The leader key

One particular problem with remaps is that it’s quite easy to accidentally shadow existing Vim behavior. For example, nothing is stopping you from creating a normal mode mapping for the i key. This would be super annoying, though, because we would have overloaded some built-in Vim functionality with our own stuff.

The problem is worse for plugin authors, because nobody wants to ship a plugin that overrides built-in Vim functionality that users might depend on heavily.

To answer this problem, the leader key exists. The leader key works as a namespace for your mappings, or for mappings provided by plugins. The idea is that you pick a leader key — say space — and start all of your custom mappings with your chosen leader. With a well-chosen leader key, you won’t be overriding any of Vim’s built-in maps, and you’ll have a safe space to build your own functionality.

The default leader key in Vim is \ — but you can customize this by setting the mapleader variable. I use the space bar as my leader key, because it’s super easy to type. So, my mapleader variable is set like this:

let mapleader = " "

Let’s try setting the mapleader variable and creating a leader map. Work through the checklist below: set the leader to space, define the <leader>h mapping from the demo, then trigger it. (Outside this course, the mapping behind your leader can be anything you like — we prescribe this one so the editor can tell when it fires.)