Neovim News #12 - What's New In Neovim 0.7

April 2022

Original article: https://gpanders.com/blog/whats-new-in-neovim-0-7

Neovim 0.7 was just released, bringing with it lots of new features (and of course plenty of bug fixes). You can find the full release notes here, but in this post I’ll cover just a few of the new additions.

Table of Contents

Lua everywhere!

Neovim 0.5 saw the introduction of Lua as a first-class citizen in the Neovim ecosystem: Lua could now be used in the user’s init file, plugins, colorschemes, ftplugins, etc. Basically, anywhere that you could use a .vim file, you could now use .lua instead.

However, there were still some shortcomings in the Lua API at that time. Notably absent was the ability to create autocommands in Lua, as well as bind key mappings directly to Lua functions. In order to do either of these things, users needed to resort to workarounds involving a round trip through Vimscript conversion, which is a bit clunky:

-- Using a Lua function in a key mapping prior to 0.7
local function say_hello()
    print("Hello world!")
end

_G.my_say_hello = say_hello

vim.api.nvim_set_keymap("n", "<leader>H", "<Cmd>call v:lua.my_say_hello()<CR>", {noremap = true})

The situation was similar for autocommands and custom user commands.

In Neovim 0.7, it is now possible to use all of the usual configuration primitives (key mappings, autocommands, user commands, etc.) directly in Lua, with no Vimscript conversion necessary. This also makes it possible to bind key mappings and autocommands directly to local Lua functions:

-- Using a Lua function in a key mapping in 0.7
vim.api.nvim_set_keymap("n", "<leader>H", "", {
    noremap = true,
    callback = function()
        print("Hello world!")
    end,
})

-- Creating an autocommand in 0.7
vim.api.nvim_create_autocmd("BufEnter", {
    pattern = "*",
    callback = function(args)
        print("Entered buffer " .. args.buf .. "!")
    end,
    desc = "Tell me when I enter a buffer",
})

-- Creating a custom user command in 0.7
vim.api.nvim_create_user_command("SayHello", function(args)
    print("Hello " .. args.args)
end, {
    nargs = "*",
    desc = "Say hi to someone",
})

You may notice that nvim_set_keymap must set the Lua callback as a key in the final table argument, while nvim_create_user_command can pass the callback function directly as a positional parameter. This is a consequence of Neovim’s strict API contract, which mandates that after an API function makes it into a stable release, it’s signature must not change in any way. However, because nvim_create_user_command is a new API function, we are able to add a bit of convenience by making its second argument accept either a string or a function.

Neovim 0.7 also includes a Lua-only convenience function vim.keymap.set for easily creating new key mappings:

vim.keymap.set("n", "<leader>H", function() print("Hello world!") end)

vim.keymap.set differs from nvim_set_keymap in the following ways:

  • It can accept either a string or a Lua function as its 3rd argument.
  • It sets noremap by default, as this is what users want 99% of the time.

The help docs contain much more information: run :h vim.keymap.set in Neovim to learn more.

Finally, users can now use the API function nvim_set_hl to modify global highlight groups (the equivalent of using :hi), opening the door to pure-Lua colorschemes.

Distinguishing modifier keys

Being a terminal based application, Neovim has long been subject to the constraints of terminal emulators, one of which being that many keys are encoded the same and thus indistinguishable to applications running in the terminal. For example, <Tab> and <C-I> use the same representation, as do <CR> and <C-M>. This has long meant that it is not possible to separately map <C-I> and <Tab>: mapping one necessarily maps both.

This has long been a point of annoyance and there are multiple solutions in the wild to address it. Neovim uses Paul Evans’ libtermkey, which in turn makes use of Evans’ own fixterms proposal for encoding modifier keys in an unambiguous way. As long as the terminal emulator controlling Neovim sends keys encoded in this way, Neovim can correctly interpret them.

Neovim 0.7 now correctly distinguishes these modifier key combos in its own input processing, so users can now map e.g. <Tab> and <C-I> separately. In addition, Neovim sends an escape sequence on startup that signals to the controlling terminal emulator that it supports this style of key encoding. Some terminal emulators (such as iTerm2, foot, and tmux) use this sequence to programatically enable the different encoding.

A note of warning: this cuts both ways! You may find that existing mappings to <Tab> or <C-I> (or <CR>/<C-M>) no longer work. The fix is easy, however; simply modify your mapping to use the actual key you want to use.

In addition to disambiguating these modifier pairs, this also enables new key mappings that were not possible before, such as <C-;> and <C-1>.

Support for this depends largely on the terminal you are using, so this will not affect all users.

Global statusline

Neovim 0.7 introduces a new “global” statusline, which can be enabled by setting laststatus=3. Instead of having one statusline per window, the global statusline always runs the full available width of Neovim’s containing window. This makes it useful to display information that does not change per-window, such as VCS information or the current working directory. Many statusline plugins are already making use of this new feature.

filetype.lua

In Neovim 0.7 there is a new (experimental) way to do filetype detection. A quick primer on filetype detection: when you first start Neovim it sources a file called filetype.vim in the $VIMRUNTIME directory. This file creates several hundred BufRead,BufNewFile autocommands whose sole purpose is to infer the filetype of the file based on information about the file, most commonly the file’s name or extension, but sometimes also using the file’s contents.

If you profile your startup time with nvim --startuptime you will notice that filetype.vim is one of the slowest files to load. This is because it is expensive to create so many autocommands. An alternative way to do filetype detection is to instead create one single autocommand that fires for every new buffer and then tries to match the filetype through a sequential series of steps. This is what the new filetype.lua does.

In addition to using a single autocommand, filetype.lua uses a table-based lookup structure, meaning that in many cases filetype detection happens in constant time. And if your Neovim is compiled with LuaJIT (which it most likely is), you also get the benefit of just-in-time compilation for this filetype matching.

This feature is currently opt-in as it does not yet completely match all of the filetypes covered by filetype.vim, although it is very close (I have been using it exclusively for many months without any issues). There are two ways to opt-in to this feature:

  1. Use filetype.lua, but fallback to filetype.vim

    Add let g:do_filetype_lua = 1 to your init.vim file. This prevents any regressions in filetype matching and ensures that filetypes are always detected at least as well as they are with filetype.vim. However, you will pay the startup time cost of both filetype.lua and filetype.vim.

  2. Use only filetype.lua and do not load filetype.vim at all

    Add both let g:do_filetype_lua = 1 and let g:did_load_filetypes = 0 to your init.vim. This will exclusively use filetype.lua for filetype matching and provides all of the performance benefits outlined above, with the (small) risk of missed filetype detection.

In addition to performance benefits, filetype.lua also makes it easy to add custom filetypes. Simply create a new file ~/.config/nvim/filetype.lua and call vim.filetype.add to create new matching rules. For example:

vim.filetype.add({
    extension = {
        foo = "fooscript",
    },
    filename = {
        ["Foofile"] = "fooscript",
    },
    pattern = {
        ["~/%.config/foo/.*"] = "fooscript",
    }
})

vim.filetype.add takes a table with 3 (optional) keys corresponding to “extension”, “filename”, and “pattern” matching. The value of each table entry can either be a string (in which case it is interpreted as the filetype) or a function. For example, you may want to override Neovim’s default behavior of always classifying .h files as C++ headers by using a heuristic that only sets the filetype to C++ if the header file includes another C++-style header (i.e. one without a trailing .h):

vim.filetype.add({
    extension = {
        h = function(path, bufnr)
            if vim.fn.search("\\C^#include <[^>.]\\+>$", "nw") ~= 0 then
                return "cpp"
            end
            return "c"
        end,
    },
})

We are bringing filetype.lua closer to full parity with filetype.vim every day. The goal is to make it the default in Neovim 0.8 (with the ability to opt-out to the traditional filetype.vim).

Client-server communication

Neovim 0.7 brings some of the features of neovim-remote into the core editor. You can now use nvim --remote to open a file in an already running instance of Neovim. An example:

# In one shell session
nvim --listen /tmp/nvim.sock

# In another shell session, opens foo.txt in the first Nvim instance
nvim --server /tmp/nvim.sock --remote foo.txt

One use case for the new remote functionality is the ability to open files from the embedded terminal emulator in the primary Neovim instance, rather than creating an embedded Neovim instance running inside Neovim itself.

Looking ahead to 0.8

Neovim is a loosely structured project of motivated individuals who do the work for fun; thus, any roadmap is always a bit of a guessing game. However, there are some things already brewing that you might see in Neovim 0.8:

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