A Python Flakes plugin


static code analysis optimized for crappy Python ™

khuno.vim - A Python flakes Vim plugin

Analyze your code with Tarek Ziade's Flake8 in Vim - seamlessly.

There is nothing like this

  • Non-blocking (syntax check is called asynchronously)
  • statusline helper to display (or not!) when there are errors.
  • Separate buffer to display errors and jump to them (a la QuickFix)
  • highly performing, every bit of the plugin is meant to be as fast as possible.

I would still consider this an alpha version, there are some undocumented things (on purpose, I swear) that need some work, but feedback and complaints are welcomed and encouraged.

Bug me at @alfredodeza on Twitter or fill the issues tab for this project.



I started this plugin because I am (was! ha!) pissed off at the alternatives. Most solutions require a blocking call to the checker program, you can't do anything else until that call ends.

That is unacceptable. I can't work like that. This plugin will not block while you work in Vim.

A note on Pyflakes.vim: I used this until recently but the plugin is no longer maintained.


If you have Tim Pope's Pathogen.vim then you are already set, just clone this plugin into the bundle directory. If you do not use Pathogen.vim you will need to distribute the files accordingly.

After you have installed the plugin you will need 2 more things:

1. pip install flake8 This needs to be in your path, it doesn't matter where it is installed.

2. filetype plugin on Enable the filetype detection in Vim that matches the file type to plugins.


khuno.vim will not yell at you if you do not have flake8 installed. It will only issue a warning if you try to use it directly, like :Khuno run

Basic Usage

Open any Python file. As soon as you enter one, an asynchronous call will be made to flake8, saving the results.

If you move the cursor, it will then proceed to read the results from the check and underline all the words or lines in the current file.

Every time you save the file or you are exiting insert mode you will trigger the asynchronous call, enforcing a refresh of the check and error display.

Even if you have unsaved (modified buffer) changes, they will show up.


To add builtins, in your .vimrc:

let g:khuno_builtins="_,apply"

To ignore errors, in your .vimrc:

let g:khuno_ignore="E501,W293"

If you want to change the max line length for PEP8:

let g:khuno_max_line_length=99

To customize the location of your flake8 binary, set g:khuno_flake_cmd:

let g:khuno_flake_cmd="/opt/strangebin/flake8000"

Showing Errors and Jumping

Just like what you would expect from something that pushes errors to the QuickFix Window, except khuno.vim doesn't overload that. You should map the call to the command below for convenience, but either way, this is how you would trigger the window:

:Khuno show

To map it, use something like this (say, for your leader key + x):

nmap <silent><Leader>x <Esc>:Khuno show<CR>

This command is toggable, if the split window is already open, this command will close it, otherwise it will open it.

When the window is triggered, it will appear at the bottom and display 10 lines at the most (to avoid clobbering the whole space). And a list will be shown with contents similar to this:

Line: 79  Col: 80  ==> E501 line too long (80 > 79 characters)

There is a special mapping for that buffer: if you press enter it will go the previous window and move to the exact line and column where that error was triggered.

statusline helper function

If you want to display some text when there are errors in the file, you can use the helper function. I use the optional text to display all my anger when there are errors, like:

set statusline=%#ErrorMsg#                   " set the highlight to error
set statusline+=%{khuno#Status('FUU')}%*     " are there any errors? FUU!
set statusline+=%*                           " switch back to normal status color

The text is optional, it will default to [N], where N is the number of errors for the current buffer.

Disabling/Enabling the checker

You can also disable the check on a specific buffer with:

:Khuno off

To turn it on again, you can run:

:Khuno on


Nothing seems to be happenning although I know there are errors: A couple of things here: make sure you followed the installation instructions (e.g. filetype on) including having flake8 installed and available on your path. If all else fails, and Khuno loaded, run :Khuno debug that will give you debugging information that might be useful.

I opened a file (or buffer) and nothing happened: This plugin calls the checker asynchronously, so results are only fed back to the buffer when the cursor moves. If you have not moved the cursor, the plugin will not paint the buffer immediately with results.

I just type some erroneous Python but the plugin didn't show it: The plugin will be called when you enter a buffer or when you save the file, and will feed the errors back when the cursor moves. If you added something that is erroneous it will not show up unless you save the file and move the cursor at least once.

How do I get the underlined errors? I get something different: This depends on how your current color theme is highlighting bad spelling. Khuno uses the same highlight for SpellBad, so however this is defined in your color theme is how it will look. If you are on a terminal and want to enforce underlining instead of something else, you can try this: hi SpellBad cterm=underline

Everything slows down when I move the cursor: If you are using terminal Vim and have the option to display the line where the cursor is (with :set cursorline) you will have performance problems. This is not the plugin per-se, but Vim will be slower to render. Two options to fix this: either disable it with :set nocursorline or use a GUI Vim (gVim, or MacVim for example).

About the name

Khuno is the name of an Inca God that ruled the cold weather and loved the snow. He would get very angry when someone messed with his snow. Now he rules another type of flakes, the Python ones.


Copyright (c) Alfredo Deza Distributed under the MIT license, see plugin for details.