space vim

saturday, 5 march 2016

leader keys allow chording command sequences. The two most powerful text editors (IMO), emacs and Vim, utilize chording keymaps.

Recently, I came across a reference to an active emacs configuration called Spacemacs which uses the Space key for such. I had considered using the Space key as the <leader> key early on in my configuration of Vim but ultimately chose the more commonly used comma leader key – following popular convention.

Spacemacs changed all that. As a former user of emacs before slipping to the dark side and Vi/Vim decades ago, Spacemacs emulation of Vim via Evil mode could not be resisted. Ultimately, my initial experience was insufficient to convince me to switch back, despite the allure of elisp over Vim’s native language syntax. (Had Evil mode been available back when I was a developer, undoubtedly I would have remained an emacs user.)

I don’t see myself switching off the Vim platform, especially with the distraction free plugins I use for writing and the tight integration of vimwiki with this web site. But Spacemacs did pique my interest in using the Space key as a leader key which is set with..

let mapleader = "\<Space>"

Using the thumbs is preferable over the right middle finger for the leader key which should come as no surprise for someone who has designed his own Colemak Shift-DH layout.

As well, this got me rethinking my key mappings altogether. In particular, the use of function keys.

Function keys are commonly mapped to plugin actions – an arbitrary convention in most cases. Restricting function key assignments to seldom used display configuration actions such as distraction free modes, statusline configuration, etc., left defining more easily remembered leader key mappings for plugins, using the related Vim mnemonic keys.

So, the yankring plugin is assigned to <leader>y and the undo tree plugin is assigned to <leader>u to complement Vi/Vim’s y yank and u undo actions respectively. No more need to remember arbitrary function key assignments. Where ever possible, plugins are now leader mapped to their Vim couterparts. Beautiful.

Using the Space key is not without its downsides. Some seemingly convenient insert mode mappings had to be dropped because typing Space <letter> is common. This turned out not to be as much of an inconvenience as originally thought. Even though many such imap or insert mode keybinds were defined in my previous Vim configuration, it turns out I seldom used such keybinds in practice, instead using the nmap or normal (command) mode keybind.

More noticeable, however, is the lag time introduced with the Space leader. While typing, the next word will not be space separated until the first letter of the word is struck – unless you pause long enough for the leader check to complete. It doesn’t take long to get used to this behaviour while looking at the screen but it’s there – touch typing at a moderate speed blurs this perception to be all but unnoticeable.

There are times this delay can be a nuisance, though, and that is when successive Spaces are inserted into the document or source code line to column align text, because multiple Space insertions easily get ahead of the leader checking. For that case, defining a Ctrl-Space keymap to insert Spaces ignoring the default leader processing check does the trick with no lag time penalty..

inoremap <C-Space> <Space>

Changing the Vim leader key from the comma to the Space doesn’t seem like a big deal. But for me, Vim semantically, it is. It just feels so much more correct and natural. Thankyou Spacemacs. YMMV. As per usual, my Vim configurations can be found here.

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