vim.keymap.set issue

Question

I've tried to make a key map as follows:

vim.keymap.set('x', '<leader>n', function() -- Here <leader> is <Space>
    line1r, line1c  = unpack(vim.api.nvim_buf_get_mark(0, "<"))
    line2r, line2c = unpack(vim.api.nvim_buf_get_mark(0, ">"))
    print("line1r = " .. line1r .. "; line2r = " .. line2r)
  end, { noremap = true })

(Select some lines and print the first line number and the last line number)

When I select some lines in visual mode and type <leader>, which-key shows n indicating this map exists.

However, it does not print line 1= <some number>; line2= <some number> when I type n, and it still stays in visual mode.

I'm not sure where is the wrong point.

Is there something I missed?

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[Updated 1]

I've tried to make a whole new init.lua which only contains the following setting

vim.g.mapleader = ' ' -- Set leader as <Space>
vim.keymap.set('x', '<leader>n', function()
    line1r, _  = unpack(vim.api.nvim_buf_get_mark(0, "<"))
    line2r, __ = unpack(vim.api.nvim_buf_get_mark(0, ">"))
    print("line1r = " .. line1r .. "; line2r = " .. line2r)
  end, { noremap = true })

And it still doesn't work. That's weird.

By the way, my environment info:

- NVIM v0.9.1
  Build type: RelWithDebInfo
  LuaJIT 2.1.0-beta3
- OS: Windows 10

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[Updated 2]

Using :message, it does record the printing result(s) it should have shown when the key mapping is triggered. However, these printing result does not appear exactly when the mapping is triggered. :-(

By the way, nvim seems to record the previous position of marks '< and '> rather than the "current" position. I think this may be discussed on another new question/post.

Answer 1

You mapping look good.

But you have mapped against <leader>n which is by default: \n

Unless you have define: g:mapleader.

You can know the value of g:mapleader by running the following Neovim command:

echo "'" . g:mapleader . "'"

Some people (including myself) and some distributions (including NvChad, LunarVim, LazyVim, AstroVim) defines g:mapleader to Space

In such case <leader>n corresponds to Spacen

The result of the print call should be visible as the output of the following Neovim command

:messages

I you want to see the messages when they are triggered in Visual mode you have to increase the room for them with:

:set cmdheight=2