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matthewburfield

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A failed attempt at theming Vim

April 19, 2020

sunrise Photo by Johannes Plenio on Unsplash

Disclaimer: If you came here looking for how to create a theme in Vim then you’ll be sorely disappointed. This is not a story about overcoming the odds and winning in the end. This story does not have a happy ending.

Introduction

I’ve only just recently started using Vim as my main editor, moving away from the safe and comfortable VSCode to editing exclusively in the terminal.

Obviously that means moving away from an IDE - which means you will lose some functionality from the editor, but for the most part, working from the terminal has been a pretty nice experience so far as I continue to get used to working without using the mouse.

One thing that did bother me though, is the syntax highlighting. Syntax highlighting in VSCode seems to be much more expressive, especially when looking at .jsx files.

Here’s a look at a comparison between Vim in the terminal and VSCode using the one-dark themes.

A React `.jsx` file in VSCode A React .jsx file in VSCode

And conversely, here is the equivalent in Vim

A React `.jsx` file in Vim A React .jsx file in Vim

Obviously when it comes to syntax highlighting, everything is personal preference, but with all the different themes I tried to use in Vim, I always seemed to like the equivalent in VSCode better.

Naturally this led me down the path of looking into how color themes are made in Vim and whether I could edit an existing one or create my own.

After much searching around, I stumbled across this template by Gerardo Galindez which worked pretty well, it has a nice layout and has a list of all the different syntax highlighting groups in Vim, grouped by category.

This was a good starting point. I wanted to reset all the colors in Vim to nothing so I could then start adding colors one by one and build out my theme, and this template looked like it would achieve that task.

In Vim, you can load your own color theme by adding your theme (such as the template above) to the ~/.vim/colors/ directory (If that directory doesn’t exist, you can create it). Then, in your ~/.vimrc file, add the line:

colorscheme my_theme_name

Where my_theme_name is replaced with whatever you call your theme.

The template above started me down the right track for what I wanted to accomplish in completely resetting all colors, but it wasn’t the complete picture. Because I had enabled 256 color support, the syntax groups weren’t simply being highlighted with the ctermfg, ctermbg and cterm options, but were also being highlighted with guifg, guibg and gui as well. Therefore in order to truely reset all syntax highlights, I needed to set those options to none as well.

If you want to read more about those terms, I suggest starting with Vim’s internal help. (I.e. :h guifg).

I created a new template that incorporates this and now I do have a complete reset of colors. The text is plain white, while everthing else is plain black.

Now I could slowly start adding colors to each syntax group, and slowly start to build out the theme I wanted.

This was kind of working until I realised that with only the syntax groups availabile by default in Vim, I wasn’t able to customise language specific syntax groups. I only really work with a JavaScript and React, so wanted to be able to customise .jsx files.

I started looking at the internals of syntax plugins like pangloss/vim-javascript which I think create new syntax groups using a bunch of regex expressions, and then map those new syntax groups to the regular syntax groups in Vim so syntax highlighting works out of the box with other syntax highlighting plugins.

What I tried to do was reference the internally defined syntax groups defined by pangloss/vim-javascript directly. Some of these did actually work, like the jsImport and jsExport groups. However most of them didn’t, or at least, based on the name of the group, it wasn’t immediately obvious what the syntax group should actually change. This led to a lot of setting a color, then re-sourcing the vimrc in my .jsx file, to look at anything that changed.

An excruciatingly long process

I’m sure this isn’t the most efficient way to create a theme, but by this stage I had pretty much wasted an entire weekend just to get to this point and promptly gave up 😅.

Conclusion

I did warn you that this wasn’t a story with a happy ending.

My current setup is using the gruvbox light theme and I don’t mind it. Maybe some day I’ll revisit creating a theme in Vim, but for now I have better things to do.

Happy Coding!


Hi, I'm Matthew Burfield. I like writing about cool development stuff.