Conditionals

Yolk allows you to conditionally include parts of your configuration based on the state of your system. It achieves this by commenting or un-commenting blocks of your file.

Conditionals use special template tags that start with the keyword if, which instructs Yolk to treat the following expression as a conditional, rather than a regular template tag function.

Multiline conditionals

The most common form of conditional block is using the multiline template tag syntax. Let's type out a simple example:

# {% if SYSTEM.hostname == "epic-desktop" %}
displays = ["DP-1", "DP-2"]
# {% if SYSTEM.hostname == "business-desktop" %}
displays = ["HDMI-1", "HDMI-2"]
# {% else %}
displays = ["eDP-1"]
# {% end %}

Now, this is of course not a valid configuration just yet, as we're setting the displays variable thrice.

However, once you run yolk sync, yolk will evaluate the condition and comment out the blocks that don't apply. For example, on your laptop, this config might be turned into:

# {% if SYSTEM.hostname == "epic-desktop" %}
#<yolk> displays = ["DP-1", "DP-2"]
# {% if SYSTEM.hostname == "business-desktop" %}
#<yolk> displays = ["HDMI-1", "HDMI-2"]
# {% else %}
displays = ["eDP-1"]
# {% end %}

Note thta yolk added a special <yolk> prefix to the comments. Yolk conditionals will only ever add or remove comments with this prefix, which means that you can still have regular comments in those conditional blocks.

Inline and Next-line conditionals

A more simplified version of this is also supported in inline and next-line tags:

enable_variable_refreshrate // {< if data.is_desktop() >}

// {# if data.enable_xwayland #}
spawn-at-startup "xwayland-satellite"