By default, SWI-Prolog will use colored output on the commandline based on library(ansi_term) if the current_output stream is connected to a terminal. This is detected by the tty property of streams (see stream_property/2). Coloring can be controlled in two ways

• It can be disabled using this in your personal initialization file (see below).

  :- set_prolog_flag(color_term, false).

• Colors can be changed by message type (see print_message/2) using the hook message_property/2.

Dark mode

Color themes are defined in the theme subdirectory of the library. These control both color handling in the console and the xpce based IDE tools such as PceEmacs. The system ships with two themes:

• dark
  Self explanatory
• auto
  Try to fetch the colors from the attached console and select dark if this seems more applicable. Note that not all console applications are capable of exposing their color scheme. See ansi_get_color/2.

New themes can be added, for example to your personal library. The easiest way to define a new theme is by cloning the dark theme.

See also

- PlInitialisation.md for editing your personal init file.