Manipulation of the displayed text is done through highlighters, which
can be added or removed with the following commands:

add-highlighter <path>/<name> <type> <parameters> ...


remove-highlighter <path>/<name>

path is the name of a highlighter group, it is expressed as a /
separated path starting with a scope. Scopes are global, buffer,
window and shared

name is the name of the highlighter, if name is omitted in
add-highlighter (the path ends with a /), it will be auto-generated
from the remaining parameters.

Convenient highlighters

highlight matching char of the character under the selections’ cursor
using MatchingChar face

show-whitespaces [options]
display symbols on top of whitespaces to make them more explicit using
the Whitespace face, with the following options:

-lf <separator>
a one character long separator that will replace line feeds

-spc <separator>
a one character long separator that will replace spaces

-nbsp <separator>
a one character long separator that will replace non-breakable spaces

-tab <separator>
a one character long separator that will replace tabulations

-tabpad <separator>
a one character long separator that will be appended to tabulations to
honor the tabstop option

number-lines [options]
show line numbers using the LineNumbers, LineNumberCursor and
LineNumbersWrapped faces, with the following options:

show line numbers relative to the main cursor line

highlight the cursor line with a separate face

-separator <separator text>
specify a string to separate the line numbers column with the rest of
the buffer (default is |)

wrap [options]
soft wrap buffer text at window width, with the following options:

wrap at word boundaries instead of codepoint boundaries.

preserve line indent when wrapping.

-width <max_width>
wrap text at max_width if the window is wider.

-marker <marker_text>
prefix wrapped lines with marker_text; if -indent was given,
the marker_text is displayed into the indentation if possible.

General highlighters

fill <face>
fill using the given face, mostly useful with regions highlighters

column <number> <face>
highlight column number with face face

line <number> <face>
highlight line number with face face

regex <regex> <capture_id>:<face> …
highlight a regex, takes the regex as first parameter, followed by any
number of face parameters. This highlights C++ style comments in cyan,
with an eventual TODO: in yellow on red background:

add-highlighter window/ regex //\h*(TODO:)[^\n]* 0:cyan 1:yellow,red

capture_id can be either the capture number, or its name if a
named capture is used in the regex (See
<<regex#Groups, `:doc regex Groups`>>)

dynregex <expression> <capture_id>:<face> …
similar to regex, but expand (like a command parameter would) the given
expression before building a regex from the result. This highlights all
the current search matches in italic:

add-highlighter window/ dynregex '%reg{/}' 0:+i

Specs highlighters

The following highlighters are useful to add indicators like lint
warnings, git blame output or spelling typos. See
:doc options types for the format of line-specs
and range-specs.

flag-lines <face> <option_name>
add columns in front of the buffer, and display the flags specified in
line-specs option, using <face>. In this example two words will
be added in the gutter: a blue Foo at line 1 and a bold red/yellow Bar
on line 3:

declare-option line-specs my_flags
set-option window my_flags %val{timestamp} '1|Foo' '3|{red,yellow+b}Bar'
add-highlighter window/ flag-lines blue my_flags

ranges <option_name>
use the data in the range-specs option of the given name to highlight
the buffer. The string part of each tuple of the range-specs is
interpreted as a face to apply to the range. In this example the 3
first chars of the buffer will be colored in red:

declare-option range-specs my_range
set-option window my_range %val{timestamp} '1.1,1.3|red'
add-highlighter window/ ranges my_range

replace-ranges <option_name>
use the data in the range-specs option of the given name to highlight
the buffer. The string part of each tuple of the range-specs is
interpreted as a display line to display in place of the range.
Here, the 3 first chars of the buffer will be replaced by the word

declare-option range-specs my_range
set-option window my_range %val{timestamp} '1.1,1.3|red'
add-highlighter window/ replace-ranges my_range

Highlighting Groups

The group highlighter is a container for other highlighters. A
subgroup can be added to an existing group or scope using:

add-highlighter <path>/<name> group

Other highlighters can then be added to that group

add-highlighter <path>/<name> <type> <params>...

In order to specify which kinds of highlighters can be added to a given
group, the -passes flag set can be passed along with the group name.
Possible values for this option can be one or several (separated with a
pipe sign) of colorize, move or wrap (default:

add-highlighter window/<name> group -passes colorize|move|wrap

Regions highlighters

A special highlighter provides a way to segment the buffer into regions,
which are to be highlighted differently.

add-highlighter <path>/<name> regions

Individual region definitions can then be added to that highlighter

add-highlighter <path>/<name>/<region_name> region \
    [-match-capture] [-recurse <recurse>]          \
    <opening> <closing> <type> <params>...

regex that defines the region start text

regex that defines the region end text

regex that defines the text that matches recursively an end token into
the region, every match of recurse will consume a following match of
end, preventing it from closing the region.

type and params
An highlighter type, and associated params, as they would be passed to
add-highlighter if they were not applied as a region.

If the -match-capture switch is passed, then region closing and
recurse matches are considered valid for a given region opening match
only if they matched the same content for the capture 1.

The recurse option is useful for regions that can be nested, for
example the following contruct:

%sh{ ... }

accepts nested braces scopes ({ … }) so the following string is valid:

%sh{ ... { ... } ... }

This region can be defined with:

shell_expand -recurse \{ %sh\{ \}

Regions are matched using the left-most rule: the left-most region
opening starts a new region. When a region closes, the closest next
opening start another region.

That matches the rule governing most programming language parsing.

A default region, that will apply its given highlighter for segments of
the buffer that are not in any defined region, can be added with the
default-region highlighter type.

add-highlighter <path>/<name>/<region_name> default-region <type> <params>...

Most programming languages can then be properly highlighted using a
region highlighter as root:

add-highlighter <path>/<lang> regions
add-highlighter <path>/<lang>/string '"' '"' fill string
add-highlighter <path>/<lang>/comment '//' '$' fill comment
add-highlighter <path>/<lang>/code default-region group
add-highlighter <path>/<lang>/code/variable regex ...
add-highlighter <path>/<lang>/code/function regex ...

Shared Highlighters

Highlighters are often defined for a specific filetype, and it makes
then sense to share the highlighters between all the windows on the same

Highlighters can be put in the shared scope in order to make them

add-highlighter shared/<name> ...

The common case would be to create a named shared group, or regions and
then fill it with highlighters:

add-highlighter shared/ group <name>
add-highlighter shared/<name> regex ...

It can then be referenced in a window using the ref highlighter.

add-highlighter window/ ref <name>

The ref can reference any named highlighter in the shared scope.

One thing that isn’t clear here is how to nest regions. Adding another group to a group that has regions declared doesn’t seem to be allowed, but that isn’t obvious from this man page.

By staring at a bunch of the built in language highlighters, I was able to determine that at least one way is to create a group, add regexes to it, then create a new, unrelated group and some regions which then ref the first group. For example, in many templating languages (twig, mustache, etc), there are two kinds of tag regions, one for logical operations, the other for outputting variables. If you want to highlight a strings region within either of those regions, you need to define the two tag types as refs to the language grammar that includes string regions. This seems to be the resolution to the problem I stated here:

I’m sure there’s more tricks to be learned here. Looking at the JavaScript language kak script is bewildering. It uses recursion in a way I don’t have time to reverse engineer.


Sorry if I’m being dense, but I think it would help to have a few simple, practical examples.

For example, let’s say I want to highlight a specific word from a file. For example, the word TODO in a markdown file, or a nickname in a chat log …

EDIT: shit sorry I skipped the part where there is an example like that. Sorry for the noise!

1 Like

It’s not being dense, it’s being pedagogical. Not all of us are that tech savvy, and examples clarifies many things that words take longer.

Please, add examples in every concept.