How do I set up a local leader key for file-type-specific mappings that don't conflict with global mappings?

Explanation

Vim provides two separate leader keys: <Leader> (global) and <LocalLeader> (local to the current buffer). By defining maplocalleader, you get a dedicated namespace for file-type-specific key mappings — typically placed in ftplugin/ files — that won't collide with your global mapleader bindings.

How it works

• mapleader — the global leader, used in <Leader> mappings (commonly set to <Space> or \)
• maplocalleader — the local leader, used in <LocalLeader> mappings in ftplugin/ or after/ftplugin/
• <buffer> flag on a mapping — makes it active only in the current buffer (essential in ftplugins)
• The two leaders can be the same character but are logically distinct

Example

In your vimrc:

let mapleader = ' '
let maplocalleader = ','

In ~/.vim/ftplugin/python.vim:

" Run the current file with Python
nnoremap <buffer> <LocalLeader>r :!python3 %<CR>

" Insert a breakpoint
nnoremap <buffer> <LocalLeader>b Oimport pdb; pdb.set_trace()<Esc>

Now ,r runs Python files, but only inside .py buffers. The global <Space>r mapping is untouched.

Tips

• Always use <buffer> alongside <LocalLeader> in ftplugin files to prevent leaking mappings to other buffers
• Choose a maplocalleader character that differs from mapleader to keep namespaces distinct
• In Neovim Lua, use vim.keymap.set('n', '<LocalLeader>r', ..., { buffer = true }) for the same effect
• List active buffer-local mappings with :nmap <buffer>