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See also:
• |builtin-functions|: alphabetic list of all Vimscript functions
• |function-list|:     list of all Vimscript functions grouped by topic
• |:runtime|:          run all Lua scripts matching a pattern in |'runtimepath'|
• |package.path|:      list of all paths searched by `require()`

==============================================================================
Variables                                                  *lua-guide-variables*

Variables can be set and read using the following wrappers, which directly
correspond to their |variable-scope|:

• |vim.g|:   global variables (|g:|)
• |vim.b|:   variables for the current buffer (|b:|)
• |vim.w|:   variables for the current window (|w:|)
• |vim.t|:   variables for the current tabpage (|t:|)
• |vim.v|:   predefined Vim variables (|v:|)
• |vim.env|: environment variables defined in the editor session

Data types are converted automatically. For example:
>lua
    vim.g.some_global_variable = {
      key1 = "value",
      key2 = 300
    }

    vim.print(vim.g.some_global_variable)
    --> { key1 = "value", key2 = 300 }
<
You can target specific buffers (via number), windows (via |window-ID|), or
tabpages by indexing the wrappers:
>lua
    vim.b[2].myvar = 1               -- set myvar for buffer number 2
    vim.w[1005].myothervar = true    -- set myothervar for window ID 1005
<
Some variable names may contain characters that cannot be used for identifiers
in Lua. You can still manipulate these variables by using the syntax
>lua
    vim.g['my#variable'] = 1
<
Note that you cannot directly change fields of array variables. This won't
work:
>lua
    vim.g.some_global_variable.key2 = 400
    vim.print(vim.g.some_global_variable)
    --> { key1 = "value", key2 = 300 }
<
Instead, you need to create an intermediate Lua table and change this:
>lua
    local temp_table = vim.g.some_global_variable
    temp_table.key2 = 400
    vim.g.some_global_variable = temp_table
    vim.print(vim.g.some_global_variable)
    --> { key1 = "value", key2 = 400 }
<
To delete a variable, simply set it to `nil`:
>lua
    vim.g.myvar = nil
<
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See also:
• |lua-vim-variables|

==============================================================================
Options                                                      *lua-guide-options*

There are two complementary ways of setting |options| via Lua.

------------------------------------------------------------------------------
vim.opt

The most convenient way for setting global and local options, e.g., in `init.lua`,
is through `vim.opt` and friends:

• |vim.opt|:        behaves like |:set|
• |vim.opt_global|: behaves like |:setglobal|
• |vim.opt_local|:  behaves like |:setlocal|

For example, the Vimscript commands
>vim
    set smarttab
    set nosmarttab
<
are equivalent to
>lua
    vim.opt.smarttab = true
    vim.opt.smarttab = false
<
In particular, they allow an easy way to working with list-like, map-like, and
set-like options through Lua tables: Instead of
>vim
    set wildignore=*.o,*.a,__pycache__
    set listchars=space:_,tab:>~
    set formatoptions=njt
<
you can use
>lua
    vim.opt.wildignore = { '*.o', '*.a', '__pycache__' }
    vim.opt.listchars = { space = '_', tab = '>~' }
    vim.opt.formatoptions = { n = true, j = true, t = true }
<
These wrappers also come with methods that work similarly to their |:set+=|,
|:set^=| and |:set-=| counterparts in Vimscript:
>lua
    vim.opt.shortmess:append({ I = true })
    vim.opt.wildignore:prepend('*.o')
    vim.opt.whichwrap:remove({ 'b', 's' })
<
The price to pay is that you cannot access the option values directly but must
use |vim.opt:get()|:
>lua
    print(vim.opt.smarttab)
    --> {...} (big table)
    print(vim.opt.smarttab:get())
    --> false
    vim.print(vim.opt.listchars:get())
    --> { space = '_', tab = '>~' }
<
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