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Named colours as data — CSS3, Crayola, X11 and more, each name paired with its RGB triple, plus a substring search and a nearest-match by distance.

Version

2.0.0 zef:thundergnat

Depends

nothing outside the core

License

BSD-2-Clause

Its own test suite

3 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 Color::Names

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

What it is for #

"Rebecca purple" is a colour a person can say and a computer cannot, until something maps the name onto 102, 51, 153. That mapping is pure reference data, it is bigger than you want to paste into a program, and there is more than one of it — CSS3's list, Crayola's crayon names, the X11 set that ships with every window system, and several others besides.

This distribution is those lists, as hashes. Nothing is computed at load time beyond building the table you ask for, and the sets are separate units so a program pulling in CSS3 does not pay for Crayola.

Looking a colour up, and finding one #

Each palette is its own unit, imported with :colors, and Color::Names.color-data assembles the hash — the keys carry the palette name as a suffix, so several sets can be merged without collisions:

use Color::Names;
use Color::Names::CSS3 :colors;

my %css = Color::Names.color-data('CSS3');
say %css.elems, ' CSS3 colours';

my %c = %css<rebeccapurple-CSS3>;
say %c<name>, ' = ', %c<rgb>.join(', ');

for find-color(%css, 'slate').sort(*.key) -> $p {
    say $p.key, ' — ', $p.value<name>;
}

141 CSS3 colours
Rebecca Purple = 102, 51, 153
darkslateblue-CSS3 — Dark Slate Blue
darkslategray-CSS3 — Dark Slate Gray
lightslategray-CSS3 — Light Slate Gray
mediumslateblue-CSS3 — Medium Slate Blue
slateblue-CSS3 — Slate Blue
slategray-CSS3 — Slate Gray

Every entry is a hash of name — the human spelling, capitalised — and rgb, an array of three integers. find-color is a substring search over the keys returning a Seq of Pairs, which is the right shape for offering a user the six things they might have meant. Its :ex adverb narrows it to an exact match. nearest answers the other question: given an arbitrary RGB triple, which named colour is closest.

The one thing to know #

The key is not the name. %css<rebeccapurple-CSS3> works and %css<rebeccapurple> gives an undefined value, because every key has its palette appended — and that is a deliberate feature rather than an inconvenience. It is what lets you merge CSS3 and Crayola into one table and still tell a CSS "Green" from a Crayola "Green", which are not the same colour.

The consequence is that a name arriving from outside your program — typed by a user, read from a config file — is never a key on its own. Either append the palette you decided on, or put the name through find-color with :ex and handle the empty result. Reaching straight into the hash with user input gets you Any and, one line later, a failure somewhere that has nothing to do with the lookup.