A.2 library(ansi_term): Print decorated text to ANSI consoles

See also

http://en.wikipedia.org/wiki/ANSI_escape_code

This library allows for exploiting the color and attribute facilities of most modern terminals using ANSI escape sequences. This library provides the following:

• ansi_format/3 allows writing messages to the terminal with ansi attributes.
• It defines the hook prolog:message_line_element/2, which provides ansi attributes for print_message/2.

[det]ansi_format(+Attributes, +Format, +Args)

Format text with ANSI attributes. This predicate behaves as format/2 using Format and Args, but if the current_output is a terminal, it adds ANSI escape sequences according to Attributes. For example, to print a text in bold cyan, do

?- ansi_format([bold,fg(cyan)], 'Hello ~w', [world]).

Attributes is either a single attribute or a list thereof. The attribute names are derived from the ANSI specification. See the source for sgr_code/2 for details. Some commonly used attributes are:

• bold
• underline
• fg(Color), bg(Color), hfg(Color), hbg(Color)

Defined color constants are below. default can be used to access the default color of the terminal.

• black, red, green, yellow, blue, magenta, cyan, white

ANSI sequences are sent if and only if

• The current_output has the property tty(true) (see stream_property/2).
• The Prolog flag color_term is true.

[semidet,multifile]prolog:message_line_element(+Stream, +Term)

Hook implementation that deals with ansi(+Attr, +Fmt, +Args) in message specifications.