that some variable names in vimscript are not valid in lua. We still have access to them but we can’t use the dot notation. For example, vim-zoom has a variable called zoom#statustext
and in vimscript we use it like this.
let g:zoom#statustext = 'Z'
In lua we would have to do this.
vim.g['zoom#statustext'] = 'Z'
As you might have guessed this also gives us an oportunity to access properties which have the name of keywords. You may find yourselves in a situation where you need to access a property called for
, do
or end
which a are reserved keywords, in those cases remember this bracket syntax.
- vim.env
Gets or sets environment variables.
vim.env.FZF_DEFAULT_OPTS = '--layout=reverse'
As far as I know if you make a change in an environment variables the change will only apply in the active neovim session.
But now how do we know which “scope” we need to use when we’re writting our config? Don’t worry about that, think of vim.o
and company just as a way to read values. When it’s time set values we can use another method.
vim.opt
With vim.opt
we can set global, window and buffer settings.
-- buffer-scoped
vim.opt.autoindent = true
-- window-scoped
vim.opt.cursorline = true
-- global scope
vim.opt.autowrite = true
When we use it like this vim.opt
acts like the :set
command in vimscript, it give us a consistent way to modify neovim’s options.
A funny thing you can do is assign vim.opt
to a variable called set
.
Say we have this piece of vimscript.
" Set the behavior of tab
set tabstop=2
set shiftwidth=2
set softtabstop=2
set expandtab
We could translate this easily in lua like this.
local set = vim.opt
-- Set the behavior of tab
set.tabstop = 2
set.shiftwidth = 2
set.softtabstop = 2
set.expandtab = true
When you declare a variable do not forget the
local
keyword. In lua variables are global by default (that includes functions).
Anyway, what about global variables or the environment variables? For those you should keep using vim.g
and vim.env
respectively
What’s interesting about vim.opt
is that each property is a kind of special object, they are “meta-tables”. It means that these objects implement their own behavior for certain common operations.
In the first example we had something like this: vim.opt.autoindent = true
, and now you might think you can inspect the current value by doing this.
print(vim.opt.autoindent)
You won’t get the value you expect, print
will tell you vim.opt.autoindent
is a table. If you want to know the value of an option you’ll need to use the :get()
method.
print(vim.opt.autoindent:get())
If you really, really want to know what’s inside vim.out.autoindent
you need to use vim.inspect
.
print(vim.inspect(vim.opt.autoindent))
Now that will show you the internal state of this property.
Types of data
Even when we assign a value inside vim.opt
there is a little bit of magic going on in the background. I think is important to know how vim.opt
can handle different types of data and compare it with vimscript.
- Booleans
These might not seem like a big deal but there is still a difference that is worth mention.
In vimscript we can activate or deactivate an option like this.
set cursorline
set nocursorline
This is the equivalent in lua.
vim.opt.cursorline = true
vim.opt.cursorline = false
- Lists
For some options neovim expects a comma separated list. In this case we could provide it as a string ourselves.
vim.opt.wildignore = '*/cache/*,*/tmp/*'
Or we could use a table.
vim.opt.wildignore = {'*/cache/*', '*/tmp/*'}
If you check the content of vim.o.wildignore
you’ll notice is the thing we want */cache/*,*/tmp/*
. If you really want to be sure you can check with this command.
:set wildignore?
You’ll get the same result.
But the magic does not end there. Sometimes we don’t need to override the list, sometimes we need to add an item or maybe delete it. To makes things easier vim.opt
offers support for the following operations:
Add an item to the end of the list
Let’s take errorformat
as an example. If we want to add to this list using vimscript we do this.
set errorformat+=%f\|%l\ col\ %c\|%m
In lua we have a couple of ways to achieve the same goal:
Using the +
operator.
vim.opt.errorformat = vim.opt.errorformat + '%f|%l col %c|%m'
Or the :append
method.
vim.opt.errorformat:append('%f|%l col %c|%m')
Add to the beginning
In vimscript:
set errorformat^=%f\|%l\ col\ %c\|%m
Lua:
vim.opt.errorformat = vim.opt.errorformat ^ '%f|%l col %c|%m'
-- or try the equivalent
vim.opt.errorformat:prepend('%f|%l col %c|%m')
Delete an item
Vimscript:
set errorformat-=%f\|%l\ col\ %c\|%m
Lua:
vim.opt.errorformat = vim.opt.errorformat - '%f|%l col %c|%m'
-- or the equivalent
vim.opt.errorformat:remove('%f|%l col %c|%m')
- Pairs
Some options expect a list of key-value pairs. To ilustrate this we’ll use listchars
.
set listchars=tab:▸\ ,eol:↲,trail:·
In lua we can use tables for this too.
vim.opt.listchars = {eol = '↲', tab = '▸ ', trail = '·'}
Note: to actually see this on your screen you need to enable the
list
option. See :help listchars.
Since we are still using tables this option also supports the same operations mentioned in the previous section.
Calling vim functions
Vimscript like any other programming language it has its own built-in functions (many functions) and thanks to the vim
module we can call them throught vim.fn
. Just like vim.opt
, vim.fn
is a meta-table, but this one is meant to provide a convenient syntax for us to call vim functions. We use it to call built-in functions, user defined functions and even functions of plugins that are not written in lua.
We could for example check the neovim version like this:
if vim.fn.has('nvim-0.5') == 1 then
print('we got neovim 0.5')
end
Wait, hold up, why are we comparing the result of has
with a 1
? Ah, well, it turns out vimscript only included booleans in the 7.4.1154
version. So functions like has
return 0
or 1
, and in lua both are truthy.
I’ve already mentioned that vimscript can have variable names that are valid in lua, in that case you know you can use square brackets like this.
vim.fn['fzf#vim#files']('~/projects', false)
But what you need to know now is that we can also use vim.call
.
vim.call('fzf#vim#files', '~/projects', false)
Those two do the exact same thing. In practice vim.fn.somefunction()
and vim.call('somefunction')
have the same effect. They are the same.
Now let me show you something cool. In this particular case the lua-vimscript integration is so good we can use a plugin manager without any special adapters.
vim-plug in lua
I know there is a lot of people out there who use vim-plug, you might think you need to migrate to a plugin manager that is written in lua, but that’s not the case. We can use vim.fn
and vim.call
to bring vim-plug to lua.
local Plug = vim.fn['plug#']
vim.call('plug#begin', '~/.config/nvim/plugged')
-- List of plugins goes here
-- ....
vim.call('plug#end')
Those 3 lines of code are the only thing you need. You can try it, this works.
local Plug = vim.fn['plug#']
vim.call('plug#begin', '~/.config/nvim/plugged')
Plug 'wellle/targets.vim'
Plug 'tpope/vim-surround'
Plug 'tpope/vim-repeat'
vim.call('plug#end')
Before you say anything, yes, all of that is valid lua. If a function only recieves a single argument, and that argument is a string or a table, you can omit the parenthesis.
If you use the second argument of Plug
you’ll need the parenthesis and the second argument must be a table. Let me show you. If you have this in vimscript.
Plug 'scrooloose/nerdtree', {'on': 'NERDTreeToggle'}
In lua you’ll need to do this.
Plug('scrooloose/nerdtree', {on = 'NERDTreeToggle'})
Unfortunately vim-plug
has a couple of options that will cause an error if we use this syntax, those are for
and do
. In this case we need to wrap the key in quotes and square brackets.
Plug('junegunn/goyo.vim', {['for'] = 'markdown'})
You might know that the do
option takes a string or a function which will be executed when the plugin is updated or installed. But what you might not know is that we are not forced to use a “vim function”, we can use lua function and it’ll work just fine.
Plug('VonHeikemen/rubber-themes.vim', {
['do'] = function()
vim.opt.termguicolors = true
vim.cmd('colorscheme rubber')
end
})
There you have it. You don’t need to use a plugin manager written in lua if you don’t want to.
Vimscript is still our friend
You might have notice in that last example I used vim.cmd
to set the color scheme, this is because there are still things we can’t do with lua. Right now we can’t create or call ex-commands, same goes for autocommands.
To overcome these limitations we usually use vim.cmd
. This function can execute multiple lines of vimscript. It means that we can do lots of things in a single call.
vim.cmd [[
syntax enable
colorscheme rubber
command! Hello echom "hello!!"
]]
So anything that you can’t “translate” to lua you can put it in a string and pass that to vim.cmd
.
I told you we can execute any vim command, right? I feel compelled to tell you this includes the source
command. For those who don’t know, source
allows us to call other files written in vimscript. For example, in my config I use this to make some tweaks to the colorscheme. I do this.
vim.cmd 'source ~/.config/nvim/theme.vim'
And theme.vim
creates an autocommand that will be triggered everytime there is a ColorScheme
event.
function! MyHighlights() abort
hi! link Question String
hi! link NonText LineNr
hi! link TelescopeMatching Boolean
hi! link TelescopeSelection CursorLine
endfunction
augroup MyColors
autocmd!
autocmd ColorScheme * call MyHighlights()
augroup END
I like to keep this snippet in a separate file because is very likely I will keep adding lines to it. Also, there is no way to this in lua yet.
Keybindings
Here we find ourselves in an interesting situation. We actually can define our keybindings in lua but we don’t have a “convenient” api just yet. Why do I say that? First thing is that the current way doesn’t feel familiar, it’s very different from vimscript. The other thing is that we can’t bind a lua function to a key. We can call a lua function from a keyboard shortcut, but we basically have to cheat (I’ll tell you how).
Anyway, these are the two functions we have available right now.
vim.api.nvim_set_keymap
vim.api.nvim_buf_set_keymap
The first one can be used to set global keybindings and the other sets keybindings only in a buffer.
nvim_set_keymap
takes 4 arguments:
- Mode. But not the name of the mode, we need the abbreviation. You can find a list of valid options here.
- Key we want to bind.
- Action we want to execute.
- Extra arguments. These are the same options we would use in vimscript (except for
buffer
), you can find the list here.
nvim_buf_set_keymap
is the same, the only difference is that the first argument should be the number of the buffer. If you use the number0
neovim will asume you want the keybinding to take effect in the current buffer.
So if we wanted to translate this to lua.
nnoremap <Leader>w :write<CR>
We would have to do this.
vim.api.nvim_set_keymap('n', '<Leader>w', ':write<CR>', {noremap = true})
Not the greatest thing in the world but there something we can do to make it a bit more convenient.
- Make an alias
If you prefer a simple approach you could assign this function to a variable with a short name.
local map = vim.api.nvim_set_keymap
map('n', '<Leader>w', ':write<CR>', {noremap = true})
- Make a helper function
If you’re willing to put more lines of code you could create another function, one that has the default values you want. I mention this because it is considered a good practice to make our keybindings non-recursive by default.
local map = function(key)
-- get the extra options
local opts = {noremap = true}
for i, v in pairs(key) do
if type(i) == 'string' then opts[i] = v end
end
-- basic support for buffer-scoped keybindings
local buffer = opts.buffer
opts.buffer = nil
if buffer then
vim.api.nvim_buf_set_keymap(0, key[1], key[2], key[3], opts)
else
vim.api.nvim_set_keymap(key[1], key[2], key[3], opts)
end
end
Basic usage.
map {'n', '<Leader>w', ':write<CR>'}
A cool thing about this function is that it takes advantage of the way we can create tables in lua. So this is valid.
map {noremap = false, 'n', '<Leader>e', '%'}
And so is this.
map {'n', '<Leader>e', '%', noremap = false}
Calling lua functions
If we apply the knowledge we gained already about calling lua from vimscript, then we can do this.
Assuming we have a lua module called usermod
and this module has a function called somefunction
.
vim.api.nvim_set_keymap(
'n',
'<Leader>w',
"<cmd>lua require('usermod').somefunction()<CR>",
{noremap = true}
)
Now, things change a little bit if we need an expression. In that case we can’t use <cmd>lua
. We would need the variable v:lua
, with this variable we can call lua functions that exists in the global scope.
To show you how this would work I’ll try to make a smart <Tab>
key. When the autocomplete menu is visible I want to navigate throught the list of results, otherwise it’ll act like a regular <Tab>
.
local t = function(str)
return vim.api.nvim_replace_termcodes(str, true, true, true)
end
_G.smart_tab = function()
if vim.fn.pumvisible() == 1 then
return t'<C-n>'
else
return t'<Tab>'
end
end
vim.api.nvim_set_keymap(
'i',
'<Tab>',
'v:lua.smart_tab()',
{noremap = true, expr = true}
)
In lua
_G
is the global table that holds all the global variables. It’s not strictly necessary but I’m using it to make it clear that I’m creating a global function on purpose.
If you’re asking why I return t'<C-n>'
, is because we don’t need the string <C-n>
we need the code that represents ctrl+n
, same thing with <Tab>
.
If this api is not good enough for you, consider not migrating your keybindings. Leave them in a script and call it from lua.
vim.cmd 'source ~/.config/nvim/keymap.vim'
For those of you who are actually trying to run away from vimscript I could recommend some plugins:
No need to download them all. Each one has a different way to create keybingings. Pick the one you like the most.
Plugin manager
Speaking of plugins. You might want a plugin manager that is written in lua, just because. It appears that right now these are your options:
A plugin manager that is simple and fast. I’m serious, this thing has less than 300 lines of code. It was created to download, update and remove plugins. That’s it. If you don’t need anything else, look no further, this is the plugin manager you want.
If you want more features packer
is the alternative. It has the basic features you would expect, it offers lazy-loading capabilities, has support for luarocks
(which is like a package manager for lua), it can handle “local plugins”. And does other things I don’t understand, but the point is that is a feature complete plugin manager.
This one is not written in lua but I want to add it because it does offer a lua api. It offers more features than paq
but not as much a packer
, so if you are looking for a middle ground between those two, this might be a good choice.
Conclusion
Recap time. We learnt how to use lua from vimscript. We now know how to use vimscript from lua. We have the tools to activate, deactivate and modify all sorts of options and variables in neovim. We got to know the methods we have available to create our keymaps, and we know their limitations. We figure out how to use plugin managers that aren’t written in lua, and saw a few alternatives that are written in lua. I say we are ready to use lua in neovim.
For those who want to see a real world usage or whatever, I’ll share a link to my current config in github: neovim.
Sources
- learn x in y minutes: where X=lua
- nvim-lua-guide
- :help lua-heredoc
- :help lua-vim-variables
- :help lua-stdlib
- :help function-list
- :help nvim_set_keymap()
- curist’s bundle.lua
Thank you for your time. If you find this article useful and want to support my efforts, buy me a coffee ☕.