Distribution · terminal

Terminal::ANSI

Works

The ANSI escape sequences with names — bold, colour, cursor movement, alternate screen — offered twice over: as subs that write to the terminal, and as an object whose methods hand you the string instead.

Version: 0.0.25 cpan:bduggan
Depends: OO::Monitors
License: MIT
Its own test suite: 8 files, green
Checked: 2026-09-14 against Raku++ 3.28.0 and Rakudo 2026.08
Where it lives: raku.land · source

Install it #

$ rakupp install Terminal::ANSI

zef install Terminal::ANSI writes the same store; either installer leaves the module usable by both engines.

What it is for #

A terminal program that wants colour, or wants to put a character at row 12 column 40, talks to the terminal in escape sequences: ESC [ 1 m for bold, ESC [ 12 ; 40 H to move. They are short enough to inline and just cryptic enough that a typo shows up as garbage on screen rather than as an error.

This distribution names them. Fifty-one exported subs cover attributes (bold, italic, underline, strike, blink), colour by palette index or by RGB triple, the cursor (move-to, save-cursor, cursor-up), the screen (clear-screen, save-screen, erase-to-end-of-line), and scroll regions.

Two units, and the difference matters #

Terminal::ANSI exports subs that write the escape to standard output and return True. Terminal::ANSI::OO exports a single term t whose methods return the escape as a string, to be concatenated into something you print later:

File

use Terminal::ANSI::OO;

say t.bold.raku;
say t.red.raku;
say t.text-reset.raku;

say (t.bold ~ 'shouted' ~ t.text-reset).raku;

Output

"\x[1B][1m"
"\x[1B][38;5;1m"
"\x[1B][0m"
"\x[1B][1mshouted\x[1B][0m"

The escapes are shown through .raku here so they are legible on a web page; printed to a terminal they are invisible and the word comes out bold and red. \x[1B] is ESC, and [0m is the reset that every sequence you open should be closed with — leave it out and the next thing written, including your shell prompt after the program exits, inherits the attribute.

For whole-screen work the procedural side reads better, since you want the effect and not the string: print-at($row, $col, $text), save-screen and restore-screen around a full-screen view, cursor-off while you draw.

The one thing to know #

bold() and t.bold look interchangeable and are not. The bare sub prints immediately and evaluates to True, so building a string out of the procedural subs gives you the escapes on screen at the wrong moment and the word True where the colour should be:

# writes the escape NOW, then interpolates "True"
my $label = bold() ~ 'shouted' ~ text-reset();

Reach for Terminal::ANSI::OO whenever the sequence is going into a variable, a log line, a sprintf, or anything other than the terminal right now. The procedural subs are for when printing is the point.

Worth knowing too: the module can be switched off wholesale. disable-output makes the procedural subs no-ops, which is the hook for a --no-colour flag or for detecting that output is a pipe rather than a terminal — one call at start-up instead of a conditional at every call site.