refactor!: rename vim.pretty_print => vim.print

Problem:
The function name `vim.pretty_print`:
1. is verbose, which partially defeats its purpose as sugar
2. does not draw from existing precedent or any sort of convention
   (except external projects like penlight or python?), which reduces
   discoverability, and degrades signaling about best practices.

Solution:
- Rename to `vim.print`.
- Change the behavior so that
  1. strings are printed without quotes
  2. each arg is printed on its own line
  3. tables are indented with 2 instead of 4 spaces
- Example:
  :lua ='a', 'b', 42, {a=3}
  a
  b
  42
  {
    a = 3
  }

Comparison of alternatives:
- `vim.print`:
  - pro: consistent with Lua's `print()`
  - pro: aligns with potential `nvim_print` API function which will
    replace nvim_echo, nvim_notify, etc.
  - con: behaves differently than Lua's `print()`, slightly misleading?
- `vim.echo`:
  - pro: `:echo` has similar "pretty print" behavior.
  - con: inconsistent with Lua idioms.
- `vim.p`:
  - pro: very short, fits with `vim.o`, etc.
  - con: not as discoverable as "echo"
  - con: less opportunity for `local p = vim.p` because of potential shadowing.

11 files changed, 102 insertions, 57 deletions

diff --git a/runtime/doc/deprecated.txt b/runtime/doc/deprecated.txt
index 3d861b07b3..5c8d7f044f 100644
--- a/runtime/doc/deprecated.txt
+++ b/runtime/doc/deprecated.txt
@@ -129,6 +129,7 @@ TREESITTER FUNCTIONS
 
 LUA
 - *vim.register_keystroke_callback()*	Use |vim.on_key()| instead.
+- *vim.pretty_print()*			Use |vim.print()| instead.
 
 NORMAL COMMANDS
 - *]f* *[f*		Same as "gf".
diff --git a/runtime/doc/diagnostic.txt b/runtime/doc/diagnostic.txt
index cff73ad097..f888bb0991 100644
--- a/runtime/doc/diagnostic.txt
+++ b/runtime/doc/diagnostic.txt
@@ -325,7 +325,7 @@ Example: >lua
     vim.api.nvim_create_autocmd('DiagnosticChanged', {
       callback = function(args)
         local diagnostics = args.data.diagnostics
-        vim.pretty_print(diagnostics)
+        vim.print(diagnostics)
       end,
     })
 <
diff --git a/runtime/doc/lua-guide.txt b/runtime/doc/lua-guide.txt
index 8ea84f8c60..5e2b753645 100644
--- a/runtime/doc/lua-guide.txt
+++ b/runtime/doc/lua-guide.txt
@@ -10,16 +10,16 @@
 ==============================================================================
 Introduction                                                         *lua-guide*
 
-This guide will go through the basics of using Lua in Neovim. It is not meant
+This guide will go through the basics of using Lua in Nvim. It is not meant
 to be a comprehensive encyclopedia of all available features, nor will it
 detail all intricacies. Think of it as a survival kit -- the bare minimum
-needed to know to comfortably get started on using Lua in Neovim.
+needed to know to comfortably get started on using Lua in Nvim.
 
 An important thing to note is that this isn't a guide to the Lua language
-itself. Rather, this is a guide on how to configure and modify Neovim through
+itself. Rather, this is a guide on how to configure and modify Nvim through
 the Lua language and the functions we provide to help with this. Take a look
 at |luaref| and |lua-concepts| if you'd like to learn more about Lua itself.
-Similarly, this guide assumes some familiarity with the basics of Neovim
+Similarly, this guide assumes some familiarity with the basics of Nvim
 (commands, options, mappings, autocommands), which are covered in the
 |user-manual|.
 
@@ -27,7 +27,7 @@ Similarly, this guide assumes some familiarity with the basics of Neovim
 Some words on the API                                            *lua-guide-api*
 
 The purpose of this guide is to introduce the different ways of interacting
-with Neovim through Lua (the "API"). This API consists of three different
+with Nvim through Lua (the "API"). This API consists of three different
 layers:
 
 1. The "Vim API" inherited from Vim: |ex-commands| and |builtin-functions| as
@@ -35,14 +35,14 @@ well as |user-function|s in Vimscript. These are accessed through |vim.cmd()|
 and |vim.fn| respectively, which are discussed under |lua-guide-vimscript|
 below.
 
-2. The "Neovim API" written in C for use in remote plugins and GUIs; see |api|.
+2. The "Nvim API" written in C for use in remote plugins and GUIs; see |api|.
 These functions are accessed through |vim.api|.
 
 3. The "Lua API" written in and specifically for Lua. These are any other
 functions accessible through `vim.*` not mentioned already; see |lua-stdlib|.
 
 This distinction is important, as API functions inherit behavior from their
-original layer: For example, Neovim API functions always need all arguments to
+original layer: For example, Nvim API functions always need all arguments to
 be specified even if Lua itself allows omitting arguments (which are then
 passed as `nil`); and Vim API functions can use 0-based indexing even if Lua
 arrays are 1-indexed by default.
@@ -58,7 +58,7 @@ convenient to use from Lua.
 ==============================================================================
 Using Lua                                                  *lua-guide-using-Lua*
 
-To run Lua code from the Neovim command line, use the |:lua| command:
+To run Lua code from the Nvim command line, use the |:lua| command:
 >vim
     :lua print("Hello!")
 <
@@ -69,10 +69,10 @@ local keyword are not accessible outside of the command. This won't work:
     :lua print(foo)
     " prints "nil" instead of "1"
 <
-You can also use `:lua=`, which is the same as `:lua vim.pretty_print(...)`,
-to conveniently check the value of a variable or a table:
+You can also use `:lua=`, which is equivalent to `:lua vim.print(...)`, to
+conveniently check the value of a variable or a table:
 >vim
-    :lua=package
+    :lua =package
 <
 To run a Lua script in an external file, you can use the |:source| command
 exactly like for a Vimscript file:
@@ -92,7 +92,7 @@ Finally, you can include Lua code in a Vimscript file by putting it inside a
 ------------------------------------------------------------------------------
 Using Lua files on startup                                    *lua-guide-config*
 
-Neovim supports using `init.vim` or `init.lua` as the configuration file, but
+Nvim supports using `init.vim` or `init.lua` as the configuration file, but
 not both at the same time. This should be placed in your |config| directory,
 which is typically `~/.config/nvim` for Linux, BSD, or macOS, and
 `~/AppData/Local/nvim/` for Windows. Note that you can use Lua in `init.vim`
@@ -279,7 +279,7 @@ Note that you cannot directly change fields of array variables. This won't
 work:
 >lua
     vim.g.some_global_variable.key2 = 400
-    vim.pretty_print(vim.g.some_global_variable)
+    vim.print(vim.g.some_global_variable)
     --> { key1 = "value", key2 = 300 }
 <
 Instead, you need to create an intermediate Lua table and change this:
@@ -287,7 +287,7 @@ Instead, you need to create an intermediate Lua table and change this:
     local temp_table = vim.g.some_global_variable
     temp_table.key2 = 400
     vim.g.some_global_variable = temp_table
-    vim.pretty_print(vim.g.some_global_variable)
+    vim.print(vim.g.some_global_variable)
     --> { key1 = "value", key2 = 400 }
 <
 To delete a variable, simply set it to `nil`:
@@ -350,7 +350,7 @@ use |vim.opt:get()|:
     --> {...} (big table)
     print(vim.opt.smarttab:get())
     --> false
-    vim.pretty_print(vim.opt.listchars:get())
+    vim.print(vim.opt.listchars:get())
     --> { space = '_', tab = '>~' }
 <
 ------------------------------------------------------------------------------
@@ -488,7 +488,7 @@ Autocommands                                            *lua-guide-autocommands*
 An |autocommand| is a Vim command or a Lua function that is automatically
 executed whenever one or more |events| are triggered, e.g., when a file is
 read or written, or when a window is created. These are accessible from Lua
-through the Neovim API.
+through the Nvim API.
 
 ------------------------------------------------------------------------------
 Creating autocommands                             *lua-guide-autocommand-create*
@@ -530,7 +530,7 @@ Examples:
     })
 <
 
-Neovim will always call a Lua function with a single table containing information
+Nvim will always call a Lua function with a single table containing information
 about the triggered autocommand. The most useful keys are
 • `match`: a string that matched the `pattern` (see |<amatch>|)
 • `buf`:   the number of the buffer the event was triggered in (see |<abuf>|)
@@ -667,9 +667,8 @@ cover only the basics of this advanced topic.
 ------------------------------------------------------------------------------
 Creating user commands                           *lua-guide-commands-create*
 
-User commands can be created through the Neovim API with
-`vim.api.`|nvim_create_user_command()|. This function takes three mandatory
-arguments:
+User commands can be created through with |nvim_create_user_command()|. This
+function takes three mandatory arguments:
 • a string that is the name of the command (which must start with an uppercase
   letter to distinguish it from builtin commands);
 • a string containing Vim commands or a Lua function that is executed when the
diff --git a/runtime/doc/lua.txt b/runtime/doc/lua.txt
index bcd68b7608..81e45ae9bb 100644
--- a/runtime/doc/lua.txt
+++ b/runtime/doc/lua.txt
@@ -1239,7 +1239,7 @@ which is accessed through |vim.opt:get()|:
             print(vim.o.wildignore)
 <
         In Lua using `vim.opt`: >lua
-            vim.pretty_print(vim.opt.wildignore:get())
+            vim.print(vim.opt.wildignore:get())
 <
 
 In any of the above examples, to replicate the behavior |:setlocal|, use
@@ -1258,7 +1258,7 @@ Option:get()
     the values as entries in the array: >lua
         vim.cmd [[set wildignore=*.pyc,*.o]]
 
-        vim.pretty_print(vim.opt.wildignore:get())
+        vim.print(vim.opt.wildignore:get())
         -- { "*.pyc", "*.o", }
 
         for _, ignore_pattern in ipairs(vim.opt.wildignore:get()) do
@@ -1271,7 +1271,7 @@ Option:get()
     the names as keys and the values as entries: >lua
         vim.cmd [[set listchars=space:_,tab:>~]]
 
-        vim.pretty_print(vim.opt.listchars:get())
+        vim.print(vim.opt.listchars:get())
         --  { space = "_", tab = ">~", }
 
         for char, representation in pairs(vim.opt.listchars:get()) do
@@ -1282,7 +1282,7 @@ Option:get()
     as keys and `true` as entries. >lua
         vim.cmd [[set formatoptions=njtcroql]]
 
-        vim.pretty_print(vim.opt.formatoptions:get())
+        vim.print(vim.opt.formatoptions:get())
         -- { n = true, j = true, c = true, ... }
 
         local format_opts = vim.opt.formatoptions:get()
@@ -1496,10 +1496,11 @@ paste({lines}, {phase})                                          *vim.paste()*
     See also: ~
         |paste| @alias paste_phase -1 | 1 | 2 | 3
 
-pretty_print({...})                                       *vim.pretty_print()*
-    Prints given arguments in human-readable format. Example: >lua
-      -- 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))
+print({...})                                                     *vim.print()*
+    "Pretty prints" the given arguments and returns them unmodified.
+
+    Example: >lua
+      local hl_normal = vim.print(vim.api.nvim_get_hl_by_name('Normal', true))
 <
 
     Return: ~
diff --git a/runtime/doc/news.txt b/runtime/doc/news.txt
index 48d954fe2d..66e8e5ef9f 100644
--- a/runtime/doc/news.txt
+++ b/runtime/doc/news.txt
@@ -55,6 +55,8 @@ The following changes may require adaptations in user config or plugins.
   - The `concat` option has been removed as it was not consistently applied.
   - Invalid ranges now cause an error instead of returning `nil`.
 
+• Renamed vim.pretty_print to vim.print. |deprecated|
+
 ==============================================================================
 NEW FEATURES                                                    *news-features*
 
diff --git a/runtime/lua/vim/_editor.lua b/runtime/lua/vim/_editor.lua
index 9516233b45..5445c4e492 100644
--- a/runtime/lua/vim/_editor.lua
+++ b/runtime/lua/vim/_editor.lua
@@ -778,22 +778,37 @@ do
   end
 end
 
----Prints given arguments in human-readable format.
----Example:
----<pre>lua
----  -- 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 any # given arguments.
+---@private
 function vim.pretty_print(...)
-  local objects = {}
+  vim.deprecate('vim.pretty_print', 'vim.print', '0.10')
+  return vim.print(...)
+end
+
+--- "Pretty prints" the given arguments and returns them unmodified.
+---
+--- Example:
+--- <pre>lua
+---   local hl_normal = vim.print(vim.api.nvim_get_hl_by_name('Normal', true))
+--- </pre>
+---
+--- @see |vim.inspect()|
+--- @return any # given arguments.
+function vim.print(...)
+  if vim.in_fast_event() then
+    print(...)
+    return ...
+  end
+
   for i = 1, select('#', ...) do
-    local v = select(i, ...)
-    table.insert(objects, vim.inspect(v))
+    local o = select(i, ...)
+    if type(o) == 'string' then
+      vim.api.nvim_out_write(o)
+    else
+      vim.api.nvim_out_write(vim.inspect(o, { newline = '\n', indent = '  ' }))
+    end
+    vim.api.nvim_out_write('\n')
   end
 
-  print(table.concat(objects, '    '))
   return ...
 end
 
diff --git a/runtime/plugin/nvim.lua b/runtime/plugin/nvim.lua
index 762e9519db..e4b099f7ad 100644
--- a/runtime/plugin/nvim.lua
+++ b/runtime/plugin/nvim.lua
@@ -1,6 +1,6 @@
 vim.api.nvim_create_user_command('Inspect', function(cmd)
   if cmd.bang then
-    vim.pretty_print(vim.inspect_pos())
+    vim.print(vim.inspect_pos())
   else
     vim.show_pos()
   end
diff --git a/src/nvim/lua/executor.c b/src/nvim/lua/executor.c
index 11a02ea402..819e3cccff 100644
--- a/src/nvim/lua/executor.c
+++ b/src/nvim/lua/executor.c
@@ -1623,12 +1623,12 @@ void ex_lua(exarg_T *const eap)
   }
   // When =expr is used transform it to print(vim.inspect(expr))
   if (code[0] == '=') {
-    len += sizeof("vim.pretty_print()") - sizeof("=");
+    len += sizeof("vim.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);
+    vim_snprintf(code_buf, len + 1, "vim.print(%s)", code + 1);
     xfree(code);
     code = code_buf;
   }
diff --git a/test/functional/api/vim_spec.lua b/test/functional/api/vim_spec.lua
index 48ac491ade..2af041c706 100644
--- a/test/functional/api/vim_spec.lua
+++ b/test/functional/api/vim_spec.lua
@@ -4042,7 +4042,7 @@ describe('API', function()
     it('splits arguments correctly for Lua callback', function()
       meths.exec_lua([[
         local function FooFunc(opts)
-          vim.pretty_print(opts.fargs)
+          vim.print(opts.fargs)
         end
 
         vim.api.nvim_create_user_command("Foo", FooFunc, { nargs = '+' })
diff --git a/test/functional/lua/commands_spec.lua b/test/functional/lua/commands_spec.lua
index b8346df290..943095c51e 100644
--- a/test/functional/lua/commands_spec.lua
+++ b/test/functional/lua/commands_spec.lua
@@ -8,6 +8,8 @@ local eval = helpers.eval
 local feed = helpers.feed
 local clear = helpers.clear
 local meths = helpers.meths
+local exec_lua = helpers.exec_lua
+local exec_capture = helpers.exec_capture
 local funcs = helpers.funcs
 local source = helpers.source
 local dedent = helpers.dedent
@@ -15,7 +17,6 @@ local command = helpers.command
 local exc_exec = helpers.exc_exec
 local pcall_err = helpers.pcall_err
 local write_file = helpers.write_file
-local exec_capture = helpers.exec_capture
 local curbufmeths = helpers.curbufmeths
 local remove_trace = helpers.remove_trace
 
@@ -142,22 +143,29 @@ describe(':lua command', function()
     ]]}
   end)
 
-  it('Can print results of =expr', function()
-    helpers.exec_lua("x = 5")
-    eq("5", helpers.exec_capture(':lua =x'))
-    helpers.exec_lua("function x() return 'hello' end")
-    eq([["hello"]], helpers.exec_capture(':lua = x()'))
-    helpers.exec_lua("x = {a = 1, b = 2}")
-    eq("{\n  a = 1,\n  b = 2\n}", helpers.exec_capture(':lua  =x'))
-    helpers.exec_lua([[function x(success)
+  it('prints result of =expr', function()
+    exec_lua("x = 5")
+    eq("5", exec_capture(':lua =x'))
+    exec_lua("function x() return 'hello' end")
+    eq('hello', exec_capture(':lua = x()'))
+    exec_lua("x = {a = 1, b = 2}")
+    eq("{\n  a = 1,\n  b = 2\n}", exec_capture(':lua  =x'))
+    exec_lua([[function x(success)
       if success then
         return true, "Return value"
       else
         return false, nil, "Error message"
       end
     end]])
-    eq([[true    "Return value"]], helpers.exec_capture(':lua  =x(true)'))
-    eq([[false    nil    "Error message"]], helpers.exec_capture(':lua  =x(false)'))
+    eq(dedent[[
+      true
+      Return value]],
+    exec_capture(':lua  =x(true)'))
+    eq(dedent[[
+      false
+      nil
+      Error message]],
+    exec_capture(':lua  =x(false)'))
   end)
 end)
 
diff --git a/test/functional/lua/vim_spec.lua b/test/functional/lua/vim_spec.lua
index 77628487ca..470102df5e 100644
--- a/test/functional/lua/vim_spec.lua
+++ b/test/functional/lua/vim_spec.lua
@@ -6,6 +6,7 @@ local nvim_prog = helpers.nvim_prog
 local funcs = helpers.funcs
 local meths = helpers.meths
 local command = helpers.command
+local dedent = helpers.dedent
 local insert = helpers.insert
 local clear = helpers.clear
 local eq = helpers.eq
@@ -2269,7 +2270,7 @@ describe('lua stdlib', function()
 
   describe('vim.region', function()
     it('charwise', function()
-      insert(helpers.dedent( [[
+      insert(dedent( [[
       text tααt tααt text
       text tαxt txtα tex
       text tαxt tαxt
@@ -2923,6 +2924,24 @@ describe('lua stdlib', function()
       {4:-- Omni completion (^O^N^P) }{5:match 1 of 2}                    |
     ]]}
   end)
+
+  it('vim.print', function()
+    -- vim.print() returns its args.
+    eq({42, 'abc', { a = { b = 77 }}},
+      exec_lua[[return {vim.print(42, 'abc', { a = { b = 77 }})}]])
+
+    -- vim.print() pretty-prints the args.
+    eq(dedent[[
+
+      42
+      abc
+      {
+        a = {
+          b = 77
+        }
+      }]],
+      eval[[execute('lua vim.print(42, "abc", { a = { b = 77 }})')]])
+  end)
 end)
 
 describe('lua: builtin modules', function()